Residents in the Ōhaupō area just south of Hamilton are being asked to reduce their use of water urgently after a problem with a pipeline.
The issue arose following routine maintenance at Pukerimu pump station, which brings water from Waikato River to Parallel Treatment Plant for treatment before it is distributed to the community.
The Waipā District Council said it is affecting the council's ability to treat water at the plant to supply reservoirs across the Pukerimu Scheme at the usual quantities.
The council said residents could help by limiting household use and stopping all outdoor and non-essential water use.
Its water services manager Martin Mould said actions taken to reduce water use would help the reservoirs to refill over time.
"We are producing treated water at Parallel Treatment Plant but at lower quantities which means there is limited water within the scheme. We are working around the clock to isolate and resolve the issue, and we ask all residents on the scheme to please limit their water use where possible."
Water tankers are supplying water at 8 Great Collins Road, Ōhaupō, Kaipaki Hall and Roto-o-Rangi Hall near Cambridge.