Almost every house has one. It’s generally located in a damp, dark hole in the floor, and most homeowners pay it no attention until they are standing ankle deep in water during a storm. Yup, it’s your sump pump.
Think of your basement as a reverse swimming pool. Instead of a hole in the ground keeping water in, you have a hole in the ground trying to keep water out. I say trying because most basement structures fail at keeping rainwater and ground water out. The soil around your foundation is very porous and holds water like a sponge during wet times. If your basement is 8’ in the ground, then the wet soil is like having a column of water 8’ high pushing against your foundation wall at your footers. That column of water is equal to 3.5 pounds per square inch (psi). That may not seem like a lot of pressure, but try blowing 3.5 psi on a gauge! A grown man can blow a pressure of about 1.4 psi. So, when it rains, there is a very real chance of water getting into your basement. Various construction methods help direct this rainwater to your sump which is where the sump pump comes in play. A good 1/3 horsepower sump pump will discharge about 44 gallons per minute (gpm) at 10’ of head. What’s that mean?! It means the pump will pump 44 gpm through a vertical pipe 10’ high, which is about the maximum vertical lift for a pump in a buried sump in a basement 8’ in the ground. So, is 44 gpm good? Let’s do some math: Let’s just say you live on an acre of ground. That’s 43,560 ft². And let’s say we get one of those kick a** thunder storms that spring up in the summer (we wouldn’t know anything about this year would we…). This storm dumps an inch of rain in about an hour; a lot of rain to be sure, but not an unreasonable amount for a summer storm. An inch of rain on an acre of ground is 3,630 ft³ of water, and a ft³ of water is equal to 7½ gallons. Your acre of paradise just had 27,225 gallons of water dumped on it! Now, not all of that water is going to be directed to your house and into your basement. Not if your builder did his job in grading and installing rain leaders. But, some of this water makes its way to your house. Let’s say 5% of that 1” of rain is going to get to your foundation and seep in through the foundation. By the way, I have no idea exactly how much will get to your basement, this is a HYPOTHETICAL example. Five percent of 27,225 is about 1,361gallons of water. Now, let’s go back to our sump pump that can pump 44 gpm. That equals 2,640 gallons per hour. That is about double the 1,361 gallons we are assuming is going to get through your foundation wall. So a GOOD 1/3 hp sump pump should be sufficient. We use the Myers MCI033 at Apple Plumbing. It is a nice, solid, cast iron pump with a float rod switch (less likely to hang up in the sump). Other good pumps are Goulds and Zoeller.
You should check your sump pump once a year, or have us check it out. We do this by pouring water in the sump until the pump comes on and observe the rate of discharge. Is it a strong, steady stream or a weak one? Make sure the pump is sitting on a solid base and there is no debris, silt, mud or stone in the sump that could clog up the pump.
That was quite a lot of information, but it really is too late to find out your pump doesn’t work when your basement is flooded!
Stay tuned for next week’s post on back up pumps!
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