Bulk Water Cross Connection Project, Lower Hutt

Closing the bulk water cross connections will help ensure drinking water supplied to around 800 properties meets current Taumata Arowai drinking water requirements and further reduces the risk of contamination.

Current drinking water regulations require treated water supplies to achieve a higher level of chlorine disinfection than was required under the previous regulatory framework.

Chlorine plays an important role in the treatment process by inactivating harmful microorganisms, including bacteria and viruses, helping ensure water remains safe to drink as it travels through the distribution network.

While the water currently supplied to these properties is considered safe to drink and the public health risk is low, the supply does not fully meet current regulatory requirements.

Currently, around 800 properties supplied from the Waterloo Water Treatment Plant do not fully meet Taumata Arowai's current chlorine disinfection requirements.

While the public health risk is considered low and the water remains safe to drink, Tiaki Wai is committed to completing upgrades as quickly as practicable so the affected properties comply with current drinking water standards.

To achieve this, bulk water cross connections to the local water supply distribution network downstream of the Waterloo Water Treatment Plant needs to be permanently closed.

Closing the cross connections will ensure treated water remains within the intended treatment and storage pathway before entering the distribution network. This will help ensure the required level of chlorine disinfection is achieved and provide greater opportunity to identify and respond to treatment or water quality issues before water reaches customers.

These cross connections are a deliberately constructed connection between the bulk water system and the local distribution network. In the past, they have provided operational flexibility (helping manage through pipe bursts etc. by allowing water to be supplied by a different route etc. and keeping water supplied to the community), helping support network water pressure needs and enabled the water to enter the local network directly, rather than first passing through reservoirs.

However, it is best practice to keep water on the intended pathway (via reservoirs, rather than direct into the local distribution network from the bulk water pipe). This supports better water quality outcomes, chlorine contact time and a stable, more resilient water network.

We are working towards closing these cross connections by the end of 2026. We will keep you updated on the exact timeframe once confirmed. 

We are in the process of installing water pressure booster pumps at selected locations ahead of this change, and preparing public comms.

Modelling and trials confirm that closing the cross connection will reduce water pressure in some parts of the network.  To maintain appropriate levels of service and continue meeting drinking water standards, pressure booster pumps will be required in some locations.  

Modelling and trial closures indicate pressure boosters are required in the following locations:

• Mission Street, Waterloo
• Woodvale Grove, Fairfield
• Wyndrum Avenue, Waterloo
• Whites Line East, Waiwhetū

These pressure boosters will help maintain appropriate water pressure while enabling permanent closure of the cross connection.

These pressure boosters will be installed on council owned berms in the above residential areas.

We're expecting that most residents will not notice a change in water pressure in their homes. The water pressure will remain above minimum standards.

Chlorine is a disinfectant (helping kill germs so water remains safe to drink). To be fully effective it needs be at the right concentration level and have enough time mixed in with water. 

Effective disinfection is achieved either by having higher concertation of chlorine (within recommended levels, i.e. higher concentration for a shorter time) or a longer contact time, with the same or lower levels of chlorine. 

By closing the cross connections, we will make sure that the treated water is directed to local communities via reservoirs. This increases the time available for chlorine to do its job, supporting safe, healthy drinking water.