Residents in Nanaimo, B.C., are being told not to use water after a powerful storm caused widespread damage Thursday.

The City of Nanaimo says the windstorm and power outages knocked out its water treatment plant so it couldn't produce water. Staff said Friday afternoon the facility has begun to produce some water but not enough to meet normal demand.

Nanaimo Mayor Leonard Krog said a generator at the plant failed. Crews were able to restore power, but are still dealing with mechanical issues — first a broken fan belt, and then faults with the generator's electrical circuits.

"This is a major issue for the city and its citizens," Krog said. "We know that many Aboriginal communities across this country face that on a constant basis and I wouldn't wish it on anyone."

B.C's Auditor General Carole Bellringer releases an audit report, the findings of which she says causes her "grave concern". (CBC)

Nanaimo has a population of 105,000.

The city is asking residents to curtail all water use, including laundry, showers, bathing, washing cars, running dishwashers and other non-essential uses.

"We're asking people not to use water until further notice," Krog said. "No flushing or anything."

The city says the water is safe to drink, but has to be conserved for firefighting. It's not yet known when the generator will be restored.

City pools and arenas are closed until further notice. The city says the pool's showers and bathrooms aren't useable and that arena staff aren't able to clean the ice.

"It's going to be enormously difficult for businesses for families, for care facilities, for all of the people who rely on the safe clean water," Krog said.

"It's pretty hard to tell people to shut down their businesses when it's often the most beneficial time to be in business."

A tree leans against a home in Nanaimo, B.C. after a severe windstorm hit Vancouver Island on Thursday. The city has been asked to conserve water as a power outage has damaged the local supply plant. (Twitter/NickBoykiw)

"Crews are working hard to resolve this issue and we will provide updates as information becomes available," said Bill Sims, director of engineering and public works with the city.

"People are heeding [the restrictions]. We're noticing that consumption is down. So that's great, really good news."

Businesses impacted

At Food Koma in Downtown Nanaimo, employee Ibrahim Herwi is hopeful the situation will improve soon.

Some restaurants have modified their menus and service because of the restrictions.

Staff at Food Koma say they have had to make changes because of the restrictions. (CBC)

"We're just being cautious on how we are going to use it. We are not going to let the taps run or anything," Herwi said.

"If we have to wash we will do it quickly and we are going to fill up a bucket of water with soap so we can use the soap water."

Joanne Hogan, a 21-year resident of the city, said the situation has been made worse because no one had time to prepare.

"A lot of people didn't get essential things yesterday because the stores were closed," Hogan said. "There were lineups already for fuel last night. Everywhere I tried to go, the lineups were massive."

A sign posted outside a restaurant as Nanaimo grapples with water restrictions. (CBC)

Salt Spring Island supply damaged

Meanwhile, on Salt Spring Island, downed trees that damaged the community's water infrastructure have affected some parts of the island's water supply.

"There are two boil advisories on two small systems on Salt Spring Island, but not all of it, although we are asking all residents to conserve water at the moment on the whole island," said a statement from Andy Orr with the Capital Regional District.

Until water service is restored, officials have issued a boil water advisory for the Fernwood part of the Highland-Fernwood water system.

Residents in the area should boil their drinking water until further notice, say officials.

The community has a population of 10,700.