Residents in the Foxton and Foxton Beach areas are being told to turn off their sprinklers and hoses.
The Horowhenua District Council has asked everyone to reduce their water use to ensure demand does not exceed supply.
Water supplies are under a "Level 2 restriction", the council said, which means the use of sprinklers, soak hoses, irrigation of parks and gardens, hosing of paved areas and windows and cars is forbidden.
Houses with even street numbers can use handheld hoses, watering cans or buckets on even dates, and those with odd street numbers can use them on odd calendar dates.
Windows and cars can only be cleaned using a bucket or watering can filled from a tap.