You want your basement to stay dry even if your sump pump fails or the power goes out in a storm. A battery backup covers both. Whether you need one depends on how hard your pump works, what is in your basement and how often your power goes out.
TL;DR
- A battery backup is a second pump in the same pit that runs on its own battery when the main pump stops or the power fails.
- The Government of Canada recommends a backup pump for homes with a sump pump.
- It matters most if your basement is finished, your pump runs often, or your area loses power in storms.
- A backup that shares the main pump's power source will stop in an outage, so it needs its own battery.
- Test it two to five times a year and care for the battery as its manual describes.
- Cost depends on the pump, the battery, your pit and how the discharge is set up.
What does a sump pump battery backup do?
A battery backup is usually a second pump in or near the sump pit. It has its own float or sensor, set to switch on when the water rises too high. So if the main pump fails, jams or loses power, the backup starts and pumps the water out.
Most kits stay plugged into your home's power so the battery stays charged, as the Government of Canada's sump pump guidance notes. When the power fails, the backup runs on the battery. Many also have an alarm that sounds when the backup runs or the battery is low.
Do you need a battery backup sump pump?
The Government of Canada says a backup pump is always recommended, because the storms that fill your pit often cut the power too. Still, some homes have more at stake than others. Use this table to see how urgent it is for yours.
| Your situation | How much a backup matters |
|---|---|
| Your basement is finished, or you store valuables, a furnace or appliances down there | High. Even shallow flooding can damage flooring, drywall and stored belongings. |
| Your main pump runs often in spring thaw or heavy rain | High. A busy pump has less margin if it fails mid-storm. |
| Your street loses power in storms | High. Without a battery, your pump stops exactly when it is needed. |
| Your main pump is near 10 years old | High. Add a backup now and plan the main pump's replacement. |
| You are often away from home | High, ideally with an alarm or monitoring so you hear about a problem. |
| Your pump rarely runs and the basement is unfinished | Lower, but still recommended. Keep testing the main pump every year. |
Battery backup or water-powered backup?
There are two common kinds of backup, and they suit different homes.
| Battery backup | Water-powered backup | |
|---|---|---|
| How it runs | A battery, kept charged from your home's power | Uses household water pressure to draw water from the pit and discharge it outdoors |
| Works in a power outage? | Yes, until the battery runs down | Yes, as long as you have water pressure |
| Main limit | Run time depends on the battery and how much water comes in | Uses municipal water the whole time it runs |
| Important consideration | In long outages, the battery has to be sized for how much water your pit takes in | Needs suitable water pressure, the right plumbing connections and approved backflow protection. Most homes on a well are not a fit, because stored pressure runs out after an outage. |
Ontario's plumbing rules require protection that keeps pit water out of your drinking water. Ask your plumber whether a water-powered backup is allowed and suitable before you buy one.
How long does a battery backup run?
It depends on the battery's size and condition and how much water flows into your pit. A battery that lasts many hours when the pump runs now and then may last much less in heavy rain.
Before you buy, ask how long the backup can run at the rate your pit fills. If outages in your area last a long time, ask about a larger or second battery.
Capacity matters too. A backup pump may move less water than your main pump, so it has to keep up with your pit in heavy rain. It is there for the hours when the main pump cannot work, not to replace it.
What affects the cost of a battery backup?
The price depends on the backup pump, its capacity, and the type and size of battery. It also depends on whether the backup fits in your existing pit and whether an alarm or monitoring is added.
The discharge piping matters too. Some backups need their own outlet, and some can share your existing line. The manufacturer's instructions also set which check valves (one-way valves that stop water running back into the pit) are needed.
A plumber can look at your pit and discharge line and tell you what fits before any work starts. If your main pump is getting old, you can replace it and add the backup in the same visit.
How do you look after a battery backup?
Test the backup two to five times a year, following its manual. The right test depends on the model and how it was installed. Between tests, check that the charger shows the battery is charging and that the alarm still works.
The battery needs its own care. Some need their water level checked and terminals cleaned, while sealed batteries do not. All batteries wear out, so replace yours on the schedule in the manual, before it fails in a storm.
For the main pump, see our guides on how to test a sump pump and sump pump maintenance.
Getting a battery backup installed
We install battery backups across Burlington, Oakville, Hamilton and the surrounding area. We check your pit, main pump and discharge line and recommend a backup that fits. We explain the work and the price before we start, and test both pumps when we finish. See what is included on our sump pump services page.
If your main pump has already stopped and water is rising, call our 24/7 emergency plumbing team: Burlington 905-332-8222, Oakville 905-842-6222, Hamilton 905-545-4222.
