Short answer
A battery backup sump pump sits in the same pit as the main pump and takes over when the power fails or the main pump stops. In Anderson, where the soil survey estimates a shallow water table under much of the city and storms knock out power when inflow peaks, a backup is close to essential. Plan run time for long outages, and add an alarm. Installed cost typically runs $600-$1,600.
On ground that holds water for weeks, a single sump pump is a single point of failure. A backup is how you stop one pump failure or one power outage from becoming a flooded basement.
Why backups matter more in Anderson
- Pumps work hard here. The soil survey estimates a seasonal water table within about a foot of the surface under 56% of sampled city land (USDA NRCS). In spring, the main pump may cycle constantly, which wears it out sooner.
- Storms bring outages. The August 2026 storms that pushed the White River to a record 24.93 feet at Anderson came as a week of heavy rain (National Weather Service). Storms like that bring both peak inflow and power failures.
- Pits refill fast. On saturated till, a pit can fill and overflow within hours once the pump stops.
Types of backup
| Type | How it works | Watch for |
|---|---|---|
| Battery backup pump | A second pump in the pit runs on a deep-cycle battery | Run time drops when the pump cycles often; batteries need replacing every few years |
| Combination system | Main and backup pump on one mount with a shared controller | Easier to install in a small pit |
| Water-powered backup | Uses city water pressure to move pit water | Needs good municipal water pressure; uses water while running |
| Generator | Powers the main pump in an outage | Needs fuel, a safe outdoor location and someone home to run it |
Run time: the question to ask
Rated run times assume a certain number of cycles. In an Anderson spring, the backup may cycle far more often than that. Ask the installer to time how fast your pit refills in wet weather and estimate how long the battery lasts at that rate. For long outages, a second battery or a water-powered backup adds margin.
Alarms
A high-water alarm in the pit is inexpensive and catches pump failures before water reaches the floor. Wi-Fi models text your phone, which matters if you’re away during a storm.
Costs
Adding a battery backup typically costs $600-$1,600 installed (published ranges; sources). If the existing pit is too small for two pumps, a new basin adds to the price.
Signs your current setup isn’t enough
- The main pump has run for days at a time in past springs (see spring and snowmelt leaks).
- Your power has gone out during a storm before, even briefly.
- You travel, or you’d sleep through an overflowing pit.
- The basement is finished, or the furnace, water heater and stored belongings sit on the floor.
- The pit refills within minutes during wet weeks.
If any of these fit, a backup costs little compared with one cleanup. The first-hour flooding checklist shows what that cleanup involves.
Batteries
Backup pumps run on deep-cycle batteries, not car batteries. Sealed (AGM) batteries need little care. Flooded (wet-cell) batteries cost less, but you have to check the water level. Keep either kind off the floor in a ventilated spot, and write the install date on it. A controller that tests the pump and reports battery health saves guessing.
When a backup isn’t the answer
A backup covers a stopped pump. It won’t fix a main pump that can’t keep up, a discharge that sends water back toward the house, or water that never reaches the pit. If the main pump runs nonstop, deal with that first, through replacement or a fix to the discharge line. If water appears at the walls while the pit stays low, the drainage needs work: see interior drain tile.
Questions to ask the installer
- How long will this battery run at my pit’s wet-weather refill rate?
- Do both pumps share one discharge line, and does each have a check valve?
- Does the alarm sound for high water, for a pump failure and for a low battery?
- Can I test the backup without unplugging anything?
- When will the battery need replacing, and what does that cost?
Maintenance
- Test the backup when you test the main pump: unplug the main pump and pour water into the pit.
- Check the battery’s charge indicator monthly and replace it on the maker’s schedule.
- Keep the backup’s float clear of the main pump’s cord and float.
The rest of the system is covered on sump pumps.