Drinking water

Water from the Turitea catchment is of high quality, but not safe enough to use directly from the source. This is common in natural run-off from bush catchments.

Our treatment plant removes any colour, algae and silt, and ensures the water is free from bacteria and protozoans.

Water is chlorinated to neutralise some naturally forming tastes and odours caused by hydrogen sulphide. Fluoride is added at Turitea and at our bores. The level of fluoride in the water is maintained at between 0.7 and one part per million.

A local accredited laboratory keeps a close eye on the water quality from all our sources. Regular tests and samples are collected daily in different parts of the city for microbiological analysis.

Read the latest water quality report(PDF, 125KB)

Read the latest analytical report on fluoride in drinking water(PDF, 90KB)

Recent changes to legislation are seeing changes to how we need to treat water from our bores in the future.

We need to treat all water to make sure it’s safe for everyone to drink. We clean the water through a variety of treatment processes, and one step we use is chlorination which disinfects the water and kills any bacteria remaining. This is a common treatment method used all around the world and the amount of chlorine needed is tiny - just 0.2 parts per million.

In November 2021, the new water regulator Taumata Arowai required there to be a longer period of time for the chlorination of water to occur before it is pumped into the network. This is called ‘contact time’.

Our Turitea dams and our bores at Ashhurst, Longburn and Bunnythorpe supply more than 60% of the city’s water and water from these sources already met the new standards due to our treatment process or recent upgrades at these sites. One of our bores at Papaioea Park also has UV reactor which does the same thing as chlorine, so the water from this bore also meets new standards.

Only three bores in the city don’t meet the new standards for how long the chlorine is in the water before it goes into the pipe network. They are at Roberts Line, and two separate bores at Papaioea Park (we have three underground bores at this site). We have switched these bores off from use while we work on options to ensure this water meets the new requirements. During our Long Term Plan process we will prepare programmes to ensure that work is done to ensure they meet the new requirements.

By switching these bores off, it means that all drinking water currently being provided in our city meets the new drinking water requirements.

It’s important to note that these changes to legislation are not only affecting Palmerston North, but most of New Zealand cities who are also now working on solutions to also make sure they’re also compliant with the new rules. Our city has invested in our water assets over time to ensure we have a resilient network. That work has meant that we can continue supplying our city with the same amount of safe drinking water they’ve always had.

Read more about our report to council about water compliance.

You can also watch the committee meeting discussion.

The Turitea Stream has a catchment area of about 2,400 hectares. The average rainfall is 1,400 mm per year. This area is run under the Turitea Reserve Management Plan.

A reservoir has been formed at the lower end of the catchment by constructing a dam across the stream valley. The storage capacity of the dam is 1.7 million cubic metres – which meets the city's average daily use for about 60 days.

Turitea produces water quality equal to the best conventional plants in the world.

The plant was substantially upgraded in 1999 and most of its functions are now automated.

Manual tasks include monitoring production, maintaining and calibrating online technical instruments, and replenishing chemical stocks.

In times of peak demand, like weekday mornings, the main pipes from Turitea aren’t enough to supply the volume of water needed.

To meet this demand, we draw groundwater to boost mains pressure. It comes from wells, or bores, which are up to 250 metres deep. Each bore has its own pumping station. These pump drinking water through the network to your homes after it has been through a treatment process.

Under the New Zealand Building Code, water from the water network must not be able to return – or ‘backflow’ – to the system.

Backflow is dangerous when there is a cross-connection between a drinking water supply and a source of contamination or pollution. For example, a garden hose being left on in a bucket that has chemicals in it. 

There are cases where the public water supply has been contaminated with dangerous chemicals and other pollutants, causing illness. Simply because people weren’t aware of backflow.

How you can stop backflow

At home, you can reduce the risk of backflow by fitting an inexpensive hose tap vacuum breaker on outdoor hose taps. Available from your local plumber. 

Commercial prevention measures

Commercial buildings with potential hazards must have adequate backflow prevention.

This includes:

• hospitals and medical centres
• agricultural and horticultural operations
• points where portable water tankers are filled
• premises with boilers and cooling towers
• hairdressers and barbers
• some food preparation premises

If you’re not sure of the risks at your premises or business, call our Water Technical Officer on 06 356 8199.

Backflow preventer charges

Best practice: Backflow protection for hairdressing salons(PDF, 166KB)

Two-thirds of Palmy’s drinking water comes from our two Turitea Dams at the northern end of the Tararua Ranges.

The Upper Dam is a traditional concrete arch dam, which contains the bulk of our stored water. This dam then feeds the lower dam, which is an earth embankment style dam. It is the lower dam that feeds water to the Turitea Water Treatment Plant. It also maintains a constant flow to the Turitea Stream.

In 2001, we commissioned a small 200kW hydroelectric power station on the Upper Dam. Four turbines or generators are powered when water flows between the two dams. They operate at full capacity in winter – when the Upper Dam water level is consistently high. This generates enough electricity to power the entire treatment plant. Surplus electricity is sold back to the national grid.

In summer, the plant is switched to water-saving mode and most electricity is sourced from the grid. During these drier periods, water from the Upper Dam is only released to maintain the water level in the Lower Dam and a minimum flow in the Turitea Stream.

Some plumbing fittings have the potential to allow minute traces of metals to accumulate in any water standing inside them overnight.

We have a fluoride-free water tap that draws water from the park’s bore for residents who prefer to drink water without fluoride added. The water from this tap is not chlorinated.

The tap is located at Papaioea Park entrance on Featherston Street, and it is available from 6.30am to 9pm. 

We add chlorine to our drinking water to kill harmful bugs and ensure it’s safe to drink.

This disinfection process is required by government regulations. Councils must maintain a minimum chlorine level of 0.2 mg/L in the water supply network, which is known as residual chlorine.

Sometimes, when chlorine levels are close to this minimum level, the smell or taste of chlorine may still be noticeable. While this can be unpleasant for some, the water remains completely safe to drink. People’s sensitivity to taste and smell varies, so some may notice chlorine more than others.

We’re aware that some parts of our network occasionally experience stronger chlorine odours. To address this, we regularly clean our pipes and are identifying long-term projects to further improve water quality.

If you’d like to reduce the taste or smell of chlorine:

• Boil the water for 15 minutes.
• Leave the water uncovered for 24 hours.
• Consider installing a water filter for drinking water or your entire household supply.

Calcium is a naturally occurring mineral salt found in many drinking water supplies. It dissolves easily in water.

In Palmerston North, calcium levels typically range from 4 to 40 mg/L depending on the water source. Bore water tends to have higher levels as water is drawn from deep below the ground. These amounts remain well within New Zealand’s guideline value of 100 mg/L, which means our water is always safe to drink.

When water is heated, calcium can form deposits inside kettles, hot water cylinders, or on tapware and glass. Over time, these deposits can build up, becoming unsightly or affecting appliance performance in extreme cases. This is a common occurrence worldwide and not specific to our water supply.

While councils are not required to remove calcium under current regulations, you can manage deposits by:

• Soaking kettles or stained tapware in vinegar to dissolve the build-up.
• Installing a water filter to reduce calcium if you experience significant build-up.