What's In My Water · The State of New Zealand's Tap Water, 2026 · No Brainer Water Co. · https://nobrainerwater.co.nz/water/state-of-nz-tap-water.html · printed from the edition of 2026-09-15
What's In My Water · First edition · 140 supplies · 18 councils and water companies
The State of New Zealand's Tap Water, 2026
This is the first edition of an annual report on what is in New Zealand's tap water. It is built from 18 councils' and council-owned water companies' own lab results, released under the Local Government Official Information and Meetings Act, plus the national regulator's extract released under the Official Information Act. Every number traces to a release. Every supply links to its district page.
140
supplies covered
From 18 council and water-company releases, 24,511 chlorine samples and 11,770 zone E. coli samples.
86%
above an international health goal
121 of 140 carry at least one reading above the EWG health guideline for trihalomethanes, haloacetic acids or lead.
99%
never tested for PFAS
139 of 140. The one that was tested, Hamilton, found none.
37 / 51 / 52
fluoridated / not / not stated
37 supplies fluoridated, 51 not, and 52 where the release does not say.
97%
zero E. coli detections
123 of the 127 supplies with zone E. coli results had no detection all period. 13 releases carry no zone E. coli result.
19
supplies with nothing above a health goal
No by-product or lead reading above an EWG guideline in the release. The clean list is table 6.
The honest frameEvery supply on this page passes New Zealand's legal limits. The exceptions, each from the council's own lab, are Duvauchelle (haloacetic acids (total) over the New Zealand standard), Little River (haloacetic acids (total) over the New Zealand standard), Waihemo, Goodwood Rural (lead over the New Zealand standard, with the council's resample recorded beside it in table 3), Waihemo, Palmerston Town (lead over the New Zealand standard, with the council's resample recorded beside it in table 3), Lower Waitaki (lead over the New Zealand standard, with the council's resample recorded beside it in table 3) and Puriri (lead and E. coli over the New Zealand standard, an untreated supply on the council's own description). The tables show where each supply sits against the international health guidelines, which sit far lower than the legal limits, and what has never been tested at all. The shape of every line is the same: inside New Zealand's legal limit, and N times the international health guideline.
League table 1
Trihalomethanes
Trihalomethanes form when chlorine meets natural organic matter in the water. 98 of the 140 supplies returned a measured reading, ranked here by how many times the highest reading sits above the EWG health guideline of 0.00015 mg/L. New Zealand sets no single total-THM cap; the rule is that each species' share of its own limit must add to less than 1, and the tightest single limit is 0.06 mg/L. The highest reading, 0.1399 mg/L at Foxton, is 932x the guideline.
- 1 per-sample sum of quantified THM species (chloroform, bromodichloromethane, dibromochloromethane quantified in every sample; bromoform quantified in some, <0.0005 in the rest), agreeing with the lab's printed 'Sum of Trihalomethanes' to its 3-dp rounding on every sample; nz_mav_ratio_max is recomputed from the species against the NZ MAVs (chloroform 0.4, BDCM 0.06, DBCM 0.15, bromoform 0.1 mg/L) - the lab's printed ratio reproduces it on every sample except the 1 Sep 2025 round, where the five printed ratios (0.163-0.183) do not follow from the species and are not used
- 2 per-date sum of the four quantified THM species (chloroform, bromodichloromethane, dibromochloromethane, bromoform) from the council's quarterly D3.22 sampling; a species reported below detection is not summed; the ratio is the sum of each species over its own NZ MAV
- 3 per-date sum of quantified THM species (no lab total printed in the release); NZ MAV ratio sum computed from the species
- 4 per-date sum of quantified THM species (chloroform, bromodichloromethane, dibromochloromethane, bromoform); reproduces the lab's printed 'Trihalomethanes - Total' within rounding on every date it is printed. nz_mav_ratio_max is the NZ MAV sum ratio per date - the lab's printed 'THM Ratio' where it printed one (1 of 1 dates; the species-computed ratio reproduces it within 0.016 every time), the species-computed ratio otherwise
- 5 per-date sum of quantified THM species (chloroform, bromodichloromethane, dibromochloromethane, bromoform); reproduces the lab's printed 'Trihalomethanes - Total' within rounding on every date it is printed. nz_mav_ratio_max is the NZ MAV sum ratio per date - the lab's printed 'THM Ratio' where it printed one (2 of 5 dates; the species-computed ratio reproduces it within 0.016 every time), the species-computed ratio otherwise
- 6 per-tap sum of quantified THM species on 22 Jul 2026 (the release's one by-product round); the lab prints no THM total, only its 'Total THM MAV Ratio', which the species-computed ratio reproduces (a below-detection species counted at zero here, sometimes at its limit by the lab)
- 7 per-date sum of quantified THM species (chloroform, bromodichloromethane, dibromochloromethane, bromoform); reproduces the lab's printed 'Trihalomethanes - Total' within rounding on every date it is printed. nz_mav_ratio_max is the NZ MAV sum ratio per date - the lab's printed 'THM Ratio' where it printed one (0 of 1 dates; the species-computed ratio reproduces it within 0.016 every time), the species-computed ratio otherwise
- 8 per-date sum of quantified THM species (chloroform, bromodichloromethane, dibromochloromethane, bromoform); reproduces the lab's printed 'Trihalomethanes - Total' within rounding on every date it is printed. nz_mav_ratio_max is the NZ MAV sum ratio per date - the lab's printed 'THM Ratio' where it printed one (1 of 1 dates; the species-computed ratio reproduces it within 0.016 every time), the species-computed ratio otherwise. 2026-01-15: no dibromochloromethane species column in the export (only its MAV ratio 0.05, implying about 0.0075 mg/L); the lab's printed total 0.017 mg/L is used for that date
- 9 per-date sum of quantified THM species (chloroform, bromodichloromethane, dibromochloromethane quantified; bromoform <0.0005 in every round); nz_mav_ratio_max is the lab's own printed Total THM MAV Ratio, which the species-computed ratio reproduces within 0.0035 in every round (the lab counts a below-detection species at its detection limit, so its figure is the higher of the two)
- 10 2025-10-09: export lacks ['bdcm'] column(s); lab sum-of-ratios 0.091 implies a higher true total than the 2-species sum
Each reading is the highest total in the council's release for that supply over its stated period. "Inside" means the release records no exceedance of a New Zealand maximum acceptable value; where the lab printed a compliance ratio it is shown. Supplies with no measured THM are not listed: 42 supplies had THMs below detection or no result.
League table 2
Haloacetic acids
Haloacetic acids are the other main family of chlorination by-products. 66 supplies returned a measured total, ranked against the EWG health guideline of 0.0001 mg/L. New Zealand limits three species individually; the tightest is dichloroacetic acid at 0.05 mg/L. 2 of these supplies went over the New Zealand standard itself on the lab's own compliance ratio.
- 1 per-sample sum of quantified HAA species (dichloroacetic and trichloroacetic acid are the ones that quantify, plus one bromochloroacetic acid result at its 0.005 detection limit; trichloroacetic acid's detection limit is 0.05 mg/L so a 0.06 result sits just above it); samples with every species below detection contribute no value; no lab-printed HAA sum in the export
- 2 per-date sum of quantified dichloroacetic acid (NZ MAV 0.05) and trichloroacetic acid (NZ MAV 0.2), the ONLY two haloacetic acids in the council's D3.22 export - monthly, not an HAA5; a species below detection (<0.004) is not summed, and a round with both below detection contributes no sum (counted in rounds_both_below_detection). species_max gives each acid's own peak so it can be read against its own limit; nz_mav_ratio_computed_max is DCAA/0.05 + TCAA/0.2. Neither acid exceeds its own MAV in any round
- 3 per-date sum of every quantified haloacetic acid species the lab reports (bromoacetic, bromochloroacetic, chloroacetic, dibromoacetic, dichloroacetic, trichloroacetic); nz_mav_ratio_max is the lab's printed 'HAA Sum Ratio', reproduced from dichloroacetic/0.05 + trichloroacetic/0.2 + chloroacetic/0.02 on every date. 2026-01-15: no dichloroacetic acid column in the export for this sample; the lab's printed HAA Sum Ratio 0.19 less the trichloroacetic acid share implies about 0.0087 mg/L dichloroacetic acid, which is folded into the sum and flagged as derived
- 4 per-date sum of every quantified haloacetic acid species the lab reports (bromoacetic, bromochloroacetic, chloroacetic, dibromoacetic, dichloroacetic, trichloroacetic); nz_mav_ratio_max is the lab's printed 'HAA Sum Ratio', reproduced from dichloroacetic/0.05 + trichloroacetic/0.2 + chloroacetic/0.02 on every date
- 5 sum of quantified HAA5 species (MCAA, DCAA, TCAA, MBAA, DBAA); bromochloroacetic acid excluded
- 6 dichloroacetic acid is the only HAA species the lab ever quantified; chloroacetic, bromochloroacetic, dibromoacetic and monobromoacetic acid read <0.005 mg/L and trichloroacetic acid <0.05 in every round, so a total is the dichloroacetic value and the not-detected ceiling is the 0.005 limit shared by five of the six species (trichloroacetic acid's coarser limit is stated, not folded in)
- 7 sum of quantified species of the two HAAs in the release (dichloroacetic, trichloroacetic); trichloroacetic acid reported <0.05 in every sample, so the figure is dichloroacetic acid alone
Totals are the lab's own printed total where the release prints one, otherwise the sum of the quantified species, as each district page states. 74 supplies had haloacetic acids below detection or no result.
League table 3
Lead detections against the zero goal
Lead does not come from the treatment plant. It is picked up on the way to the tap from old pipes, solder and brass fittings. The US EPA health goal is zero and the World Health Organization says there is no known safe level. New Zealand's legal limit is 0.01 mg/L. Lead was detected in 90 of the 140 supplies; the highest reading, 0.234 mg/L at Waihemo, Palmerston Town, is 2340% of the legal limit and 1170x the EWG guideline of 0.0002 mg/L - the council's own follow-up sample sits beside it in the table. 50 supplies tested for lead and found none.
76 of the 90 detections sit above the EWG guideline; the rest were detected at or below it. Readings are the highest of the samples in the release, all taken in the network, not at the plant.
Table 4
Fluoride
Fluoride is added deliberately. Of the 140 supplies, 37 are fluoridated, 51 are not, and for 52 the release neither states it nor holds a fluoride result. Where a level was released it is shown; the highest single reading in the library is 1.41 mg/L at Palmerston North against a legal limit of 1.5 mg/L. Fluoride never counts toward the health-goal figure on this page.
| Supply | Council | Status | Measured level, where the release holds one |
|---|---|---|---|
| Hamilton | Hamilton City Council | Fluoridated | median 0.77 mg/L, max 0.82, 6 samples |
| Levin | Horowhenua District Council | Fluoridated | median 0.81 mg/L, max 1.24, 9537 samples |
| Bluff | Invercargill City Council | Fluoridated | median 0.72 mg/L, max 0.85, 14 samples |
| Invercargill | Invercargill City Council | Fluoridated | median 0.72 mg/L, max 0.85, 14 samples |
| Waikanae/Paraparaumu/Raumati | Kapiti Coast District Council | Fluoridated | added - level not in the release |
| Masterton | Masterton District Council | Fluoridated | median 0.87 mg/L, max 0.97, 92 samples |
| Bell Block | New Plymouth District Council | Fluoridated | median 0.65 mg/L, max 0.72, 24 samples |
| New Plymouth | New Plymouth District Council | Fluoridated | median 0.65 mg/L, max 0.72, 24 samples |
| Tikorangi/Urenui | New Plymouth District Council | Fluoridated | median 0.65 mg/L, max 0.72, 24 samples |
| Waitara | New Plymouth District Council | Fluoridated | median 0.65 mg/L, max 0.72, 24 samples |
| Ashhurst | Palmerston North City Council | Fluoridated | median 0.82 mg/L, max 1.09, 54 samples |
| Bunnythorpe | Palmerston North City Council | Fluoridated | median 0.76 mg/L, max 0.92, 53 samples |
| Longburn | Palmerston North City Council | Fluoridated | median 0.75 mg/L, max 0.85, 46 samples |
| Palmerston North | Palmerston North City Council | Fluoridated | median 0.78 mg/L, max 1.41, 268 samples |
| Central (Rotorua city) | Rotorua Lakes Council | Fluoridated | median 0.60 mg/L, max 0.85, 77 samples |
| Eastern (Rotorua city) | Rotorua Lakes Council | Fluoridated | median 0.53 mg/L, max 0.79, 66 samples |
| Okareka | Rotorua Lakes Council | Fluoridated | median 0.53 mg/L, max 0.73, 73 samples |
| Tauranga | Tauranga City Council | Fluoridated | median 0.78 mg/L, max 0.80, 3 samples |
| Thames | Thames-Coromandel District Council | Fluoridated | median 0.03 mg/L, max 0.52, 9 samples |
| Huntly | Waikato District Council | Fluoridated | median 0.85 mg/L, max 0.85, 1 sample |
| Ngaaruawaahia | Waikato District Council | Fluoridated | median 0.72 mg/L, max 0.72, 1 sample |
| Northwestern District | Waikato District Council | Fluoridated | added - level not in the release |
| Pookeno | Waikato District Council | Fluoridated | added - level not in the release |
| Southern District | Waikato District Council | Fluoridated | added - level not in the release |
| Te Kauwhata | Waikato District Council | Fluoridated | median 0.67 mg/L, max 0.67, 1 sample |
| Tuakau South | Waikato District Council | Fluoridated | added - level not in the release |
| Western District | Waikato District Council | Fluoridated | added - level not in the release |
| Oamaru, Ardgowan | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Oamaru, Central | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Oamaru, Hampden | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Oamaru, Herbert | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Oamaru, Kakanui | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Oamaru, Moeraki | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Oamaru, North End | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Oamaru, Old Mill Road (Reservoir Road) | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Oamaru, South Hill | Waitaki District Council | Fluoridated | median 0.72 mg/L, max 0.79, 10 samples |
| Oamaru, Weston - Enfield | Waitaki District Council | Fluoridated | median 0.74 mg/L, max 0.78, 10 samples |
| Akaroa-Takamatua | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Birdlings Flat | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Brooklands/Kainga | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Central Christchurch | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Duvauchelle | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Ferrymead | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Little River | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Northwest Christchurch | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Parklands | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Pigeon Bay | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Rawhiti | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Riccarton | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Wainui | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| West Christchurch | Christchurch City Council | Not fluoridated | no fluoridation step in the release |
| Foxton | Horowhenua District Council | Not fluoridated | no fluoridation step in the release |
| Foxton Beach | Horowhenua District Council | Not fluoridated | no fluoridation step in the release |
| Shannon | Horowhenua District Council | Not fluoridated | no fluoridation step in the release |
| Tokomaru | Horowhenua District Council | Not fluoridated | no fluoridation step in the release |
| Hautere | Kapiti Coast District Council | Not fluoridated | no fluoridation step in the release |
| Otaki | Kapiti Coast District Council | Not fluoridated | no fluoridation step in the release |
| Paekakariki | Kapiti Coast District Council | Not fluoridated | no fluoridation step in the release |
| Inglewood | New Plymouth District Council | Not fluoridated | no fluoridation step in the release |
| Oakura | New Plymouth District Council | Not fluoridated | no fluoridation step in the release |
| Okato | New Plymouth District Council | Not fluoridated | no fluoridation step in the release |
| Hamurana | Rotorua Lakes Council | Not fluoridated | no fluoridation step in the release |
| Kaharoa | Rotorua Lakes Council | Not fluoridated | no fluoridation step in the release |
| Mamaku | Rotorua Lakes Council | Not fluoridated | no fluoridation step in the release |
| Ngongotaha | Rotorua Lakes Council | Not fluoridated | no fluoridation step in the release |
| Reporoa | Rotorua Lakes Council | Not fluoridated | no fluoridation step in the release |
| Rotoiti | Rotorua Lakes Council | Not fluoridated | no fluoridation step in the release |
| Rotoma | Rotorua Lakes Council | Not fluoridated | no fluoridation step in the release |
| Coromandel | Thames-Coromandel District Council | Not fluoridated | no fluoridation step in the release |
| Hahei | Thames-Coromandel District Council | Not fluoridated | no fluoridation step in the release |
| Matarangi | Thames-Coromandel District Council | Not fluoridated | no fluoridation step in the release |
| Onemana | Thames-Coromandel District Council | Not fluoridated | no fluoridation step in the release |
| Pauanui | Thames-Coromandel District Council | Not fluoridated | no fluoridation step in the release |
| Puriri | Thames-Coromandel District Council | Not fluoridated | no fluoridation step in the release |
| Tairua | Thames-Coromandel District Council | Not fluoridated | no fluoridation step in the release |
| Whangamata | Thames-Coromandel District Council | Not fluoridated | no fluoridation step in the release |
| Onewhero | Waikato District Council | Not fluoridated | no fluoridation step in the release |
| Port Waikato | Waikato District Council | Not fluoridated | no fluoridation step in the release |
| Raglan | Waikato District Council | Not fluoridated | no fluoridation step in the release |
| Te Aakau | Waikato District Council | Not fluoridated | no fluoridation step in the release |
| Athol | Waikato Waters | Not fluoridated | measured at natural background: 0.064, 0.052, 0.06 mg/L |
| Cambridge | Waikato Waters | Not fluoridated | measured at natural background: 0.111, 0.12 mg/L |
| Karapiro Village | Waikato Waters | Not fluoridated | measured at natural background: 0.11, 0.129 mg/L |
| Kihikihi | Waikato Waters | Not fluoridated | measured at natural background: 0.07, 0.064 mg/L |
| Pirongia | Waikato Waters | Not fluoridated | measured at natural background: <0.05, <0.05 mg/L |
| Pukerimu Rural | Waikato Waters | Not fluoridated | measured at natural background: 0.13, 0.15 mg/L |
| Putaruru | Waikato Waters | Not fluoridated | measured at natural background: <0.05, <0.05, 0.05 mg/L |
| Te Awamutu | Waikato Waters | Not fluoridated | measured at natural background: 0.13, 0.1 mg/L |
| Kaimanawa | Hauraki District Council | Not stated in the release | no fluoride result or statement in the release |
| Karangahake | Hauraki District Council | Not stated in the release | no fluoride result or statement in the release |
| Kerepehi/Waitakaruru | Hauraki District Council | Not stated in the release | no fluoride result or statement in the release |
| Paeroa | Hauraki District Council | Not stated in the release | no fluoride result or statement in the release |
| Waihi | Hauraki District Council | Not stated in the release | no fluoride result or statement in the release |
| Waikino | Hauraki District Council | Not stated in the release | no fluoride result or statement in the release |
| Baylys Beach | Kaipara District Council | Not stated in the release | no fluoride result or statement in the release |
| Dargaville | Kaipara District Council | Not stated in the release | no fluoride result or statement in the release |
| Maungaturoto | Kaipara District Council | Not stated in the release | no fluoride result or statement in the release |
| Maungaturoto Railway Village | Kaipara District Council | Not stated in the release | no fluoride result or statement in the release |
| Ruawai | Kaipara District Council | Not stated in the release | no fluoride result or statement in the release |
| Tinui | Masterton District Council | Not stated in the release | no fluoride result or statement in the release |
| Hinuera | Matamata-Piako District Council | Not stated in the release | no fluoride result or statement in the release |
| Matamata | Matamata-Piako District Council | Not stated in the release | no fluoride result or statement in the release |
| Morrinsville | Matamata-Piako District Council | Not stated in the release | no fluoride result or statement in the release |
| Tahuna | Matamata-Piako District Council | Not stated in the release | no fluoride result or statement in the release |
| Te Aroha | Matamata-Piako District Council | Not stated in the release | no fluoride result or statement in the release |
| Te Poi | Matamata-Piako District Council | Not stated in the release | no fluoride result or statement in the release |
| Waharoa | Matamata-Piako District Council | Not stated in the release | no fluoride result or statement in the release |
| Geraldine | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Geraldine Downs | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Geraldine Flat | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Gleniti | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Hadlow | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Orari | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Pareora | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Peel Forest | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Pleasant Point | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Rangitata Huts | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Seadown | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| St Andrews | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Sutherlands/Taiko | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Te Moana | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Temuka | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Timaru | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Upper Pareora | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Waimate Rural | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Waitohi/Totara Valley | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Winchester | Timaru District Council | Not stated in the release | no fluoride result or statement in the release |
| Whangamarino | Waikato District Council | Not stated in the release | no fluoride result or statement in the release |
| Benneydale | Waikato Waters | Not stated in the release | no fluoride result or statement in the release |
| Piopio | Waikato Waters | Not stated in the release | no fluoride result or statement in the release |
| Awamoko | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Kauru Hill | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Lower Waitaki | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Omarama Town | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Otematata (Hydro Village) | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Tokarahi/Livingstone | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Waihemo, Dunback Rural | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Waihemo, Goodwood Rural | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Waihemo, Palmerston Town | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
| Windsor | Waitaki District Council | Not stated in the release | no fluoride result or statement in the release |
- Bell Block, New Plymouth, Tikorangi/Urenui and Waitara: treated water at the New Plymouth WTP tap (council LabOnline, fluoride by IC), 2025-08-04 to 2026-07-27 - plant water feeding this zone, not a reticulation sample; the two July 2026 results (0.05, 0.07) sit at natural background
- Levin: Levin WTP online fluoride analyser on the treated water leaving the plant for town ('Levin Fluoride to Town'), hourly, 2025-08-01 to 2026-09-02 - 9,537 readings, plant outlet not a reticulation tap; 8,369 readings sit in the 0.7-1.0 mg/L target band, 1,139 below it (two dosing dips: 27-29 Aug 2025 down to 0.092 and 4-7 Jul 2026 down to 0.112) and 29 above it, peak 1.242 against the 1.5 mg/L MAV; the requested 12 months (14 Aug 2025 to 13 Aug 2026) hold 8,759 readings, median 0.81, max 1.242; one negative analyser reading excluded
- Masterton: Upper Plain Reservoir, a service reservoir on the Masterton urban supply, sampled by the council's lab roughly twice a week, 2025-06-03 to 2026-08-24 - reservoir water feeding the network, not a reticulation tap; every result 0.74-0.97 mg/L (a 0.30 first entry on 9 Feb 2026 was re-entered by the council as 0.82 and is excluded)
- Oamaru, Ardgowan, Oamaru, Central, Oamaru, Hampden, Oamaru, Herbert, Oamaru, Kakanui, Oamaru, Moeraki, Oamaru, North End, Oamaru, Old Mill Road (Reservoir Road) and Oamaru, Weston - Enfield: treated water at the Oamaru WTP fluoride analyser tap (lab check samples, monthly, 2025-08-05 to 2026-05-19) - plant water feeding this zone, not a reticulation tap; the only reticulation fluoride in the release is at Oamaru South Hill (0.56-0.79 mg/L)
- Oamaru, South Hill: reticulation fluoride at the Oamaru South Hill tap, the lab's monthly check sample paired with the plant analyser sample, 2025-08-05 to 2026-05-19 - the only reticulation fluoride in the release
- Thames: nine lab fluoride results at Thames zone sampling points, Veolia era only (2025-07-03 to 2026-03-26); the Watercare-era export has no fluoride column. One result of 0.52 mg/L (Kirikiri West Road, 3 Jul 2025), then 0.03-0.07 in five and below 0.02 in three - far under the 0.7-1.0 mg/L dosing target; fluoride_min is the lowest quantified value
Table 5
The PFAS table
PFAS, the forever chemicals, are not part of routine council monitoring. Across the 18 releases, 139 of 140 supplies have no PFAS test at all. Hamilton is the one that was tested, and nothing was detected. The regulator's own zone-level extract holds no PFAS determinand either.
"Not tested in the release" means no PFAS, PFOA or PFOS determinand appears anywhere in what the council released for these supplies. New Zealand's standards carry limits for PFOA and for PFOS plus PFHxS combined; testing for them is not part of the routine zone monitoring these releases document.
Table 6
The clean list
19 of the 140 supplies carry no reading above an international health guideline in their release: by-products below detection or not present, and no lead detected. This is what the releases show, not a claim about what was never tested; none of these 19 has a PFAS test either.
| Supply | Council | By-products and lead in the release | E. coli detections | Chlorine |
|---|---|---|---|---|
| Birdlings Flat | Christchurch City Council | THMs: no reportable result in the release; HAAs: below detection in 4 samples (under 0.01); lead: not detected in 1 sample (under 0.001) | 0 in 12 | 0.54 mg/L median, 105 samples |
| Brooklands/Kainga | Christchurch City Council | THMs: below detection in 4 samples (under 0.02); HAAs: no reportable result in the release; lead: not detected in 2 samples (under 0.001) | 0 in 104 | 0.41 mg/L median, 209 samples |
| Central Christchurch | Christchurch City Council | THMs: below detection in 4 samples (under 0.02); HAAs: no reportable result in the release; lead: not detected in 2 samples (under 0.001) | 0 in 208 | 0.41 mg/L median, 367 samples |
| Ferrymead | Christchurch City Council | THMs: below detection in 16 samples (under 0.02); HAAs: no reportable result in the release; lead: not detected in 9 samples (under 0.001) | 0 in 469 | 0.42 mg/L median, 774 samples |
| Northwest Christchurch | Christchurch City Council | THMs: below detection in 4 samples (under 0.02); HAAs: no reportable result in the release; lead: not detected in 2 samples (under 0.001) | 0 in 156 | 0.39 mg/L median, 312 samples |
| Parklands | Christchurch City Council | THMs: below detection in 4 samples (under 0.02); HAAs: below detection in 4 samples (under 0.01); lead: not detected in 2 samples (under 0.001) | 0 in 104 | 0.33 mg/L median, 208 samples |
| Rawhiti | Christchurch City Council | THMs: below detection in 4 samples (under 0.02); HAAs: below detection in 4 samples (under 0.01); lead: not detected in 2 samples (under 0.001) | 0 in 104 | 0.35 mg/L median, 262 samples |
| Riccarton | Christchurch City Council | THMs: below detection in 4 samples (under 0.02); HAAs: below detection in 3 samples (under 0.01); lead: not detected in 2 samples (under 0.001) | 0 in 104 | 0.75 mg/L median, 208 samples |
| Wainui | Christchurch City Council | THMs: below detection in 4 samples (under 0.02); HAAs: below detection in 4 samples (under 0.01); lead: not detected in 1 sample (under 0.001) | 0 in 11 | 0.52 mg/L median, 69 samples |
| West Christchurch | Christchurch City Council | THMs: below detection in 4 samples (under 0.02); HAAs: no reportable result in the release; lead: not detected in 2 samples (under 0.001) | 0 in 174 | 0.41 mg/L median, 349 samples |
| Tinui | Masterton District Council | THMs: no result in the release; HAAs: no result in the release; lead: not detected in 1 sample (under 0.001) | 0 in 15 | 0.61 mg/L median, 14 samples |
| Ashhurst | Palmerston North City Council | THMs: no reportable result in the release; HAAs: below detection in 3 samples (under 0.01); lead: not detected in 3 samples (under 0.001) | 0 in 52 | 0.94 mg/L median, 158 samples |
| Hahei | Thames-Coromandel District Council | THMs: no result in the release; HAAs: no result in the release; lead: not detected in 1 sample (under 0.0001) | 0 in 23 | 1.12 mg/L median, 5 samples |
| Raglan | Waikato District Council | THMs: below detection in 1 sample (under 0.0004); HAAs: below detection in 1 sample (under 0.006); lead: not detected in 1 sample (under 0.0001) | 0 in 108 | 0.93 mg/L median, 163 samples |
| Awamoko | Waitaki District Council | THMs: no result in the release; HAAs: no result in the release; lead: not detected in 1 sample (under 0.001) | 0 in 13 | 0.83 mg/L median, 107 samples |
| Kauru Hill | Waitaki District Council | THMs: no result in the release; HAAs: no result in the release; lead: not detected in 1 sample (under 0.001) | 0 in 13 | 0.59 mg/L median, 103 samples |
| Omarama Town | Waitaki District Council | THMs: no result in the release; HAAs: no result in the release; lead: not detected in 1 sample (under 0.001) | 0 in 23 | 0.67 mg/L median, 111 samples |
| Otematata (Hydro Village) | Waitaki District Council | THMs: no result in the release; HAAs: no result in the release; lead: not detected in 1 sample (under 0.001) | 0 in 26 | 0.82 mg/L median, 111 samples |
| Windsor | Waitaki District Council | THMs: no result in the release; HAAs: no result in the release; lead: not detected in 1 sample (under 0.001) | 0 in 13 | 1.23 mg/L median, 107 samples |
Table 7
How councils answered
Requests went to 27 councils and water companies and to the regulator on 9 August 2026 and 14 August 2026, each asking for three things: twelve months of zone-by-zone monitoring results, the chemical determinands tested, and the source and treatment process. The Act allows 20 working days. As at 15 September 2026: 15 answered in full, 5 partial, 0 charged, 7 not yet answered, and the regulator supplied an extract. The median answer took 16 working days.
| Requested from | Requested | Status | Answered | Working days | Calendar days | Statutory date (20 working days) | Note |
|---|---|---|---|---|---|---|---|
| Rotorua Lakes Council | 9 August 2026 | Answered in full | 11 August 2026 | 2 | 2 | 4 September 2026 | Full sample data for every scheme, REQ26-3110351. |
| Palmerston North City Council | 9 August 2026 | Answered in full | 17 August 2026 | 6 | 8 | 4 September 2026 | Complete lab export, 14,660 results, LGOIMA SRC0464249. |
| Tauranga City Council | 9 August 2026 | Answered in full | 18 August 2026 | 7 | 9 | 4 September 2026 | Single-zone reticulation summary plus treated-water certificates, ref A20906244. |
| Hamilton City Council (answered by IAWAI - Flowing Waters) | 9 August 2026 | Answered in full | 28 August 2026 | 15 | 19 | 4 September 2026 | A year of citywide sampling plus the July 2026 chemical screen, PFAS included. |
| New Plymouth District Council | 9 August 2026 | Answered in full | 31 August 2026 | 16 | 22 | 4 September 2026 | Four supply workbooks, no charge. The release holds no zone E. coli results. |
| Christchurch City Council | 9 August 2026 | Partial | 1 September 2026 | 17 | 23 | 4 September 2026 | Lab data supplied free; the continuous monitoring record was offered separately as chargeable. |
| Invercargill City Council | 9 August 2026 | Answered in full | 2 September 2026 | 18 | 24 | 4 September 2026 | All three parts answered, no charge. |
| Water Services Authority - Taumata Arowai (regulator, Official Information Act) | 9 August 2026 | Answered - extract supplied | 3 September 2026 | 19 | 25 | 4 September 2026 | Extract of 166,920 zone sample rows and the register of 179 notified exceedances, CAS-02102-L8X2C3. The letter states the Authority does not hold a single validated national dataset. |
| Queenstown Lakes District Council | 9 August 2026 | Partial | 14 September 2026 | 26 | 36 | 4 September 2026 | LG26-0276, answered 14 September to the 18 August refined request: field chlorine and one trihalomethane round per zone, no bacteriology, metals, pH, turbidity or fluoride. The remaining compliance results were requested on 15 September. |
| Wellington Water | 9 August 2026 | No answer yet | - | 27 so far | 37 so far | 4 September 2026 | Request sent; handled under Tiaki Wai's request 26-217, no separate acknowledgement. |
| Tiaki Wai | 9 August 2026 | No answer yet | - | 27 so far | 37 so far | 4 September 2026 | Acknowledged, request 396080. Chased 14 September; the council replied the request is substantial and still under review, no new date. |
| Dunedin City Council | 9 August 2026 | No answer yet | - | 27 so far | 37 so far | 4 September 2026 | Acknowledged, with the Governance team. Chased 14 September. |
| Napier City Council | 9 August 2026 | No answer yet | - | 27 so far | 37 so far | 4 September 2026 | Acknowledged, with Local Governance. Chased 14 September; the council acknowledged missing the statutory date and promised an estimate. |
| Hastings District Council | 9 August 2026 | Partial | 14 September 2026 | 26 | 36 | 4 September 2026 | Answered 14 September, the morning after the chaser: a scanned letter referring to an attached spreadsheet that was not attached. The spreadsheet was requested the same week. |
| Whangarei District Council | 9 August 2026 | No answer yet | - | 27 so far | 37 so far | 4 September 2026 | Acknowledged, WT2615368. |
| Waikato District Council | 14 August 2026 | Answered in full | 19 August 2026 | 3 | 5 | 11 September 2026 | ADM0101/27. The 9 August email bounced on a wrong mail domain; counted from the 14 August re-send. |
| Waipa District Council (answered by Waikato Waters) | 14 August 2026 | Partial | 1 September 2026 | 12 | 18 | 11 September 2026 | Parts 1 and 2 supplied as a lab workbook; part 3 (source and treatment) referred to the regulator's website. The 9 August email bounced; counted from the 14 August re-send. |
| Kapiti Coast District Council | 14 August 2026 | Answered in full | 27 August 2026 | 9 | 13 | 11 September 2026 | Full Hinekorako compliance export, OIR 2627/58. |
| Timaru District Council | 14 August 2026 | Answered in full | 31 August 2026 | 11 | 17 | 11 September 2026 | Response letter and testing workbook, no charge. pH and turbidity referred to the council website. |
| Hauraki District Council | 14 August 2026 | Answered in full | 14 September 2026 | 21 | 31 | 11 September 2026 | Charging letter on 31 August (up to $228). A refined part-1-only request went back on 6 September and was answered in full on 14 September at no charge: the council's own regulator compliance exports, metals and by-products included. |
| Matamata-Piako District Council | 14 August 2026 | Partial | 2 September 2026 | 13 | 19 | 11 September 2026 | Most of the data supplied; the remainder and the treatment process quoted at up to $228 including GST. |
| Kaipara District Council | 14 August 2026 | Answered in full | 2 September 2026 | 13 | 19 | 11 September 2026 | All three parts answered, no charge, ahead of the statutory date. |
| Masterton District Council | 14 August 2026 | Answered in full | 7 September 2026 | 16 | 24 | 11 September 2026 | Letter dated 7 September, received 8 September; all three parts, no charge. |
| Waitaki District Council | 14 August 2026 | Answered in full | 14 September 2026 | 21 | 31 | 11 September 2026 | OIA 1756, answered 14 September: a year of lab and field results for 25 zones plus sample-point locations; the treatment process itself is not described. |
| Selwyn District Council | 14 August 2026 | No answer yet | - | 22 so far | 32 so far | 11 September 2026 | Request sent. |
| Horowhenua District Council | 14 August 2026 | Answered in full | 11 September 2026 | 20 | 28 | 11 September 2026 | Ref 1429, answered 11 September: all three parts for five supplies, no charge. |
| Kawerau District Council | 14 August 2026 | No answer yet | - | 22 so far | 32 so far | 11 September 2026 | Request sent. |
| Thames-Coromandel District Council | 14 August 2026 | Answered in full | 10 September 2026 | 19 | 27 | 11 September 2026 | Answered 10 September: fourteen months of lab exports for every zone plus a source and treatment document, no charge. |
Working days are counted after the day the request was sent, Monday to Friday, excluding public holidays. "So far" rows are counted to 15 September 2026. Where a council is still inside its statutory date that is what the table shows. Status words are taken from the request ledger: "answered in full" means every part of the request was answered without charge; "partial" means some parts were supplied and some refused, referred elsewhere or quoted for; "charged" means a charging letter arrived instead of data.
Method
How this report was built.
The same rules as every district page in the library. Nothing is rounded up, nothing is inferred, and a below-detection result is never treated as zero.
The requestsOne template to every council: twelve months of zone-by-zone monitoring results, the chemical determinands tested, and the source and treatment process, under the Local Government Official Information and Meetings Act. The regulator was asked under the Official Information Act for the same at national level.
The readingsEach figure in tables 1 to 3 is the highest result in the release for that supply over its stated period, with the sample count beside it. A "less than" lab result is a below-detection result, not a zero. Totals are the lab's own printed total where one exists, otherwise the sum of quantified species, and every page says which.
"Adjusted" valuesThe regulator's extract carries an "Adjusted Sample Value" that turns a "less than" result into 0 and holds a "greater than" result at its ceiling. The national page uses that convention because it is the regulator's. The council tables on this page do not: a below-detection result stays below detection.
The two barsThe legal bar is New Zealand's maximum acceptable value from the 2022 drinking water standards: lead 0.01 mg/L, fluoride 1.5 mg/L, a share-of-limit rule for trihalomethanes with the tightest single limit at 0.06 mg/L, and dichloroacetic acid 0.05 mg/L. The health bar is the EWG guideline: 0.00015 mg/L for total trihalomethanes, 0.0001 mg/L for haloacetic acids, 0.0002 mg/L for lead, each set at a one-in-a-million lifetime cancer risk (lead: children's neurological effects). "Times the guideline" is floored, never rounded up.
The countA supply counts as above a health goal when any trihalomethane, haloacetic acid or lead reading in its release sits above the EWG guideline. Fluoride and chlorine never count. Rotorua's Central and Eastern city zones count as two supplies; the instant report shows them as one combined city reading. 16 zones released without chlorine, metals or bacteria are excluded from the 140 and named below.
What the regulator's extract adds and lacks397 supplies and 595 distribution zones with chlorine (455 zones) and E. coli (590 zones) results, plus a register of 179 notified exceedances across 60 supplies, 13 of them for lead and 48 for E. coli. It lacks a full year (the 2025 sheet is 2023-11-09 to 2025-05-12, 61,133 of 61,228 rows dated February 2025; the 2026 sheet is 2025-04-23 to 2026-06-25, 105,096 of 105,692 rows dated January to March 2026), chemistry for all but 37 zones (lead for 33, trihalomethanes for 3, fluoride for 2), any PFAS determinand, and any measured value behind the register's notifications. It is used here as a cross-check and is searchable on the national record.
Exclusions, district by district
Every excluded reading is listed on its district page with the reason. A quantified by-product peak that sits below the detection ceiling of the other samples in the same series is left out rather than understated (the Ashhurst rule). Raw source water and treatment-plant results are never reported as tap water.
- Rotorua Lakes Council: nothing excluded.
- Tauranga City Council: nothing excluded.
- Palmerston North City Council: nothing excluded.
- Waikato District Council: nothing excluded.
- Kapiti Coast District Council: nothing excluded.
- Hamilton City Council: nothing excluded.
- Christchurch City Council: by-product peaks below other samples' detection ceilings left out at Birdlings Flat, Brooklands/Kainga, Central Christchurch, Ferrymead, Northwest Christchurch and West Christchurch.
- Invercargill City Council: nothing excluded.
- Matamata-Piako District Council: nothing excluded.
- Waikato Waters: 4 readings excluded and listed; 6 zones released without enough data to report (Ohaupo, Mokau, Te Kuiti, Tokoroa, Arapuni and Lichfield).
- Timaru District Council: nothing excluded.
- Kaipara District Council: 5 readings excluded and listed; 2 zones released without enough data to report (Mangawhai and Glinks Gully).
- New Plymouth District Council: 4 readings excluded and listed.
- Masterton District Council: 8 readings excluded and listed.
- Horowhenua District Council: 12 readings excluded and listed.
- Waitaki District Council: 13 readings excluded and listed; 5 zones released without enough data to report (Kurow Township, Duntroon, Bushy Creek Rural, Stoneburn and Ohau Alpine Village (Lake Ohau)).
- Hauraki District Council: 8 readings excluded and listed.
- Thames-Coromandel District Council: 4 readings excluded and listed; 3 zones released without enough data to report (Whitianga, Matatoki and Omahu).
Microplastics are not a determinand in New Zealand's 2022 standards and no release here carries a result for them. Published and maintained by No Brainer Water Co., Queenstown. Data questions, corrections and the underlying spreadsheets: hello@nobrainerwater.co.nz. Councils are welcome to correct any figure; the release it came from will be cited alongside.
WHY THE TWO BARS
Your water is safe by every New Zealand rule. Both facts are true.
New Zealand sets legal limits for what can be in drinking water, and councils meet them. The Environmental Working Group publishes health-based guidelines that sit far below those limits, because "legal" and "what you'd choose for your family" are different questions. This report shows every reading against both, names the source of each, and says plainly when a council has never tested for something at all. Then the decision is yours.