INVERCARGILL · OFFICIAL COUNCIL DATA

What's actually in Invercargill's tap water

Invercargill City Council answered with a year of monitoring for both zones it runs - the city and Bluff - 745 samples at eighteen network sites, plus monthly chemistry at the Branxholme plant. E. coli: zero detections all year. The water is safe. It starts as Oreti River water, and the same release shows what stays in it at the tap: chlorine, added fluoride, and the by-products river water picks up from chlorination. The free check reads your address.

Official council data

Released by Invercargill City Council under the Local Government Official Information and Meetings Act 1987

Received 2 September 2026 · 745 zone samples at eighteen network sites, July 2025 to June 2026 · plus monthly Branxholme treatment-plant chemistry

THE HEADLINE NUMBERS

One river, two zones, a spotless year.

Your water passes New Zealand's rules. Invercargill City Council treats it properly - the Oreti River goes through coagulation, sand filtration, UV, activated carbon, fluoridation and chlorination before it reaches you - and their own results show it. The same results show what stays in the water at the tap. All measured. All inside the legal limits. The trihalomethane totals still sit hundreds of times above the EWG health guideline. The numbers are below; what you do about them is up to you.

0

E. coli detections in 477 samples

Zero E. coli and zero total coliforms, city and Bluff, all year. Not one bacteria test came back with a detection.

0.0372mg/L

Bluff's THM total

Stirling Point, May 2026. Inside NZ's limits. 248 times the EWG health guideline.

0.72mg/L

Fluoride, typical

Added deliberately at the Branxholme plant, peaking at 0.85. No whole-house filter removes it - reverse osmosis does, at the kitchen tap.

ZONE BY ZONE

What was found in your zone

Chlorine, pH, turbidity and the bacteria tests run year-round at eighteen network sites; metals every six months and chlorination by-products each quarter at the council's two zone codes. These are the results, straight from the release. Typical figures are the year's medians; peaks are the highest single sample.

Zone	Chlorine, typical	THMs, highest sample	E. coli	Worth knowing
Invercargill city	0.51 mg/L	0.0286 mg/L	0 in 378 samples	copper and zinc traces, well inside limits
Bluff	0.52 mg/L	0.0372 mg/L	0 in 99 samples	copper 0.022 mg/L at the Service Centre, inside the 1.3 health goal

Source: Invercargill City Council LGOIMA response, received 2 September 2026. Chlorine typicals are zone medians, July 2025 to June 2026; pH ran 7.7 and 7.6 typical, turbidity 0.36 and 0.5 NTU typical. THM figures are the highest per-sample total from the May 2026 quarterly round, summing quantified species only (bromoform sat below detection throughout); the lab's own per-species compliance ratios check out. Every haloacetic acid species came back below detection. Metals: lead, mercury, cadmium, chromium, antimony and nickel all below detection in both zones. Fluoride is measured in treated water leaving the Branxholme plant, which feeds both zones - 0.72 mg/L median across fourteen monthly samples, one November sample at 0.08. All readings sit inside New Zealand's legal limits. The pipeline booster site between the city and Bluff is excluded from zone figures. No PFAS or microplastics tests anywhere in the release.

WHAT THIS MEANS FOR YOUR HOUSE

Three things to know.

River water, thoroughly treated

The Oreti River works through the whole Branxholme treatment train - coagulation, sand filtration, UV and activated carbon among the steps - and the operator's record is genuinely clean: not one E. coli or coliform detection in 477 samples. What treatment leaves behind is the point of this page - chlorine, fluoride, and the by-products below.

By-products, highest in Bluff

Chlorine meeting river organics forms trihalomethanes. The city's May 2026 samples ran 0.0179 to 0.0286 mg/L; Bluff, at the end of the line, reached 0.0372 at Stirling Point. Inside the legal limits, 248 times the EWG health guideline - both true. Haloacetic acids came back below detection everywhere.

Fluoride is added on purpose

Fluoridation is a listed step in the plant's own process, and treated water left Branxholme at 0.72 mg/L typically. One November sample read 0.08, so the dose does move. Bluff drinks the same water. Only reverse osmosis removes fluoride - around 90%, at the kitchen tap.

YOUR ADDRESS

This is the city picture. Get the report for your home.

The free water check takes about two minutes, and it includes the PDF water report for your address - written from the same release, read for your house.

Check my water - free

THE SYSTEM THAT FITS

What we'd fit in Invercargill.

Fluoride, THMs and microplastics only come out at the kitchen tap with reverse osmosis, and that's the ES60's job. If it's the chlorine in your showers that bothers you, that's a whole-house filter - we supply those by arrangement, so call us on 021 709 370.

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INVERCARGILL WATER QUESTIONS

Straight answers.

Yes. Fluoride addition is part of the Branxholme treatment plant's own process, and treated water leaving the plant carried 0.72 mg/L typically across fourteen monthly samples, peaking at 0.85. One November 2025 sample came back at 0.08 - dosing low or off that day. Bluff drinks the same Branxholme water. No whole-house filter removes fluoride; reverse osmosis removes around 90% of it.

Yes - and the bacteriological record is spotless: zero E. coli and zero total-coliform detections in 477 samples across the city and Bluff for the whole year. Safe and pure are different questions though: chlorine, fluoride and trihalomethanes are still in the water at the tap, and the THM totals sit far above the EWG health guideline.

0.51 mg/L typical in the city and 0.52 in Bluff, peaking at 0.89, across 745 samples at eighteen network sites in the year to June 2026. The legal limit is 5 mg/L. Chlorine's job ends at your tap - a whole-house carbon filter takes it out where the water enters your house.

Trihalomethanes form when chlorine meets the natural organic matter in river water, and the Oreti River is Invercargill's source. The May 2026 samples ranged from 0.0179 to 0.0286 mg/L in the city, and Bluff's Stirling Point sample reached 0.0372 - inside New Zealand's limits, and 248 times the EWG health guideline. Every haloacetic acid species came back below detection.

The Oreti River, treated at the Branxholme plant: screening, pH correction, coagulation, rapid sand filtration, UV, activated carbon, fluoridation and chlorination, with extra UV-based oxidation in summer for taste and odour. The city and Bluff are the two supply zones, both fed from Branxholme. The free water check reads your address and sends the report for your zone.