Discoloured water

Sometimes you might notice water from your tap that smells strong, or looks yellow, orange, brown, or cloudy. We know this can look worrying, but we assure you it’s temporary and not a health risk.

Here’s why it happens, what you can do, and what we’re doing to fix it.

What to do if your water is discoloured

Run your outside cold tap for up to 20 minutes.
Postpone doing laundry until the water runs clear, so it doesn’t stain your clothes.
If it doesn’t clear, call us on 06 356 8199 and we can flush nearby pipes.

Read this factsheet to find out more about why we get discoloured water in Palmerston North and what we’re doing about it.

Discoloured water factsheet(PDF, 754KB)

What to do if your water smells strongly of chlorine

White or cloudy tap water

Discolouration is caused by natural minerals reacting in pipes

Discolouration in Palmerston North is due to small amounts of iron and manganese built up in pipes. While there isn’t a lot of iron and manganese in the city’s main water supply from the Turitea dam, water sourced from our deep underground bores pass through many layers of rock, sand and mineral-rich soil. These minerals can make water look yellow, orange, or brown, especially when flows and pressures change in the network, or when they contact chlorine (mandated by the government to keep our water safe).

The Ministry of Health’s guideline for manganese is less than 0.4 mg/L. Palmerston North’s levels are typically around 0.01 mg/L, and we test frequently.

These minerals get dislodged in pipes

Over many years, a thin layer of biofilm can form inside pipes and trap tiny amounts of iron and manganese. Since 2022, higher chlorine doses to meet national safety standards act like a stronger cleaner or disinfectant and can dislodge this film, briefly discolouring the water.

Chlorine reacts with these minerals

Slightly increased chlorine in bore supplies react with iron and manganese, which causes the minerals to clump into tiny specks that accumulate in our pipes and cause brownish water to appear at the tap. They may look odd, but they’re not harmful.

About 40 percent of the city’s water comes from bores. This is the main cause of discolouration seen around the Railway Road, Keith Street and Papaioea bores. These bores supply areas including Kelvin Grove, Roslyn, Papaioea, Terrace End and Milson. Tākaro has had fewer reports. In Ashhurst and Bunnythorpe, reports of discolouration pre-date the new standards, which is why solutions in those areas are happening quicker than other parts of the city.

How you can reduce the taste or smell of chlorine

We must legally maintain a minimum residual chlorine of 0.2 mg/L in our water network to kill harmful bugs. Sometimes, even at the minimum level, you may still notice a smell or taste. The water remains safe to drink.

To reduce chlorine taste or odour:

Leave water uncovered for 24 hours.
Consider a drinking water filter or whole-of-house filter.
Boiling water may help reduce the chlorine odour, however, the water is safe to consume without boiling.

Some parts of the network occasionally experience stronger chlorine odours.

Prefer water without taste or odour?

You can fill bottles from a tap at Papaioea Park, which has water without added chlorine and fluoride.

Due to the risk of bacteria growth over time, we recommend you thoroughly clean all bottles and containers before filling and don't store the water for a long time before you drink it.

White or cloudy tap water

Cloudy or white-looking water is usually just tiny air bubbles. When pressurised water in underground pipes reaches your tap, the pressure drops, and dissolved air comes out as bubbles. They clear from the bottom of the glass within a minute or two.

It’s not caused by extra chemicals.

We only add chlorine and fluoride as required by national regulations, and we continually monitor levels.

Changing flows (such as demand peaks, valve operations, maintenance) can make cloudiness appear occasionally.

How we keep our water network clean

Annual cleaning of the main city supply pipes

Each year, we clean one of the two main pipes that carry water from the Turitea Dam to homes and businesses in the city. This process, called swabbing, is usually done at the end of winter when the Manawatū River is in high flow. Cleaning removes mineral build-up, so it doesn’t react with chlorine or flow changes and cause discolouration.

All water mains within the city are flushed on a rotating yearly schedule. The two main pipes are flushed in alternating years. We’re also gradually replacing older pipes made from materials such as cast iron and replacing them with more modern plastic ones.

A giant sponge is used to clean the pipes

We isolate sections of the main pipe, insert a large sponge (called a swab), then use water pressure to push it through. The swab cleans as it travels. Near the river, we retrieve the sponge and flush the loosened material under strict consent conditions to protect our awa (river).

What we're doing now

Targeted flushing

We flush pipes in key locations on a rotating schedule and in response to calls.

Long-term improvements

Filtration plants at bores

A sand-based filter was commissioned in Ashhurst in 2025 that filters the water through different layers of material to remove any minerals before the water goes into the supply pipes. We’re planning to install these filtration systems at bore sites in Railway Rd, Keith St and Papaioea Park. These plants cost several million dollars per site, so installing them across the city will take several years.

Pipe renewals

We’re gradually replacing older concrete mains with plastic pipes to reduce build-up.