Basement Floor Drain Backing Up? What to Do First and What It Means

Stop putting water down any drain in the house. No laundry, no dishwasher, no showers, and ask everyone not to flush.

Keep people and pets out of standing water, especially if it looks or smells like sewage. If water is near outlets, extension cords, a furnace, a water heater or the electrical panel, do not walk through it to reach them. If you cannot get to the main breaker from a dry spot, stay out of the water and call 911 if anyone is in danger.

Before you clean anything, take photos and video of the water, the drain, the damaged items and the high-water mark on walls and boxes. Your insurer will want them. Then call a plumber, and the city too if yours asks you to report backups first (see below).

A floor drain backing up means water cannot get past a point somewhere between the drain and the city sewer. The pattern of the backup usually points to one of five causes.

A local clog sits in the floor drain itself or the short branch that connects it. Hair, lint and sediment build up over years. In that case only the floor drain is slow, and nothing else in the house is affected.

A main sewer line blockage is further down, in the pipe that carries everything from the house to the property line. Signs include several fixtures acting up at once: toilets gurgling, the tub draining slowly, or the floor drain backing up when doing laundry. Roots, grease, wipes, a collapsed section or a sagging "belly" in the pipe are the usual culprits.

A city main surcharge happens when the municipal sewer is overloaded, often in very heavy rain. Water pushes back up the service connection into the lowest drains in the house. If the floor drain is backing up after heavy rain and your neighbours are dealing with the same thing, this is a strong suspect.

Perimeter drain or storm problems, and sump pump failure, cause water to rise around the foundation or in the sump pit rather than through the sanitary system. The water is usually clear and smells of soil, not sewage. Our Richmond drainage, sump and perimeter drain guide goes deeper on that side of things.

In most Metro Vancouver cities, the homeowner is responsible for the sewer pipe on private property and the city is responsible for the part on city land. The City of Surrey's website, for example, states that property owners maintain the sanitary service connection from the building drain to the property line, that the city clears blockages on its side at no cost, and that the owner pays for anything on the private side.

The City of Richmond asks residents to call the city at 604-270-8721 when a toilet or sewer is backed up, so crews can investigate before you hire a plumber. Richmond also notes that its inspection chambers and manholes, often in front or back yards, must stay accessible and not be buried under gardens, decks or sheds. Surrey lists 604-591-4152 for sewer backups.

Other cities have their own rules, so check your municipality's website. If a camera shows the blockage is past your property line, that footage helps when you report it.

A camera inspection runs a small waterproof camera on a cable through the drain line, and it shows exactly what is causing the backup and where.

Common findings include root intrusion at joints in older clay pipe, grease buildup, a pile of wipes, offset or cracked joints, a sag where water and solids sit, and old cast iron that has scaled inside. Roots can be cut and grease flushed, but a collapsed section has to be repaired. If you want the line cleared first, professional drain cleaning and a camera check are often done in the same visit.

A backwater valve is a one-way flap installed on the main sewer line that lets wastewater leave the house but closes when sewage tries to flow back in from the city side. It is the main protection against a surcharge in the city main, the kind of backup that a clean pipe on your property cannot stop.

If you have one, it needs attention: debris can keep the flap from sealing, and a valve that has not been checked in years may not close when it counts. Have the access cover opened and the valve cleaned as part of regular maintenance.

One thing to know: when the valve is closed, water from your own house has nowhere to go either, so you have to avoid running water during a city backup. Requirements and permits for adding a backwater valve vary, so check with your city before installation.

Treat any backup from the sanitary sewer as contaminated. Wear gloves, boots and eye protection, keep kids away, and throw out porous items like carpet, cardboard, mattresses and drywall that soaked up sewage. Disinfect hard surfaces and dry the space quickly to avoid mould. For anything bigger than a puddle, call a restoration company.

Call your insurer early, before you throw things away. Sewer backup coverage is often an optional add-on rather than part of a standard home policy, so check your policy wording. Keep receipts, the plumber's invoice and any camera footage.

Most cases of a basement floor drain backing up on the private side come from what goes into the pipes and what grows into them. Keep cooking grease and oil out of the sink, since it hardens in the line. Do not flush wipes, even ones labelled flushable, along with paper towels or hygiene products.

If you have big trees near the sewer line or an older clay pipe, an annual check or a camera inspection every few years catches roots before they close the line. Test the sump pump before the rainy season, and have the backwater valve inspected yearly. Encano Plumbing handles drain clearing and camera work across Richmond, Vancouver, Surrey and the rest of Metro Vancouver.

If your floor drain is backing up right now, call or text (604) 764-2031 at any hour. You get one flat price in writing before any work starts. For a sewage backup at night or on a weekend, see our emergency plumber page.