With another cold snap coming to Ottawa this weekend, there is a risk your pipes could freeze and burst when it warms up again.

Last week, the City of Ottawa and local firefighters warned people of bursting pipes as the cold snap ended. Plumbers and emergency crews received hundreds of calls to clean up flooding during the last weather change. 

Temperatures jumped from the –30s to hovering right around zero — extreme, even by Canadian standards. And this weekend, the thermometer is going to drop drastically.

These sudden changes in weather means the phone is constantly ringing for Dave Smythe, the owner of DS Plumbing.

Pipes burst when frozen water in the pipes thaws and begins to flow — but then runs into other, still-frozen parts of the pipe and builds up pressure, the fire department said.

Some bursts are so severe, Smythe told CBC Radio's Ottawa Morning, they have to prioritize their calls like triage at the hospital. 

The past few weeks have been rough, and he says the cold isn't over yet. 

"[Expect] at least two more cold snaps, but it may not be as severe as this cold snap."

Know where the main valve is

So, this begs the question, what can you do to stop your pipes from bursting?

"Just crank [the heat] up two or five degrees," Smythe said. "What you need to do is ensure that your entire house is open for airflow."

He suggested opening doors, cupboards, and closets to allow the air in your house to move around naturally. It may cost a few dollars more on your hydro bill, but it could save you an expensive repair bill.

If you have an older house — anything built before the 1960s — pay particular attention to the pipes. Those homes are poorly insulated, Smythe said. 

But the most important tip of all?

"You need to know where the valve is if you get a burst."

Smythe says to turn off the water as soon as that happens.

With files from CBC Radio's Ottawa Morning