What is a sump pump and what factors should you consider when buying a new system?

A sump pump sits in a pit at the low point of your basement or crawl space and moves collected water out of the house before it floods the floor. When you buy one, the factors that matter most are pump horsepower matched to how much drain it serves, whether it has a battery backup, the quality of the pit and the switch, and how the pump ties into a full drainage system. A sump pump alone does not waterproof a basement. It is the engine on the end of a drainage system, and that system is what keeps you dry.

Here is how it works. Water that gets into your basement runs to a low spot. The pit collects it. A float switch tells the pump to turn on. The pump pushes that water up a pipe and outside, away from the foundation. The pump only sees water that reaches the pit, so the drainage feeding it does the real work.

Why does water show up at your foundation in the first place? When your house was built, crews dug a hole, set the foundation, then put the soil back. That backfill is looser than the ground around it. It drains slowly and holds water against your wall. Then NH winters add frost heave, which pushes on the walls. So the water collects right where the pump needs it to go. We tie our sump into a full perimeter drain along the floor wall joint, so the water has a clear path to the pit instead of finding its way up through the floor.

What to look for when you buy

Match the pump to the job. In our Forever Dry System we run 1/2 hp per 120 feet of interior drain. Too small and the pump runs hot trying to keep up. Oversized for a small basement is wasted money. Size it to the drain it serves, not to a number on a box.

Get a battery backup. This is the one most people skip, and it is the one that saves you. The worst storms knock out power right when the water is coming in. A charged backup battery pumps about a residential pool’s worth of water, roughly 15,000 to 20,000 gallons, before it needs power again. Our backup is battery only. We do not sell a water-powered model.

Check the switch and the pit. A cheap float switch is the part that fails first. It sticks, the pump never kicks on, and you find the water the hard way. A solid pit keeps debris out of the pump so the switch stays clean.

Think about the whole system, not just the pump. A sump in a bare hole with no perimeter drain will still let water come up through the floor wall joint around it. That is why our waterproofing pairs the sump with full perimeter drainage, a 12-mil wall vapor barrier, and a dehumidifier. The pump is one part of that.

You don’t need the biggest pump on the shelf. You need the right pump on the right drain with a backup. We would rather size it correctly than sell you a unit you don’t need.

What it costs

A standalone pump swap is one thing. A full basement waterproofing system with the sump built in runs $3,000 to $30,000, and for a crawl space the encapsulation that includes a sump runs $3,000 to $25,000. What drives the number is how much perimeter drain your space needs, the condition of the floor, and whether you add a backup. We give you a free inspection and a free estimate, with a written quote within 24 hours, so you see the real figure for your house before you decide anything.

Our sump pump system carries a 3-year warranty, batteries excluded. The full Forever Dry System is guaranteed to keep your basement dry for life, and that guarantee is transferable to the next owner under our conditions. See the 603 guarantee for the details.

A quick NH note. Insurance usually treats groundwater seepage and sump failure differently from a burst pipe, so check your policy and any sump or water-backup rider with your carrier. The Insurance Information Institute explains how these coverages work [verify].

Want us to look at it?

Call us at 603-610-1770 or book your free inspection. We will tell you what your basement actually needs, and where you don’t need to spend a dime yet.

Related hubs: basement waterproofing, crawl space services, and the 603 guarantee.

Related questions

Do I really need a battery backup sump pump? If you ever lose power in a storm, yes. The power goes out exactly when the water is coming in. A charged backup battery pumps roughly 15,000 to 20,000 gallons, about a residential pool’s worth, before it needs power again. Our backup is battery only.

How long does a sump pump last? A pump is a moving part, so it wears. The float switch usually fails before the motor does. We warranty our sump pump system for 3 years, batteries excluded, and we set it up so the switch and pit stay clean to get full life out of it.

Will a sump pump waterproof my basement by itself? No. The pump only moves water that reaches the pit. Without a full perimeter drain along the floor wall joint, water still comes up through the floor. That is why our Forever Dry System pairs the sump with full drainage, a 12-mil wall vapor barrier, and a dehumidifier.

Does a crawl space need a sump pump too? Often, yes. Our crawlspace encapsulation can include a sump along with a 12-mil wall and 20-mil floor vapor barrier, drainage matting, sealed seams, and a dehumidifier, sized to what we find when we inspect it.