Residents of Pt Howard in Lower Hutt must boil water before drinking, cooking or brushing their teeth with it.
A slip last night caused a loss of pressure or supply to Howard Rd, Church Lane, Nikau, Westhill and Ngaumatau Rds.
Wellington Water says about 165 properties either have no water or their supply could be contaminated.
“The slip is also restricting access for repair crews to restore service quickly. Water tankers are available at Marine Drive and 53 Howard Rd.”
The agency hopes to restore water and access later today.
Wellington Water earlier said a burst water pipe caused last night’s slip and when it was assessed this morning it had dislodged a power pole.
Cordons are in place and the area from 21 Nikau Rd and 40 Howard Rd has been closed.
Limited foot access is available past the top of the slip for residents who wish to stay at home, although people affected by cordons and water outages should consider finding alternative accommodation with friends and family, the Hutt City Council said.
Ten car parks at the bottom of Howard Pt have been reserved for residents so they can walk up.
The 19-year-old disappeared without her wallet or mobile phone.