An incident at one of the major water treatment plants in the St. John's area has sent a worker to hospital and resulted in an urgent plea from City Hall for people to curb water use.

A worker at the Bay Bulls Big Pond Water Treatment plant was injured in a fire in the electrical room and taken to hospital.

The plant is now unable to produce water, so City Hall is warning residents to limit their water use to emergencies.

Major commercial users of water are being told to stop operations until further notice.

Discretionary uses of water, such as washing dishes, laundry and bathing are also now prohibited.

The water rationing involves people in St. John's, Mount Pearl, C.B.S., Paradise and Portugal Cove-St. Phillips.

The city doesn't know when the plant will start producing water again.