Sump Pump Maintenance and Battery Backups

Sump pump maintenance and a battery backup go together because the pump usually fails at the worst moment: during a heavy storm, when the hydro is out and water is pouring into the pit. Test the pump every few months by filling the pit with water, clean the pit once a year, and add a battery backup pump so the basement stays protected through an outage. The whole routine takes about twenty minutes.

How a sump pump protects the basement

Weeping tile around the foundation collects groundwater and carries it to a pit in the basement floor. When the water in the pit rises, a float switch turns the pump on and it pushes the water up a discharge pipe and out to the yard. If the pump does not start, the pit overflows onto the floor. In the clay soils around London, water drains slowly and the pit can fill quickly in a spring melt or a summer downpour.

Sump pump maintenance: how to test it

1. Check the power. The pump should be plugged directly into a grounded outlet, not into an extension cord or power bar. If the outlet has a test and reset button, confirm it has not tripped.
2. Lift the pit cover and look inside. Remove gravel, silt, toys and anything else that could jam the float or clog the intake.
3. Slowly pour a bucket or two of water into the pit. The float should rise, the pump should start, and the water level should drop quickly.
4. Listen. A healthy pump hums steadily. Grinding, rattling or a pump that runs without moving water points to a worn or blocked impeller.
5. Watch what happens when it shuts off. You should hear the check valve on the discharge pipe close. If the water you just pumped runs back into the pit, the check valve needs replacing.
6. Go outside and find where the discharge line ends. Confirm water came out, the end is not buried or blocked, and it empties onto ground that slopes away from the house.

Do this test in early spring, before summer storm season and again in the fall. Run it more often if your pit takes in water regularly.

Yearly cleaning and common failures

Once a year, unplug the pump, lift it out and rinse off the screen at the intake. Scoop the sludge out of the bottom of the pit. Check that the float moves freely and cannot hang up on the pit wall or the cord. A stuck float is one of the most common reasons a working pump never turns on.

In winter, the discharge line is the weak point. If the end of the pipe freezes solid, the pump runs against a blockage and water has nowhere to go. Keep the outlet clear of snow and make sure the line slopes so it drains after each cycle.

Pumps wear out. Many last somewhere around seven to ten years, less if they run often. If yours is in that range, runs noisily, cycles on and off rapidly or has visible rust, replace it on your schedule instead of during a storm. Write the install date on the discharge pipe with a marker.

Battery backup options for a sump pump

A standard sump pump runs on household power. Storms that fill the pit are the same storms that take out hydro, so a backup is worth having in any finished basement or any house where the pit runs regularly.

• Battery backup pump. A second, separate pump sits in the pit a little higher than the main one and runs off a deep-cycle battery kept charged by a wall unit. It takes over if the power fails or if the main pump quits for any reason. This is the most common choice.
• Water-powered backup. This type uses municipal water pressure to draw water out of the pit, so it needs no battery. It only works on municipal water, uses a lot of it while running, and has specific plumbing requirements, so talk to a plumber about whether it is allowed and suitable.
• Generator. A portable generator can run the main pump, but only if someone is home to start it. A permanently installed standby generator starts on its own and also runs the furnace and fridge.

How to choose and look after a battery backup

Run time depends on the battery size and how often the pump cycles. A backup that cycles occasionally can last through a long outage, while one that runs nearly nonstop will drain much sooner. If your pit fills quickly in storms, buy the larger battery. Choose a system with an alarm that sounds when the backup is running or the battery is low, and one that can send an alert to your phone if you are away often.

Test the backup when you test the main pump. Unplug the main pump, fill the pit and confirm the backup starts. Batteries lose capacity with age and typically need replacing every few years, so follow the manufacturer's schedule. Keep the terminals clean and note the battery's install date.

Your next step: go downstairs with a bucket today and run the test. If the pump hesitates, makes noise or is older than you can remember, plan the replacement and the backup together.

Common questions