Tararua District Council has issued a boil water notice for residents on the Dannevirke water supply due to a detection of E.coli.
A council spokesperson said the boil water notice would continue for three days while further testing is under way.
The council is testing in partnership with Taumata Arowai to ensure testing is accurate and done as quickly as possible.
An update would be provided on April 27, the spokesperson said.