A water emergency has been declared on part of the Tsuu T'ina First Nation, just southwest of Calgary.

A watermain break has disrupted potable water service on the east side of the reserve and people are advised to not drink the tap water.

A Tsuu T'ina First Nation spokesman, Peter Manywounds, said service has been affected to 55 houses as well as a daycare, the local recreation centre and the administration building.

"The warm weather and the thaw, you know, and it's a pressure line," he said. "A whole bunch of factors kind of enter into what occurred."

Manywounds said the band is working with the City of Calgary to repair the water line. Water service in that part of the reserve comes from the city's system.

A truck with potable water is at the North Sarcee Townsite playground so people can fill up water containers. Drinking water is also being provided at the fire hall.

Manywounds said they hope to restore water service as soon as possible but there's no firm estimate on when the line will be fixed.

The reserve does have a contingency plan in place and may move some residents to another location if the fix isn't completed today.