Why Your Basement Floor Drain Smells

Dry traps

Floor drains have a trap that holds water to block sewer gas. If the drain isn't used, the water evaporates and the smell comes through. Pour a litre or two of water into the drain every few weeks.

Furnace and heating season

A dry, heated basement in winter makes trap water evaporate faster. Check floor drains more often during heating season.

Cleanout caps

A loose or missing cleanout cap on the main line lets gas escape. Make sure the cap is in place and tight.

Blocked vents

Plumbing vents on the roof let sewer gas out above the house. Snow, ice or debris can block them, causing gurgling drains and smells inside.

Backups and slow drains

If the floor drain smells and also gurgles or backs up when the washer drains, the main line may be partly blocked.

Get help

If the smell continues, see drain cleaning or sewer and septic lines.

Trap primers

Some newer homes have a trap primer, a small device that tops up the floor drain's trap automatically. If your drain still dries out, the primer may not be working. A plumber can check it or suggest one for a drain that rarely gets used.

Mention the details

When you ask for help, say when the smell is worst, whether the drain gurgles and whether it's been used recently. Those clues help the plumber find the cause quickly.

Vacant homes and cottages

In a house or cottage left empty for weeks, every trap can dry out, not just the floor drain. Run water in each sink, tub and drain when you return, and pour a little into the floor drain before you leave again.

More plumbing guides

• Getting Your Pipes Through a Moncton Winter
• The Spring Thaw and Your Basement
• Finding Your Main Shut-Off Valve
• How Old Is Your Hot Water Tank?
• Checking a New Brunswick Plumber