Here is the problem with a basement that depends on a sump pump: the storm that fills the pit is the same storm that takes out the power. Every summer we pump out basements in Shelby Township, Macomb, Rochester Hills and Troy where the primary pump was fine, the pit was fine, and the power was off for three hours. If your pump runs during storms and your power goes out during storms, you need a backup. The rest of this article is about which kind.
Who can skip a backup
Be honest about these three questions:
- Does your pump run during or right after heavy rain? If it only runs a few times a year in spring, your exposure is low.
- Does your basement have anything in it you would be upset to lose? Finished rooms, furnace, water heater, storage.
- Does your power go out in storms? In most of our service area the answer is yes, and outages can last hours.
If you answered no, no and no, a backup is a nice-to-have. Anyone else should have one.
Option 1: battery backup pump
A second pump sits in the same pit above the primary, wired to a controller and a deep-cycle battery. When the primary stops (power loss, failure or just cannot keep up), the water rises a few inches, hits the backup float, and the backup runs on the battery. Most also sound an alarm so you know something happened.
- Run time: a good AGM battery gives you several hours of intermittent pumping, more with a second battery. That covers the typical Michigan storm outage. It will not cover a three-day outage; for that you need a generator.
- Capacity: less than the primary. A backup is there to hold the line, not to replace a half-horsepower pump in a heavy-flow pit.
- Maintenance: batteries last about 3 to 5 years. The controller tells you when it needs replacing. Test it twice a year by unplugging the primary.
- Cost: approximately $1,500 installed as an add-on to a sump system, more for a dual-battery or a higher-capacity unit.
Option 2: water-powered backup pump
Uses your city water pressure to create suction and pull water out of the pit, no electricity and no battery. For every gallon or so of city water it uses, it moves roughly two gallons out of the pit (ratios vary by model and pressure).
- Runs as long as the water main has pressure, which in a long outage beats any battery.
- Needs municipal water. If you are on a well, your well pump is also off in an outage, so this does not work for you.
- Needs a backflow preventer on the supply, and most cities in our area require a permit for that.
- Uses water you pay for, and in a very heavy flow it can struggle. Lower capacity than battery units.
- Cost: similar range to a battery backup once the plumbing is done.
Option 3: a second full pump (dual sump system)
For homes with heavy groundwater, we sometimes install a second basin and pump instead of, or in addition to, a backup. Two primaries share the load, so one failing does not flood the basement, and either can be paired with a battery. This Michigan home had more water than one pit could handle:
Option 4: a generator
A standby generator with an automatic transfer switch solves the outage problem for the whole house and runs the primary pump as long as there is gas. It does not help if the primary pump itself fails, so most homes with a generator still get a backup pump. A portable generator only helps if someone is home to start it.
What we install and why
For most homes in Macomb, Oakland and Wayne County we recommend a properly sized primary pump in a sealed basin, a battery backup pump with an alarm, and a check valve on each discharge. If the home is on city water and the owner wants outage protection measured in days, a water-powered unit instead of, or alongside, the battery. If the pit sees heavy flow, a dual system. And on every install: the discharge run far enough from the house that the water does not come straight back in, and buried below frost depth where the grade allows.
One thing a backup does not fix: a pit with no drain tile feeding it. If water comes through your floor and walls in places the pit cannot reach, the pump is only catching part of it. That is an interior drainage conversation, and we will tell you if that is what you need.
Cost summary
Approximately: standard sump system $2,500 to $3,000; battery or water-powered backup about $1,500 extra each; pump swap only, about $600; buried discharge line $1,500 to $6,500 depending on length. Full numbers in the sump pump cost guide. Note that our 25-year transferable limited warranty covers our waterproofing work, not the sump pit or the pump; pumps carry the manufacturer’s warranty.
Frequently asked questions
How long does a battery backup sump pump run?
Several hours of intermittent pumping on one battery, depending on how often the float calls for it. Add a second battery or a generator for longer outages.
Is a water-powered backup better than a battery backup?
It runs indefinitely on city water pressure, which is better for long outages, but it needs municipal water, a permit, and has lower capacity. On a well, battery is the only option.
Can I add a battery backup to my existing sump pump?
Usually yes, if the pit is large enough for a second pump. Small or shallow pits sometimes need a new basin.
Do I need a sump pump at all in Michigan?
If your home has drain tile around the footing, it needs somewhere to go, so yes. Homes without any pit are usually relying on gravity to a storm sewer or on luck; we can tell you which with an inspection.
How often should I test the backup?
Twice a year: unplug the primary, pour water in the pit, and confirm the backup runs and the alarm sounds. Replace the battery every 3 to 5 years.
Mansour’s Innovations is a family-owned waterproofing, excavation and plumbing contractor in Shelby Township, Michigan, serving Macomb, Oakland and Wayne counties since 2014. Owner Imad “Matt” Mansour has 20+ years in the trade and the crew has completed 1,600+ projects. Our waterproofing work carries a 25-year transferable limited warranty. Call or text (586) 345-7292 for a free estimate.