A sump pump is the last stage of a drainage system: water is collected by perimeter drains, arrives at a low point, and the pump lifts it out of the house. On its own, a pump in a hole is not a drainage system — it only removes water that reaches it.
What a Complete Installation Looks Like
A basin set at the lowest point, deep enough that the pump cycles sensibly rather than switching on and off every ninety seconds, which is how pumps die young.
Perimeter drainage feeding it. Perforated pipe in gravel around the inside of the footing, sloped to the basin. Without this the pump waits for water to find it by chance.
A pump sized to the job, with a float switch that cannot jam against the basin wall — a surprising share of pump failures are a stuck float rather than a dead motor.
A discharge line that goes somewhere sensible. Far enough from the house that the water does not simply run back, not into the sanitary sewer, which is prohibited in most jurisdictions, and pitched so it drains rather than holding water to freeze.
A check valve, so the column of water in the discharge pipe does not run back into the basin every time the pump stops, doubling its cycles.
Backup, and Whether You Need It
Storms cause power cuts, and power cuts stop pumps at exactly the moment they are needed. A battery backup unit runs the pump through an outage, and in a house where a flooded crawl space would damage finished space or stored belongings it is worth the additional cost.
For a bare crawl space that would simply be wet for a day, it is often not. We will tell you which situation you are in rather than adding it to every quote.
Maintenance Nobody Mentions
Pumps last between about five and ten years and they fail without announcing it. Pour a bucket of water into the basin twice a year and confirm the pump starts, lifts it, and stops. Check the discharge outside is not blocked or crushed.
If you have a crawl space humidity sensor, a sudden climb is often the first sign the pump has stopped working, which is a good reason to have one.
Cost
Installation of a basin, pump and discharge typically runs from around $1,200 to $3,500. Adding interior perimeter drainage takes the whole job into the three to eight thousand range. Battery backup adds several hundred to around a thousand.