Most homes use a 1/3 horsepower sump pump, but the right size depends on how fast water flows into your sump pit and how high the pump has to lift it. The one-minute test below shows you how to measure your home’s inflow and choose a pump that can keep up.
Like much of the plumbing and machinery in your home, you may not think about your sump pump most of the year. However, when there is a heavy rainfall or snow melt here in Montana, the sump pump in your home becomes vital to ensure you will not be standing in ankle-deep water, or up to your neck in water damage repair bills. But how do you know which sump pump is right for your home, and which size sump pump you need? Learn more about sump pumps here, including what they are and what size sump pump you will need in your home.
What Is A Sump Pump?
The sump pump in your home is a submersible device installed in the lowest part of your home, usually in the basement or crawl space. It may be small, but it is an important part of your home that keeps the basement from flooding.
Most of the time, especially during warm, sunny weather, the pump is not working, simply on standby until it is needed. However, when it rains heavily or snow close to the home begins to melt, the soil around the base of your home will become oversaturated with water. This excessive groundwater funnels toward the sump pump in the low pit it sits in. This activates the pump, which begins to pump water out of the home. Excess water is then funneled into a nearby storm drain, dry well or pond. This prevents the water from rising in your home!
Never connect a sump pump to the sanitary sewer. The City of Kalispell’s sewer service rules prohibit connecting sump pumps, foundation drains and roof downspouts to any drain or sewer line that leads to the city sanitary sewer.
How To Tell If You Need A Sump Pump
Where you live says a lot about whether you will need a sump pump in your home. Some properties will need these devices more than others. Here are some scenarios where you will need a sump pump:
- You live in a place that receives heavy rain or snow (yes, that is us here in Montana!)
- Your home is built in a flood-prone area
- You have had flooding or water problems in the past
- Your basement is finished
Why Does Your Sump Pump Need To Be The Right Size?
Isn’t there a saying that “bigger is better?” With sump pumps, this is not always the case. An oversized sump pump can lead to constant cycling, which will cause your system to burnout prematurely. An undersized pump can lead to the same issue or may not be able to handle the water in your home. It is important to choose a sump pump that is the right size for your home and sump pit.
What Size Sump Pump Do I Need For My Home?
There are several factors you will need to take into consideration when choosing the size of your sump pump, including capacity, motor power and the size of your sump pit, or the hole where the sump pump sits.
Capacity:
Your sump pump needs to remove water faster than it flows into the pit. Measure the inflow on a rainy day or during snowmelt:
- Let the pump run until the water drops to the shutoff level.
- Unplug the pump for one minute. Do not leave it off any longer than one minute.
- Measure how many inches the water rises.
- Convert inches to gallons. A round pit 18 inches across holds about 1.1 gallons per inch of depth. A 24-inch pit holds about 2 gallons per inch.
- Multiply by 60 to get gallons per hour.
- Multiply that by 1.5 for a safety margin during heavy rain and spring snowmelt.
Plug the pump back in when you finish. Choose a pump rated to move at least that many gallons per hour at your lift height.
Motor Power:
The horsepower of the motor states how powerful the sump pump’s motor is. Sump pumps are generally standard at .33 horsepower, but they can also be .25 horsepower, .5 horsepower (1/2 horsepower) or even ¾ horsepower. If your home sits in a high water table or the pump runs often, you may want a 1/2 horsepower motor or larger. Horsepower alone doesn’t tell you how much water a pump moves. Flow drops as the lift increases, so check the manufacturer’s performance chart for the gallons per hour at your lift height: the vertical distance from the pump to where the discharge pipe leaves the house.
Sump Pit Size And Other Factors:
If your sump pit size is wider than standard, it may hold more water. Additionally, if the water must move farther through the discharge pipe, for instance, to a drain half a block away instead of right outside your home, the pump may have to take longer to push the water out.
How Long Does a Sump Pump Last?
InterNACHI’s life expectancy chart lists a typical sump pump life of about 7 years, and a pump that runs often can wear out sooner. Replacing an aging pump is safer than waiting for it to fail.
Ask your insurance agent whether your policy covers water damage from a failed sump pump or a sewer backup. The Insurance Information Institute says backup coverage is available from most insurers for a nominal cost.
Common Sump Pump Problems
- Water draining toward the foundation. Check gutters for ice, and check that no hose bibs froze over the winter.
- Power failure. A sump pump does nothing without power. An alarm or an electronic level control switch warns you of a failure. A battery backup pump keeps working during an outage. A standby generator can also power the pump when the grid goes down.
- A stuck float switch. Some types of float switches resist sticking better than others. A plumber can check that your pump has the right switch.
- An overwhelmed pump. An undersized pump cannot keep up with heavy water flow. See “Motor Power” above.
- A frozen discharge pipe. If the discharge pipe is not pitched properly, water collects in it and freezes. The water then falls back into the pit until the pit overflows onto the basement floor. Proper pitch, a freeze-proof fitting or adequate heat in that area keeps the pipe clear.
Test Your Sump Pump Each Spring
Spring is a good time to check the pump before the rains and snowmelt. Make sure the pump is plugged in, remove the lid from the pit, and pour in about a gallon of water. The pump should turn on.
Sump Pump FAQ
What size sump pump do most homes need?
Most homes use a 1/3 horsepower pump. Homes with a high water table or a pump that runs often may need 1/2 horsepower or more. The one-minute test above tells you how much water your pit takes in.
Can a sump pump be too big?
Yes. An oversized pump empties the pit too fast and cycles on and off often, which wears it out sooner.
How long does a sump pump last?
InterNACHI lists about 7 years. Test your pump every spring and replace an aging pump before it fails.
Can I drain my sump pump into the sewer?
Not into the sanitary sewer. Kalispell’s sewer rules prohibit it. A plumber can route the discharge to an approved location.
Central Heating Cooling Plumbing Electrical
If you are concerned your sump pump is the wrong size or need a new sump pump for your home, your best bet is to contact a professional plumber, who can evaluate the situation for you. Contact the team at Central Heating Cooling Plumbing Electrical here in Kalispell, Montana, for more information.
