French Drain vs Sump Pump: Which Do I Need?

They do different things

A French drain is a gravel-filled trench with a perforated pipe that collects groundwater and routes it somewhere else. It is a passive system — gravity moves the water through the pipe to a low point.

A sump pump sits in a pit at the low point and lifts water up and out. It is active — it requires electricity, has moving parts, and can fail.

Most functional basement waterproofing systems use both: a drain collects the water, the pump removes it. The confusion comes from contractors selling one or the other as a complete solution when it isn't.

When you need a French drain (exterior)

Exterior French drains — trenches dug outside the foundation that intercept surface and shallow groundwater before it reaches your wall — are the right answer when:

• Water is pooling in the yard and running toward the foundation.
• Downspouts dump water close to the house and there's nowhere for it to go.
• The lot grades toward the house rather than away from it.
• A neighbor's property drains toward yours (very common on sloped lots).
• There's a specific problem area — always wet, always mossy, always soft.

Exterior French drains cost $30 – $80 per linear foot installed, with most residential projects running $2,500 – $7,500 depending on length, depth, and obstacles.

When you need interior drain tile

Interior drain tile — a French drain installed inside the basement, at the base of the wall, under or at the edge of the floor slab — is the right answer when:

• Water is already getting through the wall or coming up at the slab-wall joint.
• Exterior drainage alone hasn't solved the problem.
• The groundwater or water table is the source, not surface water.
• Exterior excavation isn't practical (attached structure, landscaping, hardscape).

Interior drain tile is typically installed as part of a full interior waterproofing system that also includes a sump pump. $4,000 – $9,000 for a full-perimeter system in a typical residential basement.

When you need a sump pump

A sump pump is the right answer when:

• Water is collecting at a low point (pit, trench, or slab-wall joint) and needs to be removed.
• You have any kind of interior drainage system (drain tile has to go somewhere).
• The basement floor is below the elevation that gravity would drain to.
• You've had flood events and need active protection.

A sump pump alone, with no drainage feeding it, is not waterproofing — it is an isolated pump sitting in a pit. It'll catch water that finds its way to the pit but it won't actively remove moisture from the rest of the basement.

The combinations that actually work

Surface water + pooling: Exterior French drain

Downspout extensions + yard regrading + exterior French drain. No interior work needed if surface drainage was the only issue.

Groundwater + water table: Interior drain tile + sump pump

Most common full waterproofing scope. Drain at the perimeter, pump at the low point, battery backup for power outages.

Combination (the most common real case): All three

Fix the exterior drainage to reduce the load, install interior drain tile + sump pump to manage what still gets through. This is typically the most durable solution.

Wall crack leaks only: Crack injection (neither drain nor pump needed)

A single crack leaking during heavy rain doesn't need drainage — it needs crack injection. Poly urethane closes the crack, stops the water intrusion, and a pump and drain aren't necessary.

The sump pump decisions that matter

If you do need a sump pump:

• Get a battery backup. The storms that make the pump work hardest are the same storms that knock power out.
• 1/3 to 1/2 HP is the typical residential size. 3/4 HP or more for high-volume situations.
• Cast iron construction outlasts plastic. Worth the extra cost.
• Discharge line freeze protection matters in Indiana. A frozen discharge line means the pump runs, fails to expel water, and overheats.
• Alarms and monitoring. A pump that quietly fails is worse than a pump that loudly fails.

What to do

A free inspection gets you a diagnosis of which water source is actually the problem, and a scope matched to it. We don't sell interior drain tile to homeowners whose problem is exterior drainage, and we don't sell exterior excavation to homeowners whose problem is a failed sump pump.