Before you start: stay dry and keep your hands out
- Stand on a dry floor. The CDC says never to turn power on or off or use an electric tool or appliance while standing in water.
- Don't touch a breaker or fuse with wet hands or on a wet surface, per the Electrical Safety Foundation International.
- Never put your hands in the pit while the pump is plugged in. Unplug it first if you need to clear debris.
- If the basement has flooded and water reached outlets or the pump, don't test. ESFI says keep the power off until an electrician inspects the system.
- If the outlet looks scorched or the breaker or GFCI trips when the pump starts, stop and call an electrician. Don't keep resetting it.
Step 1: Look before you pour
Find the outside end of the discharge pipe first, and make sure it isn't buried in leaves or snow. Then look at the pit. The Building America Solution Center says the float must move freely, and a cord, loose part or the pit wall can catch it. Note whether there is a check valve on the discharge pipe; BASC says its job is to keep pumped water from running back into the pit when the pump shuts off.
Many pits have a gasketed, bolted-down lid, which BASC recommends to keep moisture and soil gases, including radon, out of the house. If your lid is sealed or connected to a radon vent pipe, don't pry it off; look for an inspection port, or have the installer or a radon contractor open and reseal it.
Step 2: Run one full cycle
Pour clean water slowly into the pit, through the inspection opening if there is one, keeping it away from the plug and cord. Use a bucket and keep pouring until the float rises. Let the water lift the float. Don't lift it by hand to fake the test.
- Starts: the pump should switch on as the water rises, without help.
- Drains: the water level should drop steadily, not just hum.
- Stops: the pump should shut off once the water is down.
- Stays off: if water rushes back into the pit and the pump restarts right away, the check valve may not be holding.
If the water keeps rising and the pump hasn't started, stop pouring before it gets near the top.
Step 3: Check the outside end
Have someone stand outside while the pump runs. Water should come out of the pipe and keep moving away from the house. BASC warns that dumping it next to the foundation just recycles it back into the foundation drainage, and that discharge should go to a storm sewer, a dry well or out and away from the house. FEMA adds that the pipe should run on sloped ground so it drains and doesn't freeze. For winter routing and frozen lines, see where a sump discharge line should send water in winter.
What the results tell you
- Doesn't start: the float may be stuck, the pump may be unplugged or tripped, or the switch or motor may have failed. Check that the float is free and the outlet has power (from a dry spot), then call a plumber or sump pump technician.
- Runs but the water doesn't drop: possible clogged intake, failed impeller, or blocked or frozen discharge pipe. Unplug it, stop the test and have it checked.
- Water flows back and the pump restarts: ask about the check valve.
- Water pools by the foundation outside: the discharge needs to go farther or somewhere else.
- Everything works: write down the date and what you saw, and put the lid back exactly as it was.
What this test doesn't prove
One bucket shows the pump turns on and moves water. It doesn't prove it can keep up in a long storm or during snowmelt, and it doesn't test a battery backup pump, which needs its own test from its manual. If the basement still gets damp when the pump works fine, read sump pump or dehumidifier: which problem each solves and interior drainage or exterior waterproofing.