We've taken you on a safety and taste test of Ottawa's drinking water, now we take you to the source - where science of a different kind is being used to gauge its safety.

Workers on east Ontario's rivers, streams and waterways are using an interesting method to look for pollution.

Its name? "Benthic Invertebrate Sampling."

What it involves? Digging for bugs.

Conservation groups say that certain species of invertebrates are very sensitive to pollution, so they can check the purity of the water by checking their numbers.

"You can go to the Tay (River) and you have these big beautiful caddisflies," said Adrienne Lewis with the Rideau Valley Conservation Authority (RVCA). "You go to the urban streams like Sawmill and there's only three different families."

Workers put on hip-waders, bring a net and stroll the streams to check for the critters.

CTV Ottawa's John Hua joined them on a search of the Tay River, which leads into the Ottawa and Rideau rivers.

"You're doing to try to dig your toes five to ten centimetres into the sub-stream to try and knock out all those bugs," Lewis told him.

She said plecoptera or "stone flies" are very sensitive to organic pollution, so finding them in the Tay River means it's in quite good shape.

Julia Hutton specializes in urban streams with the RVCA and said it's crucial for cities to have clean water coming in.

"If you don't have good water quality in the tributaries, it's hard to achieve good water quality in the Rideau, and the Rideau feeds into the Ottawa," she said. "So everything feeds into something else."

Hutton said if you live by the water you can help keep the water supply clean by building at least a hundred feet away from the shoreline, growing plants along the water's edge as a buffer and avoiding toxic products that can flow into the water.

"It's habitat for birds, habitat for fish, habitat for benthics," Lewis said. "It's important that we maintain our streams for the future generation."

With a report from CTV Ottawa's John Hua