A perimeter drain, often called drain tile or a foundation drain, is a perforated pipe laid around the outside of the footing. It collects groundwater before it can push through the foundation and carries it to a sump or the storm sewer. In a region with the Lower Mainland's rainfall, it does a lot of work every winter.
Signs your perimeter drain is struggling
- Water seeping in where the basement wall meets the floor during or after heavy rain.
- Damp patches, efflorescence (white, chalky deposits) or a musty smell on lower walls.
- The sump pump runs far more, or far less, than it used to.
- Water pooling against the foundation outside, or soggy soil along the house.
- Cracks in the basement slab or walls that leak after rain.
Common causes
- Silt and soil gradually filling the pipe, especially in older systems without filter fabric.
- Tree and shrub roots growing into the perforations.
- Iron ochre, an orange slime some soils produce, coating the inside of the pipe.
- Crushed, separated or sagging pipe sections.
- A blocked connection to the sump or storm line, so water collects but can't leave.
- In older homes, clay tile or early plastic pipe that has simply reached the end of its life.
How a perimeter drain is checked
The usual way in is through a cleanout or the sump. A camera inspection shows whether the pipe is silted, root-bound, broken or just dirty, and where.
What fixes it
Silt, sludge and ochre usually come out with hydro jetting or drain cleaning through the cleanouts. Roots can be cut out. Sections that are crushed or collapsed need repair, and a system that has failed along most of its length may need replacing. The camera shows which you're dealing with before any digging is discussed.
Keeping it working
- Keep downspouts discharging away from the foundation, not right beside it.
- Make sure the ground slopes away from the house.
- Have the system flushed and inspected every few years, or after any sign of seepage.
- Keep large trees and shrubs back from the foundation.
Common questions
Is drain tile the same as a perimeter drain?
Yes, in everyday use. Older systems were made of short clay tile sections, so the name stuck even though most are now perforated plastic pipe.
Can perimeter drains be cleaned instead of replaced?
Often, yes. If the pipe is intact and the problem is silt, sludge or roots, cleaning restores flow. Replacement is for pipe that is broken or collapsed.
Who can inspect and clean my perimeter drains?
A plumber answers (604) 870-1442 24/7, and every job starts with a free estimate.