How to drain a basement

You drain a basement with an interior perimeter drain tied to a sump pump, and 603 installs that as our Forever Dry System starting around $3,000 to $30,000. It catches water at the floor wall joint, runs it to a pit, and pumps it out of the house. A DIY floor drain or a coat of sealer paint feels like draining the basement, but it does not move the water pushing in under your slab. So the water comes back.

Here is how the right drain works.

Where the water gets in

When your house was built, the crew dug a hole, poured the foundation, then shoveled the dirt back in. That backfill is loose. It drains slow and it holds water against your wall. Then a New Hampshire winter shows up and frost heave pushes the wall inward. Water finds the weak spot. Most of the time that is the floor wall joint, the seam where your wall meets the slab.

So draining a basement is not about mopping the floor. It is about catching water at that joint and giving it somewhere to go.

The steps to actually drain it

A real interior drainage job runs in a few steps.

We cut a channel along the inside of the footing, all the way around the wet area. We lay perimeter drain pipe in that channel so it catches water right at the joint. Every foot of that pipe slopes toward one spot, a sump pit we dig into the slab. A sump pump sits in that pit. When water rises, the pump kicks on and sends it outside, away from the foundation.

That is the core of the Forever Dry System. Full perimeter drain. A sump pump sized at one half horsepower per 120 feet of drain. A 12-mil wall vapor barrier so wall seepage drips down into the channel instead of onto your floor. And a dehumidifier to dry the air. It is 100% guaranteed to be dry for life!

What it costs and what drives the number

Basement waterproofing with us starts around $3,000 to $30,000. Three things move that number. How many feet of wall we drain. Whether your slab is thick or has pipes and obstacles we cut around. And add-ons like a battery backup pump.

The backup matters in a storm. When the power drops, a charged backup battery can move about a residential pool’s worth of water, roughly 15,000 to 20,000 gallons. Our backup is battery, not water-powered.

You do not need every add-on. If one corner gets wet and the rest of the basement stays dry, tell us that. We will tell you if a partial run covers it. We would rather scope it right than sell you the whole perimeter you do not need yet.

When it is not a basement job

If the wet space is a crawl space, this is a different job. Crawl spaces get crawlspace encapsulation, a 12-mil wall and 20-mil floor vapor barrier with drainage matting under the floor barrier, sealed seams, a dehumidifier, and a sump. That is not the Forever Dry System. See /crawl-space-services/.

And if water is coming in because a foundation crack is open, the drain handles the water but the crack still needs sealing. That is crack injection, and you can read about it under /structural-and-foundation-repair/.

Why the cheap drain does not hold

Hydraulic cement, sealer paint, a single floor drain in the middle of the slab. They are cheap and they feel like progress. They block a little surface water. They do not relieve the pressure building behind your wall and under your floor. That pressure finds the next weak spot, and you are back where you started. We do not dig the outside of your foundation either. In our field experience that exterior fix tends to fail in about two to three years as the backfill settles. Interior drainage costs less and it stays dry.

We back the Forever Dry System with a full transferable lifetime warranty. The sump pump system carries a 3-year warranty, batteries excluded, and the dehumidifier carries 5 years. See /the-603-guarantee/.

Want the real number for your basement? We do a free inspection and a free estimate, and you get the quote within 24 hours. Financing is available through Hearth, subject to approval, and we make nothing on it.

Call us at 603-610-1770 or book your free inspection. We will find where the water gets in and price the drain that keeps it out. Read more on /basement-waterproofing/.

Related questions

Do I need a sump pump to drain a basement? Almost always yes. The drain catches the water, the sump pump removes it. A drain with nowhere to send the water just moves the puddle. Ours runs one half horsepower per 120 feet of drain. See /basement-waterproofing/.

Can I drain a basement without digging up the slab? Not for a real fix. The water comes in at the floor wall joint, so the drain has to sit at that joint, which means cutting a channel into the slab edge. Surface drains and sealers sit on top and miss where the water enters.

How long does interior basement drainage last? The Forever Dry System carries a full transferable lifetime warranty, guaranteed dry for life. The sump pump system is 3 years, batteries excluded, and the dehumidifier is 5 years. See /the-603-guarantee/.

Is an outside drain a better way to drain a basement? No. Exterior excavation costs the most up front, and in our experience it tends to fail in two to three years as the backfill settles back. Interior drainage costs less and holds.