PerimeterTileInterior drain, exterior dig or neither — decided by where the water is.

Interior Drain Systems

Linear feet of drain tile, sump connection and what it does not fix.

Interior drain tile for 120 ft of footing with 10 ft of lift

120 ft of interior drain tile, 10 ft of lift
120linear feet
$6,000 – $12,000 installed · needs a 1/3 hp pump against 13 ft of head
120 ft of interior drain tile, 10 ft of lift12.6 ftTotal dynamic head12 gpmDesign flow120 ftDrain tile length
Drain tile, installed$50–$100 per linear foot · about $8,400 typical$6,000 – $12,000
Pump sizedelivers about 28 gpm at 13 ft — the rating on the box is at zero head1/3 hp
Total dynamic head10 ft lift + 0.6 ft friction + 2 ft residual12.6ft
Design flow1 in/hr of rain over a 10 ft strip along 120 ft of footing12gpm
Pump starts per hour at design flowan 18-gallon working volume — over 30 starts an hour, and a larger pit buys more pump life than a larger pump42/hr
Drain tile length120ft

Notes

  • Where 12 gpm comes from. An inch of rain an hour, falling on a strip about ten feet wide along 120 ft of footing, is roughly 12 gallons a minute arriving at the tile. That is a design figure, not a measurement — the pit refill rate beats it: plug the pump, time how long the pit takes to fill a known depth, and size from that.
  • Interior drain tile does not stop water getting in. It collects water that has already reached the footing and pumps it out. That is why it costs a fraction of excavating outside — and why it leaves the wall itself wet. If the problem is a damp wall rather than water on the floor, this is not the fix.
  • The pump rating on the box is at zero head, which never happens. A pump advertised at 4,400 GPH delivers roughly half that against 13 ft of head. Ask for the pump curve and find 12 gpm at 13 ft on it. Every sump pump in every hardware store is marketed on the zero-head number.
  • Cast iron over plastic, and a check valve that is serviceable. Cast iron housings dissipate heat and last markedly longer. The check valve stops the discharge column falling back into the pit — without one the pump moves the same water repeatedly and short cycles itself to death.
  • A battery backup is not optional in a basement that floods. The storm that fills the pit is the storm that takes the power out; those are the same event. A backup pump on its own float, with a battery, is the difference between a wet floor and a finished basement.
  • Where the discharge goes decides whether this works. At least ten feet from the foundation, sloped away, and never into the footing drain it just came from — which is a real and common installation error that recirculates water forever. In freezing climates the outlet needs a route that will not ice closed.
  • Do the outside first if you can afford it. Downspouts extended well away from the wall, grade sloped away for the first ten feet, and gutters that actually work will fix a surprising share of wet basements for a few hundred dollars. Interior drain tile is what you install when that has been done and water still arrives.

Open the full page for this calculation →

Interior drain tile and sump sizing

54 calculations · browse all