Castlecliff water network sand removal begins
Published on 14 October 2026
Whanganui District Council has today begun a staged programme to remove sand and sediment from the Castlecliff water network, following successful trials of specialist filtration equipment, including a trial within the live network yesterday.
The trial demonstrated sand could be removed from the network using the specialist filtration system while maintaining safe water supply to connected properties.
Whanganui Mayor Andrew Tripe says the council is prioritising the safety of the water supply as it works to resolve the issue, with the successful trial being a significant step forward and providing confidence to begin work across the wider network.
“This week’s successful trial is a significant step forward in addressing the sand issue. It gives us confidence to begin working through the wider network, while continuing to take a careful and methodical approach to avoid disturbing sand and sediment in other areas.”
The affected network has been divided into six areas, with work planned to progress one area at a time following yesterday’s trial. Results will be assessed before moving to the next area, allowing the council to adjust the approach if required. While the programmed work is an important step forward, the council is not yet in a position to confirm when the work will be completed.
The NO-DES mains cleaning creates a temporary loop through hydrants, circulating water through filters before returning it to the network. This is the first time it has been used in Whanganui, although it has been used by other water providers in New Zealand and Australia to remove sediment from drinking water networks. It also reduces the amount of water released onto streets and into stormwater.
“We’ll monitor the effectiveness of NO-DES as work progresses through the network and keep the community informed. We’re also providing schools, industry and plumbers with practical information about what to expect, what they need to know and how we can help. Our focus is on making careful progress, getting this right and supporting the community throughout.”
Mayor Andrew acknowledges there has been ongoing disruption for the community from this unprecedented event for Whanganui.
“We recognise how frustrating and disruptive this has been for affected households. This week’s result is encouraging, but we know there is still work ahead of us. Our focus is on progressing that work as quickly and safely as possible while continuing to support the community. We appreciate how understanding and patient the community has been.”
Feedback from residents at last weekend’s drop-in session visits reinforced the importance of resolving the issue and continuing to provide practical support to affected households.
The issue emerged after water-main upgrade work in early September, when higher water flows appear to have disturbed sand and sediment in a reinstated part of the network at Westmere reservoir. The issue has been intermittent, with some households experiencing sand, sediment or discoloured water.
The council continues to use specialist advice to guide the staged work, monitoring and next steps.
“Disruption to households and businesses has been at the forefront of our minds when planning this work, however we cannot guarantee that people won’t notice changes to their drinking water while the work is underway. We encourage the community to contact the council if they do notice any changes such as sand, sediment, or discolouration,” says Mayor Andrew.
Residents may see crews and equipment near hydrants, with some noise or short-term traffic and parking changes. Access to businesses and residents will be maintained.
The council will check water pressure, flow, clarity and chlorine levels before, during and after the work. Regular water testing continues to show the water is safe to drink. Residents will be told immediately if this changes.
NO-DES is working in the following neighbourhood today: Raupo Street, Tiki Street, Miro Street, Lee Street, Titoki Street, Ruapehu Street, Karyn Street, Kowhai Street, Mosston Road, Puriri Street.
Frequently asked questions
What should I do if I notice anything unusual with my tap water while this work is underway?
If a household or business notices sand, sediment or discoloured water, run the outside or garden tap closest to the road frontage for at least 10 to 15 minutes. If the water does not clear, stop and contact the council on 06 349 0001 so the team can follow up and provide support.
Please also contact the council if you notice low or no pressure, or problems with taps, filters, hot-water systems, plumbing or household appliances.
When you call, provide your address, tell us what is happening and when it started. Let us know if you need drinking water or other support.
Please contact the council directly rather than posting on Facebook, so our teams can follow up.
Is a water tanker still available?
Yes, a water tanker is available daily between 10.00am and 4.00pm at the Surf Club, Castlecliff Beach. Please bring your own clean containers.
If your household needs water and you are unable to collect it yourself due to an accessibility issue, we suggest you ask whānau or friends to collect water from the water tanker and deliver it to you. Alternatively, please call 06 349 0001 and we will arrange delivery.
What should I do if an appliance or plumbing is affected by this issue?
The council can arrange support if sand or sediment has affected household plumbing or appliances. Contact us before arranging non-urgent work, as reimbursement is limited to eligible costs directly related to this issue.