More than two million residents of B.C.'s Lower Mainland have been told to consider boiling their water in the wake of the big storm that blew through the area on Wednesday.

The Greater Vancouver Regional District issued the advisory Thursday, warning that the brown, cloudy tap water increases the risk of gastrointestinal illness.

The GVRD said the heavy rains of the past couple of days have increased turbidity in the Capilano and Seymour reservoirs on the North Shore.
 
Vivianna Zanocco of the Vancouver Coastal Health Authority said that turbidity is at unprecedented levels.

"Usually we're at about a one rating, which is normal. One of the reservoirs is at an 80, another is at 40," she told CBC News.

"Normally it doesn't make it less safe if you see a little bit of that, but when you get to this level, what happens is it interferes with our ability to disinfect the water and so we can't kill the bacteria because the dirt coats the bacteria."

The GVRD says people should use boiled or bottled water for drinking, brushing teeth and washing fruit and vegetables. It's not clear how long the boil water advisory will remain in effect.

Lights coming back on

B.C. Hydro crews are slowly restoring power to thousands of homes and businesses across B.C.'s South Coast.

Hydro expects to have most of the outages restored by the end of day, but warns that more isolated areas might not get their lights back until Friday.

High winds knocked down trees and damaged homes in West Vancouver.
(CBC)

More than 200,000 Hydro customers lost electrical power during Wednesday's storm that tossed trees onto power lines and dumped enough rain to push rivers to near flood levels.

The storm swept through the area on Wednesday, with winds of more than 100 km/h. Among the areas hit the hardest were Surrey, Langley, Abbotsford and Maple Ridge.

More than 80 people were forced to leave their homes in the Seascape subdivision near Horseshoe Bay in West Vancouver because of the danger of falling trees.

So far, they have not been allowed back as emergency officials continue to assess the situation.

The storm is also believed to have caused a four-storey building under construction in East Vancouver to collapse.

The bigger the trees, the harder they fall

In West Vancouver, residents said they were not surprised that a huge windstorm would cause such damage. The winds caused trees to fall onto power lines and homes. Five trees fell on property belonging to Michael Evans, with one leaning on his roof.

A BC Hydro crew surveys damage caused when the steel frame of a building under construction in Vancouver collapsed during a storm Wednesday.
(Richard Lam/Canadian Press)

"You know, it's Mother Nature's way of dealing with the trees in West Van," Evans said. "We love our trees, we protect our trees, but we allow them to grow ridiculously large, considering we string up all our power in trees. I mean, we can't have it both ways."

Areas hit hardest on Vancouver Island included Port Alberni, where the town was cut off on Wednesday because of highway closures to both the east and west as a result of flooding and fallen trees.

That prevented additional repair crews from getting into the town to restore power.

However, the road was reopened Thursday, and Port Alberni is slowly getting back on its feet.

The Island community has also issued a boil-water advisory.

There are also several other road closures on northern Vancouver Island, cutting off the communities off Gold River and Tahsis.

With files from the Canadian Press