Drinking water safety during flooding – important information for Hautere/Te Horo water supply residents

The Kāpiti Coast District Council has been in touch with residents on the Hautere/Te Horo water supply, with important information about their drinking water quality during prolonged flooding of the Ōtaki River. Information recently provided outlines that in the future, they could be advised to temporarily boil their drinking water as a precaution during long or severe flooding of the Ōtaki River.

Group Manager Infrastructure Services Sean Mallon says this is about putting precautions in place to safeguard this community, who are in a unique situation when it comes to their water supply.

“We’re constantly working to make sure our community has a safe and reliable drinking water supply. During prolonged flooding the water we collect from the Ōtaki River to fill the Hautere/Te Horo bores can get so turbid (dirty-looking) that we can’t be 100% confident that the treatment plant will kill all micro-organisms that could be in the water.”

“While the risk of this occurring is very low, it’s important we have measures in place to keep people safe.”

“If we do have prolonged flooding that has the potential to compromise the quality of the water we supply to Hautere/Te Horo residents, we may need to advise them to boil their drinking water as a precaution, to make sure it continues to be safe to drink.”

“Right now these residents don’t have to do anything. Any need for them to boil water would be clearly communicated to them if and when it’s required. A boil water notice would only be issued after careful monitoring and consultation with Regional Public Health.”

The water supply in this community is unique in Kāpiti because the water comes from bores that are closely connected to the Ōtaki River.

“The water taken from the bores can take less than a day to travel there from the river. Other bores across the District aren’t as directly linked to rivers so it takes longer for the water to travel through the ground. For example, the water in the Ōtaki public supply bores can take 13 months to travel there, and this natural filtering is a very effective first barrier that filters micro-organisms and turbidity.”

“While the ground water taken from the Hautere bores is also initially filtered by this natural barrier, there’s still a slight chance micro-organisms could get through this first natural barrier. That’s why we have treatment processes that kill anything that could get through.”

“The challenge is when the river is in flood and the water is turbid (dirty-looking), because this can decrease the effectiveness of our treatment, especially for protozoa. Our testing of the river water hasn’t shown any evidence of protozoa to date, however it’s important to recognise that we might need to take additional precautions in the future to manage this small residual risk.”

Detailed questions and answers can be found at https://www.kapiticoast.govt.nz/boil-water-notices

If residents have any concerns or questions, they should contact the Council on 04 296 4700 or email kapiti.council@kapiticoast.govt.nz

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