The Greater Vancouver Regional District confirmed on Friday that further testing shows there is no E. coli contamination of the water supply at the University of British Columbia.

On Wednesday, a sample from one location at the Point Grey campus had tested positive for the bacteria.

At the time, health officials said they suspected it was a false result.

Further sampling showed that was the case. The GVRD says the original sample was tainted because a clogged drain had backed up at the sampling station, which was just below a composting site.

The regional district's chief operating officer, Johnny Carline, said that since the boil-water advisory went into effect last week, there has been no contamination found in any of the other water samples taken across the Lower Mainland.

End to boil-water advisory 'getting close' 

Carline says turbidity levels in the water in the Capilano and Seymour reservoirs continue to drop. But he says the boil-water advisory for Vancouver, Burnaby, North Vancouver and West Vancouver can't be lifted just yet.

"It will take probably at least 24 hours for that water to travel from the intake to the western extremities of Vancouver, and so it will still be probably a few days before we can actually lift the advisory. But it's getting close.

Carline said the turbidity levels are dropping fairly quickly, but noted they tend to plateau as they get lower.

The advisory was issued after a major storm left a lot of silt in the region's two largest reservoirs — the Capilano and the Seymour reservoirs in the North Shore mountains.

Capilano reservoir shut off

On Thursday, GVRD water manager Paul Archibald announced that water from the Capilano reservoir had been shut off because of turbidity.

He noted that water from the Seymour reservoir gets treated with chlorine for a much longer period than water from the Capilano.

He said the move should improve water quality while putting the Capilano on the "back shelf" until its turbidity subsides.

Boil-water advisories remain in place in Parksville and Port Alberni on Vancouver Island.