Weeping tile connected to the sanitary sewer: why it matters and how disconnection works

01 /Why is some weeping tile connected to the sanitary sewer?

Because that is how many houses were built. For decades the simplest outlet for a foundation drain was the pipe that already ran under the basement floor to the street: the house drain. In neighbourhoods served by combined sewers, which carry sewage and rainwater in one pipe, it made little difference to the builder where the water went. Later, when cities built separate storm and sanitary mains, many houses still sent their tile to the sanitary side by gravity.

The City of Edmonton’s homeowner guide describes that sequence directly. Houses before about 1960 may have weeping tile connected to the sanitary service and a combined main; for development before 1988, weeping tile flows were directed to the sanitary and combined sewer mains; and as of 1988, new development must direct weeping tile to a foundation service where one is available. The same guide notes that this type of connection has not been allowed in Edmonton since 1988.

02 /Why does a sewer connection cause basement flooding?

Two things happen in a big storm. First, every house on the street with tile tied to the sanitary sewer is adding groundwater to a pipe that was sized for sewage. Second, stormwater leaks into sanitary systems through manholes and cracked pipes. Together they can fill the sanitary main until it surcharges: the water level in the main rises above the level of basement floor drains, and water flows backwards up the service lines into houses.

A house whose tile is tied into that system is exposed twice. Sewer water can come up the floor drain, and it can also back into the weeping tile itself and rise under the slab and against the walls. That is why a floor drain that bubbles and overflows in storms that flood the street is such a strong clue; the Weeping Tile Problem Finder weighs it heavily.

03 /How can you tell if your weeping tile goes to the sewer?

1. No sump pit in a house built before the late 1980s is the first hint that the tile drains somewhere by gravity.
2. Clear water at the floor drain during or after heavy rain, when nobody is using water, suggests tile flowing into the house drain.
3. A camera run from the building drain cleanout can show a tile connection entering the drain, often near where the drain leaves the house.
4. A flow test: with the tile flooded at a cleanout or window well drain, watch whether water arrives in the floor drain or main cleanout.
5. City records or a plumbing assessment: Toronto’s program even subsidises a one-time home plumbing assessment by a plumber (as checked September 2026).

If you find a connection, do not cut it yourself. Capping the tile without a sump in place leaves the groundwater with nowhere to go, and the work needs permits in most cities.

04 /How is weeping tile disconnected from the sewer?

1. Confirm the connection

   A camera run or plumbing assessment shows where the tile joins the drain.

2. Check the program first

   If your city subsidises the work, read its rules and apply in the required order before hiring anyone.

3. Get permits

   Plumbing or building permits are usually needed for a sump, a backwater valve and changes to the building drain.

4. Install the sump

   A new pit is cut into the basement floor near where the tile can be intercepted, with a pump, check valve and a discharge through the wall.

5. Sever and cap

   The tile is cut from the building drain and the drain opening is capped, inside under the floor or outside at the connection. Toronto’s program describes this as severing and capping the underground sewer connection.

6. Reroute the tile

   The tile is connected to the new pit so all foundation water arrives there.

7. Add a backwater valve

   With the tile off the drain, a backwater valve on the building drain can close in a surge without trapping tile water.

8. Discharge to the surface

   The pump sends water outside onto permeable ground away from the foundation, never to the floor drain or sanitary sewer.

How the pit and pump work, and how to choose a backup, are in how weeping tile and sump pumps work and sump pump choice and backup. The valves involved, including the flapper and P-trap some systems use, are covered in weeping tile backwater and flapper valves.

05 /Which cities pay toward disconnection?

Program details change, so treat the table as a starting point and check the city’s own page before any work. Figures were read from each city’s site in September 2026.

More city-by-city detail, including what each program asks for in writing, is on the Across Canada page.

06 /What should you do before booking the work?

• Read your city’s program page and note whether you must apply before, or within a set time after, the work.
• Ask the contractor to itemise the invoice by device; Toronto, for example, asks for battery backup costs to be itemised separately.
• Confirm who pulls the permits and when the inspection happens, especially for a backwater valve that must be inspected before it is covered.
• Decide where the discharge will go on your lot: onto permeable ground, well away from the foundation and neighbours, never onto a hard surface that ices over.
• Keep photographs, invoices, permits and inspection reports together for the application and for your insurer.

As a planning reference, a sump pit and pump runs about $1,500 to $3,500 and a backwater valve about $1,800 to $4,500 in CAD 2026 terms on this network; the full list is on the cost page. If you would like contractors to quote a disconnection, send HAUSE the details.

FAQQuestions people ask