Toilet overflow: how to stop it and clean up safely

Stop the water in seconds

1. Turn the shut-off valve behind or beside the toilet clockwise until it stops.
2. If the valve is stuck, take the lid off the tank and lift the float, or push the flapper down over the hole at the bottom.
3. Do not flush again.
4. If neither works, shut the main water valve for the house or unit.

What kind of water is it?

The cleanup depends entirely on this.

Clean water. A cracked tank, a failed supply line or a fill valve that would not shut off. The water came from the supply, not the drain. Treat it like any other clean leak.

Bowl water, no waste. An overflow from the bowl after a clog, with only water in it. This is grey water. It carries bacteria and needs disinfecting, but hard surfaces clean up well.

Bowl water with waste, or a drain backing up. If waste came over the rim, or water is also rising in the tub, shower or floor drain, this is sewage. A backup at several fixtures means the blockage is in the main drain or the sewer, not the toilet.

If you are not sure, treat it as contaminated.

Protect yourself

• Rubber gloves and waterproof footwear
• Eye protection if there is any splashing
• Keep children and pets out
• Wash hands and arms thoroughly afterwards
• Wash the clothes you wore separately in hot water

Cleaning up a contaminated overflow on a hard floor

1. Remove solids with paper towel or a scoop into a sealed bag.
2. Mop up or wet-vacuum the liquid.
3. Wash the floor, the base of the toilet, the lower walls and baseboards with detergent and hot water.
4. Apply a household disinfectant and leave it wet for the time stated on the label.
5. Rinse and dry.
6. Disinfect the mop, bucket and wet vacuum, or discard the mop head.

Disinfectant does not work on dirty surfaces, so wash first.

What cannot be cleaned

Porous materials that absorbed contaminated water should be removed:

• Bath mats, unless they can be washed in hot water
• Carpet and underpad
• Swollen baseboard
• Drywall that wicked the water up
• Particleboard vanity bases
• Cardboard and paper

Where the water went

A toilet overflow rarely stays in the bathroom.

• Under the flooring. Water gets under vinyl, laminate and tile edges and into the subfloor.
• Into the walls. It runs under baseboards and wicks up drywall.
• Through the floor. In an upstairs bathroom, it comes out through the ceiling below, around light fittings and at seams.
• Into the next room. Under the door and under the wall plate.

A ceiling below that is stained, sagging or dripping needs attention. Wet ceiling drywall and insulation above it have to be dried or removed, and if the water was contaminated the affected materials are replaced.

When to call a professional

• Sewage is involved over more than a small area
• Water reached carpet, got under flooring or went through to the level below
• It ran for more than a few minutes
• Several fixtures backed up at once
• Anyone in the home is at higher risk from contamination

Fixing the cause

• A simple clog: a flange plunger, then a toilet auger.
• Repeated clogs: something is lodged, or the drain line has a problem.
• Several fixtures backing up: the main drain or sewer lateral. Call a plumber, and report it to the municipality if you suspect the city sewer.
• A tank that will not stop filling: replace the fill valve and flapper.

Do not use chemical drain openers in a clogged toilet. They rarely work on a blockage and leave caustic water in the bowl for whoever plunges it next.

Insurance

Sudden overflow from a fixture is commonly covered under the water damage section of a home policy. A backup from the sewer needs the sewer backup endorsement. Photograph the damage before cleaning up.

Toilets on a septic system

In rural homes, a toilet that overflows or drains slowly along with other fixtures can mean the septic tank is full or the bed is saturated, particularly after heavy rain or a spring thaw. Stop using water in the house and call a septic service. Pumping the tank relieves the immediate problem, and the cause still needs to be found.

Basement toilets

A basement toilet is the lowest fixture in most houses, so it is where a sewer backup shows first. If it overflows while nobody is using it, or during a rainstorm, the water is coming from the sewer and not from the toilet. A backwater valve on the main drain is the protection against this. See backwater valves in Ontario.

What a professional cleanup involves

• Extraction of the water
• Removal of contaminated porous materials, bagged for disposal
• Cleaning and disinfection of the floor, walls and fixtures
• Moisture readings in the floor, the walls and the ceiling below
• Drying equipment until readings return to normal
• A record of the work for your insurer

Children, bath toys and clogs

A large share of household toilet clogs come from things that should not be flushed: wipes labelled flushable, paper towel, cotton swabs, dental floss, sanitary products and small toys. A covered bin in the bathroom, and a word with younger children, prevents most repeat overflows.

More: sewage backup cleanup.