Keeping Grease Out of Kitchen Drains

Why it matters in Toronto homes

Grease cools as it travels, clings to pipe walls and catches food particles and soap until the line narrows. Older Toronto homes are especially vulnerable, because their kitchen drains are often galvanized or cast-iron pipe with rough, corroded interiors that grab grease more easily than smooth plastic. Long horizontal runs from a kitchen addition at the back of the house to a stack in the middle give fat plenty of time to cool. The City's sewer bylaw also prohibits putting grease into the sewer system, because it clogs city mains as well as your own.

Step-by-step what to do

1. Let pans cool, then scrape the hardened fat into a tin or straight into your organics. Toronto's Green Bin takes modest quantities of greasy paper and oil soaked up by kitchen towel.
2. Wipe out oily pans with kitchen paper first, then wash.
3. Collect liquid oils in a sealed jar or can and put it in the garbage, or take larger amounts to a City drop-off depot.
4. Fit a basket strainer so scraps stay out of the trap.
5. Run a full sink of hot water through the drain once a week to help keep the line moving.

Mistakes to avoid

• Believing a garbage disposal makes grease safe. It does not; ground food plus fat is a faster clog.
• Using chemical drain openers on a greasy line. They can damage old metal pipe and rarely clear a solid grease plug.
• Pouring coffee grounds down the sink. They bind with grease into a dense sludge.
• Assuming a slow drain is just the trap. In older homes the buildup is often several metres along the line.

If you have a disposal, our garbage disposal page explains what it can and cannot handle. For a broader list of things that cause trouble, see what not to flush.

Time to bring in a plumber

Phone us if the kitchen sink drains slowly despite a clean trap, if it backs up into the other basin or the dishwasher, or if you smell rancid odours from the drain. Professional kitchen drain cleaning with a cable or hydro jetting removes buildup from the whole line. Where the old pipe is badly corroded, replacing the kitchen branch may be the longer-lasting fix.

Holiday cooking

Kitchen drain calls rise after big holiday meals, when roasting pans, gravy and deep-fried dishes add up to far more fat than usual. Keep a dedicated container by the stove during those weeks, and scrape roasting pans into the green bin before soaking them. A little planning saves an unwelcome service call on a holiday weekend, when the sink is fullest and you need it most.

Common questions