A district council is installing dozens of isolation valves on a water system to help solve the mystery of massive water loss.
Ruapehu District Council says 40 isolation valves will help identify leaks or high points of use, including possible illegal commercial water intakes from Ōhakune’s reticulated network.
The council is also considering using thermal imaging to find underground leaks on private properties as the holiday town battles to stem the unexplained loss of 720,000 liters (720 cu m) of water every day from the network.
In June last year, the council said the volume of water missing was equivalent to filling the township swimming pool two and a half times a day.
*Mackenzie’s water consumption is significantly higher than most districts
* Waimate District Council installs 1400 water meters to reduce drinking water losses
* Ability to know your water consumption before houses that consume too much are charged
Reducing unexplained water loss was essential to manage future demand – including the growth of services in new residential developments – and to avoid preventive boil water advisories.
Boil water advisories are issued when the council is unable to provide water that meets drinking water standards. This is a particular problem during periods of heavy rain and busy school holidays when poor raw water quality reduces drinking water production and there is not enough treated water stored to handle the high demand.
Infrastructure services manager Stuart Watson said reducing overall water demand and reducing leakage losses from 20,000 liters per hour to 10,000 liters per hour would give Ōhakune the best chance of avoiding a boil water advisory during these times. It would also help meet water resource consent limits and enable the Ōhakune water treatment plant to serve much-needed new housing, he said.
Chief executive Clive Manley said water savings of between 5,000 and 10,000 liters per hour (5m3 to 10m3 per hour) had been achieved over the past year thanks to an awareness campaign keep on going. The campaign is asking people to report leaks diligently because porous volcanic soils allow water to flow underground, making leaks difficult to spot.
Residents are also offered free plumbing worth $200 per job to fix household leaks and drips.
“We’ve had 48 people taking free plumbing so far, and we’re pleased with that response,” Manley said.
The council’s water contractor Veolia has repaired all network leaks discovered as a result of the free plumbing offer and all other known water network failures have been resolved, he said.
“To achieve half the required water saving is important, but we still use more water than we should in theory.”
Manley said the council is now investigating the possibility of informal catches or illegal commercial uses.
“We are working methodically to identify these informal outlets where people have dipped into pipes and drawn water that we are unaware of. Some practices may have been in place for years.
“We should know who is taking water. We will then discuss with these users and work with them to regulate water withdrawals. We’re not going to shut down businesses, it’s more about figuring out who’s taking the water.
Manley said the council is carefully working on a strategy to target illegal commercial use at network edges.
“We asked water staff to walk around the rural/outdoor parts of the network looking for unusual connections. This helped identify a number of practices that would consume a significant volume of water.
“These users were contacted, resulting in behavioral changes at the time. We maintain continuous monitoring of these situations.
Isolation valves would allow the flow of water to be controlled in smaller areas of the reticulated network in order to identify what was happening in those isolated sections.
“Veolia has identified the exact locations within the network for the facilities,” Manley said.
Work did not continue immediately because water modeling was needed beforehand to plan for the development of new housing.
“This modeling is now completed and calibrated according to potential new housing developments. The cost of the works has been budgeted for this financial year 2022/23, where we plan to install around 40 new isolation valves.
“This will allow us to refine and better understand the request. Based on the careful data acquired from the reservoirs, demand rises and falls throughout the night. This demonstrates the use.
Manley said underground leaks through private properties were a potential issue that could be explored in the new fiscal year. New thermal imaging technology could be effective in targeting this type of loss.
He said the proposed Three Waters reform had no impact on the council’s efforts to prevent the water from disappearing.
“The reform of the Three Waters is not relevant. We are required to manage our water well,” Manley said.
The council’s long-term plan includes maintaining an accelerated work program to modernize its drinking water plants within five years. One of these projects is a new water treatment plant for Ohakune.
“Producing drinking water is expensive and repairing large water losses directly affects the capacity of the plant we have to build and the amount of water we need to produce.”
Manley said there were no plans to introduce water meters for domestic users.