Sump Pump Checks Before the Wet Season

What the pump does

A sump pump sits in a pit, usually in the lowest part of a basement or crawl space. Water drains toward the pit from the surrounding soil or from a drain tile system. When the water reaches a set level, a float switch turns the pump on, and the pump pushes the water out through a discharge pipe that carries it away from the house. When the level drops, the float turns the pump off again.

Because the pump only runs when water rises, a fault can stay hidden for months. A pump that has stopped working will not announce it, and the first sign is often a wet floor during a storm. That is why a short check before the rainy and snowy months is worth the time.

Test it with a bucket of water

Pour a bucket of water slowly into the pit, and watch what happens. The float should rise, the pump should start, and the water level should drop until the pump shuts off at the bottom of its cycle. Listen for a smooth run without rattling, grinding or humming without movement. If the pump does not start, check the power at the outlet and the position of the float. If it starts but does not clear the water, the pump may be clogged or worn.

Do not run the pump dry for long stretches. If the pit empties and the motor keeps running, shut it off and refill the pit before testing again.

Check the discharge line outside

A pump can work perfectly and still fail to protect the basement if its discharge line is blocked. Walk outside and find the end of the discharge pipe. Look for leaves, mud, sediment or a buildup of ice. The water should exit at a point that slopes away from the foundation, so it does not run back toward the house. Run the test again while you watch the outlet. A steady stream should leave the pipe, and it should not flow back toward the walls.

In winter, a discharge line that ends in a low spot can freeze and back water up into the system. If you live where the ground freezes, ask a provider about the best place to route the outlet before the cold sets in.

Check the check valve and the float

Most pump systems have a check valve on the discharge line. Its job is to keep water from falling back into the pit after the pump stops. If the valve is stuck open or missing, water drains back, and the pump starts again and again in a short, repeating cycle. Listen for a pump that turns on, runs briefly and turns off, then turns on again within a minute or two. That pattern points to the check valve or to a leak in the discharge line.

Look at the float as well. It should move freely on its arm and should not catch on the pit wall, a pipe or a loose cord. A float that sticks in one position may leave the pump off while the water rises, or leave it running when the pit is already empty.

Plan for a power outage

Pumps tend to be needed most during storms, and storms are when power often fails. Many homes have a battery backup pump or a backup system that runs when the main power is out. If yours has a battery, check the manufacturer's guidance on the battery's age and replacement, and test the backup the same way you test the main pump. Make sure the backup has a working float and that its battery is charged. If you have no backup, know how you would remove water if the power went out overnight.

Keep the pit and surroundings clear

Check the lid or cover of the pit. A cover keeps debris, small objects and the family's curiosity out of the pit, and a clean pit makes it less likely that the float will catch. Remove any sediment from the bottom of the pit with a bucket, and make sure the area around the pit is not used for storage that blocks access.

Signs that something needs attention

• Water rising in the pit during dry weather, which can point to a supply or drain problem rather than surface water
• The pump running much more often than it did in the past, especially when it has not rained
• A pump that makes a new grinding, rattling or humming sound
• Damp spots on the floor near the pit or along a wall, even when the pump is working
• A musty odor in the basement that comes and goes with the pump cycle

Rising water during a heavy storm can be normal, as long as the pump keeps up and the level falls afterward. What matters is whether the water drains away. If the pit keeps filling in dry weather, or if the pump works in the test but the basement stays damp, the water may be coming from a pipe or a hidden line rather than from surface drainage. Our basement leak detection page explains how providers separate seepage from a pipe leak, and the hidden pipe leak detection page covers leaks inside walls and floors.

When to call

Call a provider if the pump does not start during the bucket test, runs constantly, cannot be cleared at the discharge line, or fills faster than it empties. Call as well if you find water with no clear source after the pump has been checked. If the water appears to come from a supply line under the floor or the yard, our water bill spike checks guide shows how to confirm a meter leak, and the water line leak detection page explains how those lines are traced. Reach a local provider who serves your area by calling (708) 221-8167. Have ready the date of the last pump service if you know it, a description of how the pump behaved during your test, and a photo of the discharge outlet if it is safe to take one.

A short checklist

1. Pour a bucket of water into the pit and confirm the pump starts, clears the water and shuts off.
2. Walk outside and clear the discharge line, then confirm the outlet slopes away from the house.
3. Listen for short, repeating cycles that suggest a check valve problem.
4. Confirm the float moves freely and the pit lid is in place.
5. Test any battery backup and make sure it is charged.
6. Call (708) 221-8167 if the pump fails or the basement stays damp in dry weather.