How To Install a Sump Pump
Flooding can ruin your basement and everything in it, but there's a solution. Learn how to install a sump pump and keep your basement dry.
A sump pump keeps basements dry. It’s absolutely essential if your basement floor pad was poured close to the natural water table.
Installing one is pretty simple, but requires some forethought. First, know the different types of sump pumps: submersible, pedestal, battery-operated and water-powered.
Submersible sump pumps are generally the most expensive, but also the most robust and reliable in my experience. I’ve seen them work for decades without failing. Here, we’ll focus on installation techniques for submersible sump pumps.
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Tools and Materials To Install a Sump Pump
- Rotary hammer with long 3-in.-dia. and 1-in. bits;
- Hand saw;
- Safety glasses;
- Hearing protection;
- Permanent felt-tip pen;
- Several five-gallon buckets;
- One 120-volt submersible sump pump with float switch (1/2-horsepower for moderately wet areas, 3/4-hp for spots with heavy flooding);
- Battery-powered backup sump pump with float switch (1/2-hp for moderately wet areas, 3/4-hp for spots with heavy flooding);
- Plastic sump tank (18-in.-dia. by 24-in. deep is standard);
- Multiple lengths of 2-in. PVC pipe with 90-degree elbows and straight couplers;
- Can of spray foam;
- Quick-set concrete (mortar);
- PVC cement;
- 3/4-in. gravel.
Choose Your Location and Pumps
- Scope out the land around your house. Find an area where the land slopes naturally downward and away from your home, but not directly into a neighboring yard. Note which wall of your house borders the low area.
- In your basement, locate the wall closest to the low spot outside.
- Place your plastic sump tank on the basement floor in a spot close to a GFCI electrical outlet, roughly six inches from the wall where it’s convenient to drill a hole.
- With a permanent felt-tip pen, trace a circle on the basement floor around your sump tank.
- Move the sump tank to one side and make a second mark on the floor six inches larger in diameter than the circle you just traced. Elongate this second mark on the wall side so it butts up against the wall, forming a long oval shape with one end cut off.
Dig Out the Sump Hole
- With your rotary hammer, drill a series of 1-in.-dia. holes through your basement floor foundation slab, following the larger of your two lines. Be sure to use eye and hearing protection.
- Continue drilling through the floor slab until you’ve replaced your entire line with side-by-side holes.
- Take a sledgehammer and break the concrete within your border of holes into pieces. Remove these pieces carefully and dispose of them at a landfill or recycling station.
- Once all the concrete is out of the hole, you should see soil. Dig this out there’s a hole large and deep enough to fit your sump tank, with six inches extra on the bottom and sides.
Install the Sump Tank
- Line the bottom of your hole with about six inches of 3/4-in. gravel.
- Place your sump tank into the hole. The top of the tank should be flush with or just above the surface of the surrounding floor.
- Fill in the space around the tank with more gravel until the hole is nearly full. Leave an inch or two of empty space at the top for mortar.
- Mix a small batch of quick-set concrete, then carefully trowel it over the graveled area around the sump tank. Try to make it a smooth continuation of the surrounding floor slab.
- Allow the concrete to fully harden.
Install the Discharge Pipes
- Outside, take your rotary hammer and drill a 3-in.-dia. hole through your basement wall as close as possible to the sump pump tank, one to two inches above ground level. This hole will be for the discharge line of your main sump pump. Be sure to use eye and hearing protection.
- Drill a second identical hole about one foot to the left or right of the first one, whichever direction places it closest to your sump inside. This will be for the discharge line of your backup sump pump.
- Thread a length of 2-in. PVC pipe through each hole in the wall. Use coupler and elbow fittings as needed to extend the pipes to the low spot you identified earlier.
- Make sure both pipes protrude several inches from your basement wall.
Install the Main Pump and Backup Pump
- Place your main sump pump and battery-operated backup pump into the bottom of the sump tank. Because your battery-powered pump is smaller, it should fit in the sump tank alongside the main one.
- Position your battery-powered pump so the float switch that activates it is several inches higher than the float switch of the main pump. You only want the battery-powered pump to kick on if the main pump fails.
- Use PVC cement to join 2-in. PVC elbow fittings to short lengths of PVC pipe. Cut these with a handsaw as needed to connect to your pumps and branch out of the sump tank through the factory-made holes in the lid.
- Add more lengths of pipe and fittings as needed, bonded together with PVC cement, to extend these pipes over to the wall where you drilled holes.
- Use 90-degree elbows and PVC cement to join the two pipes going up the wall to the pipes coming through the holes you drilled. Cut them to length first, as needed.
- Pour water into your sump if water hasn’t collected there naturally already. Plug in your pumps one at a time to test them. With the battery-operated backup pump, you’re plugging in the charger.
- Allow the pumps to clear the water from your sump. Then plug them both in, with the battery and charger working to continuously charge your backup pump.
Seal the Holes
- Finish up by injecting spray foam into the holes in your basement wall around the discharge pipes.
- Allow the foam to fully harden.