If your basement is prone to flooding, should you install French drains, a sump pump, an ejector pump, or all three?

For a basement that floods, you want interior perimeter drainage plus a sump pump. You do not need an ejector pump. An ejector pump moves sewage and gray water from below a sewer line, so it does nothing for groundwater flooding. The exterior French drain most people picture is the weak fix. The pair that keeps a basement dry is an interior drain line feeding a sump pump, which is the core of our Forever Dry System. We install that full package starting at $3,000 to $30,000.

Why the water keeps coming back

Water pools against your foundation for a plain reason. When your house was built, the crew dug a hole, set the walls, then put the dirt back. That backfill is loose. It drains slowly and holds water right next to your foundation. Add a New Hampshire winter and frost heave pushes those walls inward over time. So the soil around your basement is basically a bucket. Rain and snowmelt fill it. Pressure builds. Water finds the floor wall joint and pushes in.

That is why a quick patch never lasts. You are fighting water that has nowhere to go.

French drains: the right idea, the wrong place

A French drain just means a gravel trench with a perforated pipe that carries water away. The idea is sound. The problem is where most people put it.

An exterior French drain means digging down the outside of your foundation and burying pipe in that backfill. In our field experience that fix tends to fail in about two to three years. The trench clogs with silt. The backfill settles. You paid to dig up your yard and the water comes back. Nik calls it a poor fix.

The drain that lasts goes on the inside. We cut a channel along the inside edge of your basement floor, lay drainage pipe, and run every drop to a low point. That low point is your sump.

Where the sump pump comes in

The sump pump is the engine. Water collects in a pit, the pump kicks on, and it sends that water outside and away from the house. We size it to the job, roughly a half-horsepower pump per 120 feet of interior drain. For most homes one pump handles the whole basement.

We pair it with a battery backup. Power goes out in the storms that flood basements, and a plug-in pump is useless without power. A charged backup battery keeps pumping while the power is out, which buys you a lot of runtime when the lights are off. The backup is battery only. We do not run a water-powered backup.

So do you need an ejector pump?

Probably not, and this is one to skip. An ejector pump is for a different problem. It lifts sewage or wastewater from a bathroom or laundry that sits below your main sewer line up to the drain. It does nothing for groundwater. If you are flooding from rain and snowmelt, an ejector pump is the wrong tool. Do not let anyone bundle one into a waterproofing quote unless you are also adding a below-grade bathroom.

What the full fix includes

Our Forever Dry System is the basement package: full-perimeter interior drainage, a sump pump with battery backup, a 12-mil wall vapor barrier so wall seepage drops to the drain, and a dehumidifier to pull the damp out of the air. It is 100% guaranteed to be dry for life! The warranty is transferable under our conditions. See the details on our 603 guarantee.

If your problem is a crawl space instead of a finished basement, that is a different build called crawl space encapsulation, and it runs starting at $3,000 to $25,000. If you have cracks letting water in along the wall, those are a foundation repair item, not a drainage one.

What drives the cost

Price tracks the size of the basement, how many feet of drain you need, and how many pumps the layout calls for. A small basement with one pump sits at the low end. A big, wet, multi-pump basement runs higher. The full waterproofing build starts at $3,000 to $30,000. We give you a free inspection and a written estimate, and you get a quote within 24 hours. If you want to spread it out, we offer financing through Hearth, subject to approval, and we make nothing on it.

We are local. We serve New Hampshire, Maine, and Massachusetts, and we have done this work for more than 5,000 homeowners in New England.

Want a real answer for your basement? Call us at 603-610-1770 or book your free inspection and we will tell you exactly what your basement needs.

Related questions

Will an exterior French drain fix my flooding for good? In our experience it usually does not. Exterior drains buried in loose backfill tend to clog and settle within about two to three years. Interior perimeter drainage feeding a sump pump is the durable fix.

Do I really need a battery backup on my sump pump? Yes. Basements flood during storms, and storms knock out power. A plug-in pump cannot run without electricity. A charged backup battery keeps pumping when the grid is down.

What is the difference between a sump pump and an ejector pump? A sump pump removes groundwater that collects in a pit below your floor. An ejector pump lifts sewage or wastewater from a fixture below the sewer line. Flooding is a sump pump job.

Can you just fix the crack instead of installing drainage? If water is coming through a single crack and not the floor wall joint, crack repair may be enough. Foundation crack injection starts at $1,000 to $3,000. We will tell you which problem you actually have when we inspect.