Saskatoon's environmental advisory committee is asking the city to move ahead with green roofs.

The idea is to plant vegetation on roofs so that when it rains, the water stays there and doesn't end up in the sewer system.

Saskatoon's sewer system gets flooded from time to time when there have been heavy downpours — and sometimes the sewage backs up into people's basements, causing major damage.

"What green roofs do is they provide a sink for storm water," Sean Shaw said.

"In a rain event, in the summertime, between 60 to 90 per cent of rain would be captured by that green roof and held rather than flushed directly out into the sewers."

The committee is recommending a pilot project to try out the green roof concept on certain city facilities or perhaps commercial developments.

If the pilot works out, there could be a bylaw developed some day that would require green roofs on all commercial buildings over a certain size, the committee says.

The green roof idea is just one of a series of ideas the committee has on managing storm water. As that water can carry gasoline and heavy metals into the river, the committee wants Saskatoon to start tracking what goes into the storm drains.

"Are we impacting the river or are we not impacting the river?" Shaw asked. "In the future if we do that kind of quantification, we could understand when we're actually seeing events of contamination occurring."

One change that could have a impact on many homeowners is to mandate that all downspouts and sump pump systems be disconnected from the sanitary sewer system.

Right now, that applies only to new homes, but older homes are grandfathered. The committee thinks the ban on putting storm water into the sanitary sewer should be expanded and the city should enforce it.