The Right Sump Pump
Get the Right Sump Pump
Measure for what your need
There’s no way to know which is the right sump pump unless you answer a few questions.
1. How fast does the water come in?
Go down to your sump pit on a rainy day and measure how far the water rises in one minute. An easy way to do this is to start a timer as soon as your sump pump stops running and mark the distance the water rises in 1 minute. Force the pump on again to lower the water to the shutoff level again, then measure from your mark down to the water (otherwise your tape measure will get wet).
Measure the width of the sump pit. Average sump pits are 18 inches in diameter. An inch of water in an 18″ sump pit is about 1 gallon. An inch of water in a 24 inch sump pit is about 2 gallons. Multiply inches by gallons per inch. For example if water rises 10 inches in one minute and the diameter of the sump pit is 24 inches (gallons per inch=2), then the water is rising at a rate of about 20 gallons per minute.
Sump pumps will usually list pumping power in gallons per hour (GPH), so multiply your gallons per minute by 60. Using the example measurement above, the GPH would be 1200 (60×20). This will give you a good estimate of how much water is coming in, but it will flow even faster during the worst conditions. Give yourself some leeway: take the GPH you calculate and multiply by 1.5. So for our example we would want to look for a sump pump that can pump 1800 GPH.
2. How hard will the pump need to work?
Measure the vertical distance the water is pumped. Measure the distance from the pump to where the discharge pipe turns horizontal. This is called the vertical lift or static head. Sump pumps will list GPH at various lift distances. The longer the distance, the harder the pump will have to work, and the fewer gallons per hour will be pumped. If your discharge pipe system has extra angles and turns, this will further reduce the pump’s efficiency, so tack on extra feet to the total. Just to be safe, call a licensed plumber, they will be able to calculate the exact total dynamic head for your sump pump system.
Knowing how fast water is coming into your sump pump also lets you know just how long it will take for your basement to be flooded if your sump pump fails. For instance, if you measure the water level in your sump pit rising five inches in one minute and your sump pit is 30 inches deep, your basement will start flooding 6 minutes after your sump pump fails.