Backup sump pumps in Fargo-Moorhead homes
In much of Fargo, Moorhead and West Fargo, the sump pump is one of the hardest-working machines in the house. Drain tile around the foundation collects groundwater, sends it to the sump pit, and the pump pushes it outside. When that pump stops, whether from a power outage during a spring storm or a float switch that sticks, water can rise into the basement quickly. A backup sump pump is a second line of defense that takes over when the main pump can’t.
This guide explains why a backup sump pump matters here, how battery and water-powered backups compare, what it means when an inspection finds no backup, and how to keep one ready to work.
Why a backup sump pump matters in the Red River Valley
The Red River Valley sits on dense lake clay that drains slowly. After snowmelt or a heavy rain, groundwater can keep flowing into the drain tile for days, and the sump pump may cycle every few minutes. For more on how these soils behave, see Why Foundations Move in Fargo-Moorhead.
Two things make a backup worth having:
- Storms bring outages. The times a sump pump works hardest, like spring storms and heavy summer rain, are also the times the power is most likely to go out.
- Pumps wear out. NDSU Extension lists worn or rusted motor bearings and float switches with poor electrical contact among the most common reasons sump pumps fail. A pump that sat idle all winter can fail on the first busy day of spring.
A finished basement makes the stakes higher. Carpet, drywall and stored belongings can be damaged by just a few inches of water.
Signs your sump system needs attention
- There is no backup pump in the pit
- The home has a second (overflow) sump pit with no pump in it
- The pump runs very often, or cycles on and off in quick bursts
- The pump is rusted, or sounds “like it is pumping gravel,” a warning sign NDSU Extension mentions
- The discharge pipe is disconnected, leaking, or blocked by ice
- Water stains or white mineral deposits on the floor near the pit
- A battery backup whose charger shows a warning light, or a battery with corroded terminals
Battery vs. water-powered backup sump pumps
There are two common types of backup sump pump. Both sit in or next to the sump pit and turn on only when the water rises above the level where the main pump should have started.
Battery backup pumps run on a 12-volt deep-cycle battery that a dedicated charger keeps topped up. NDSU Extension engineers tested one and found that run time depends on battery size and how often water comes in. With the pump running nonstop, a 40 amp-hour battery lasted less than four hours, and a 120 amp-hour battery was estimated at about 11 hours. When the pump only had to run every four minutes, a 75 amp-hour battery lasted at least 60 hours. NDSU recommends buying the largest amp-hour rating the pump manufacturer allows. If the main pump fails while the power is still on, the charger keeps the battery up and the backup can run for days.
Water-powered backup pumps use city water pressure instead of electricity. Water flowing through the pump creates suction that pulls water out of the pit. They need no battery, but they do use water while they run. One manufacturer, Basepump, lists a working range of 40 to 90 psi and says its pumps remove about 2 gallons of sump water for every gallon of city water used at 90 psi. Because the pump connects to your drinking water line, it must have a backflow prevention device, and some of those devices need yearly testing. Homes on a private well usually can’t rely on a water-powered backup, because the well pump needs electricity too.
| Battery backup | Water-powered backup | |
|---|---|---|
| Power source | 12-volt deep-cycle battery | City water pressure |
| Works in a power outage | Yes, until the battery runs down | Yes, as long as city water pressure holds |
| Main limit | Battery size and age | Water pressure, water use, backflow rules |
| Upkeep | Test the battery every six months; replace it as it ages | Test the pump; keep the backflow device tested as required |
| Best fit | Most homes, including homes on a well | Homes on city water with good pressure |
Check local plumbing rules before installing either type, especially a water-powered pump, and have a licensed plumber do the work if you are not comfortable with it.
What “no backup sump pump” means in an inspection report
When we find a sump pump with no backup during an inspection, we note it and recommend considering a battery or water-powered backup. This is not a defect in the main pump. It is a recommendation to lower the risk of a wet basement if the main pump fails or the power goes out.
Some homes have two sump pits: a primary pit that receives water from the drain tile, and an overflow pit that receives water if the primary pump fails. When the overflow pit has no pump, we recommend installing a backup pump there, powered by a battery or water pressure.
We also look at the rest of the system: whether the main pump runs (when the pit depth allows testing), how the discharge pipe is connected, and where the water goes once it leaves the house. If you are buying a home, our home buyer’s inspection covers the sump system along with the rest of the basement.
How to keep a backup sump pump ready
- Test both pumps a few times a year, and always before spring thaw. NDSU Extension suggests pouring water into the pit until the pump turns on and off at least twice. To test the backup, unplug the main pump briefly so the backup has to do the work, then plug the main pump back in.
- Check the battery every six months. NDSU says a resting battery should read about 12.3 to more than 13 volts. While the backup pump runs, a reading above 12.1 volts is acceptable; below 11.6 volts, it is time for a new battery.
- Keep the charger dry and reachable. NDSU recommends mounting it 3 to 4 feet above the basement floor near the sump.
- Keep the pit clean and covered so debris can’t jam the float switches.
- Plan for winter discharge. A frozen discharge line can stop even a healthy pump. See how to discharge your sump pump in winter.
- Think about a longer outage. NDSU notes that a 1,500-watt generator can run a typical main sump pump and the battery charger if someone is home to operate it.
Lars also talked about backup pumps on KFGO; you can listen to that segment in Backup Sump Pumps in Your Basement.
Backup sump pumps: common questions
Do I need a backup sump pump if my pump rarely runs? Many sump pits sit dry for months and then run hard during spring melt or a wet stretch. A backup is for exactly those times, when a failure would do the most damage.
Can the backup go in the same pit as the main pump? Yes. NDSU Extension notes that many homes add a battery backup in the same sump. It is set to turn on at a slightly higher water level than the main pump.
How long will a battery backup run? It depends on the battery and how fast water comes in. In NDSU’s tests, run times ranged from a few hours of nonstop pumping to several days of occasional pumping.
Will a water-powered backup work on a private well? Usually not. During a power outage the well pump stops, so there is no water pressure to run the backup.
Does homeowners insurance cover a flooded basement from a failed sump pump? Often only with an added water backup endorsement. Check your policy and ask your agent.
Sources
- Scherer, Tom, and Ken Hellevang. Pumps for Houses: Sump Electric Backup (AE1771). NDSU Extension, reviewed March 2021.
- NDSU Extension. Now Is the Time to Check Your Sump Pump. March 17, 2022.
- Basepump. Water-powered backup sump pump product brochure.