Sump Pumps in Canadian Homes: How They Work, Where the Water Should Go, and What to Ask Before You Buy

A basement that stays dry through spring melt and heavy rain usually owes it to two things: drains around the foundation and, in many houses, a sump pump that lifts the collected water out. When the pump fails or the water is sent to the wrong place, the result is a wet basement or a problem for the neighbours and the municipal sewer. This guide explains the basics in plain language. It is general information, not a substitute for your local rules.

What a sump pump does

Foundation drains (often called weeping tile) collect groundwater around the footing. Where that water can run by gravity to a sewer, ditch or other approved outlet, no pump is needed. Where it cannot, the drain empties into a pit (the sump) in the basement floor, and an automatic pump lifts the water out when the level rises.

A City of Medicine Hat, Alberta, safety codes bulletin (August 2023) describes it this way for new homes with one or two dwelling units:

A sump pit is not mandatory if the excavation shows no sign of potential water ingress and the foundation drains can drain to a sewer by gravity.
A sump pit is required where gravity drainage is not feasible, for example with walkout foundations, or where a high water table is found.

The bulletin also states that bulletins do not overrule the National Building Code - Alberta Edition. Other provinces use their own code editions, and this article does not cover them; check yours with your municipality.

What the pit and pump need, according to that bulletin

The bulletin cites the 2019 Alberta code and the 2020 National Plumbing Code for these points:

The sump pit has a minimum depth of 750 mm and a minimum area of 0.25 m2.
It has a cover designed to resist removal by children and to be airtight.
Where gravity drainage is not practical, an automatic pump discharges to a sewer, a drainage ditch or a dry well.
The discharge pipe needs, in order in the direction of flow, a union, a backwater valve and a shut-off valve.
The pump gets a dedicated branch circuit with an outlet permanently labelled as a sump pump receptacle, placed near the pump.

These are the rules quoted in one Alberta city's bulletin. They are not a complete checklist, and your province, city or inspector may require something different.

Where the water goes matters

The Town of Cobourg, Ontario, publishes a short info sheet with practical rules that are common sense in many places:

Discharge outside, away from the foundation, to your yard, a ditch or a storm sewer, far enough away that the water does not run back toward the foundation drain.
Do not connect the pump to a floor drain or laundry tub, because those lead to the sanitary sewer. Cobourg states that connecting a sump pump or foundation drain to the sanitary sewer violates the Ontario Building Code and the town's sewer by-law, and can cause sewage backup into the basement.
Do not discharge onto a neighbouring property, the sidewalk or the roadway.
Do not connect downspouts to the foundation drain. Extend them well away from the house.
Protect the discharge hose from freezing; if it goes to a ditch, bury it below the frost line.
Install a back-up battery for power failures.

The info sheet gives no minimum distance from the foundation, so do not assume a number. If you suspect an illegal connection in your house, the sheet advises contacting a plumber.

Choosing and sizing: questions to ask

We do not quote prices or recommend products here. Instead, take these questions to a licensed plumber or a supplier:

How much water does my pit usually receive, and when (spring melt, summer storms)? Ask the installer how the pump was sized, not just which model.
What happens in a power failure? The Cobourg sheet recommends a battery back-up. Ask how long a given back-up system can run and how often it should be tested.
Is the pump automatic? A bulletin point above notes a sump for a non-automatic pump must hold 24 hours of accumulation, which is rarely practical. An automatic float or switch is the usual approach.
Where does the discharge pipe end, and is it routed so that it cannot freeze or flow toward the foundation?
Is the cover on tight? The airtight cover keeps soil gases and humidity out of the room.

[AD_SLOT]

When to call a professional

Work involving electricity, plumbing connections, the backwater valve or changes to the foundation drain belongs with licensed trades. Rules and permits differ across provinces and cities, and an incorrect connection to the sanitary sewer can cause serious problems for you and your neighbours. Insurers and municipalities may have their own requirements; ask them before you start.

What this guide could not verify

Code editions currently in force in each province.
Municipal rules in cities other than those named above.
Any pump brand performance, battery run time or price.
Whether your area offers a flooding-protection subsidy. Some municipalities do, but we have not verified any outside Quebec (see our Quebec guide).

Quick checklist

Confirm local rules with your municipality before any work.
Discharge outside and away from the foundation, never to the sanitary sewer.
Keep downspouts off the foundation drain.
Plan for power failure with a back-up.
Protect the discharge line from frost.
Use licensed trades for plumbing and electrical work.

Request a quote

Planning a sump pump installation or replacement? Tell us briefly about your project and we will pass your request to qualified local contractors.

[QUOTE_BUTTON]

General information only, not professional or legal advice. The official codes, your municipality and the manufacturer's instructions apply.