# How to pump water out of a basement with a drainage pump

> Which drainage pump a basement needs, how to make a sump pit with automatic pumping and a float switch, and where to discharge the water.

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*June 17, 2026*

![Diagram: flooded basement, drainage pump with a float switch and a hose led outside](https://watertrade.com.ua/uploads/articles/basement-drainage.jpg)

In spring and after heavy rain, water can come into the basement every year. While you look for the cause and waterproof the walls, the water has to be pumped out — preferably automatically, so you do not have to stand guard with a bucket.

## What the diagram shows

1 — the drainage pump, 2 — the float switch, 3 — the discharge hose led away from the house.

## Which pump you need

- **For clean or slightly dirty water** (snowmelt, groundwater) — a drainage pump handling particles up to 5–10 mm.
- **For dirty water with silt and sand** — a dirty-water pump passing particles of 25–35 mm.
- **Head** — the basement depth plus the hose length (1 m of head per 10 m of hose) plus a margin. Usually 7–10 m is enough.
- **A float switch** — essential if the pump has to work by itself.

## DIY automatic pumping

1. Make a sump pit at the lowest point of the floor — about 50×50×50 cm, with the walls lined with a concrete ring or concrete. Water will collect there.
2. Put a brick or a tile on the bottom of the pit and stand the pump on it — it will suck up less silt.
3. Adjust the float cable length: the pump should start before the water rises out of the pit and stop while a little water still covers the casing.
4. Connect the discharge hose or pipe and fit a check valve on the outlet so the water in the hose does not run back.
5. Discharge the water well away from the foundation: into a storm drain, a ditch or lower ground — but not towards the neighbours.
6. Connect the pump through an RCD — in a basement with water it is a must.

> The float must not catch on the pit walls or the cable — otherwise the pump will run dry or not start at all.

Test it once a season: pour water into the pit and make sure the pump starts and stops by itself. See our pumps section for drainage pumps.

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