How to Install a Sump Pump
Updated February 20, 2026
Install or replace a sump pump for reliable basement flood protection -- pump selection, pit prep, check valve, discharge line routing, and the testing routine that keeps it working.
Overview
Your sump pump is the thing standing between a dry basement and a flooded one. It sits in a pit that collects groundwater and pumps it out when the level rises. Replacing a failed pump is straightforward -- swap the unit in an existing pit with an existing discharge line. Installing from scratch (pit, pump, discharge) is bigger but doable for a confident DIYer. Two critical decisions: the right pump (submersible vs pedestal, HP, switch type) and routing the discharge so water goes away from your foundation instead of seeping right back.
What You'll Need
Safety First
- The pump must plug into a GFCI-protected outlet. No GFCI near the pit? Have an electrician install one before you start. Never run a sump pump on a non-GFCI circuit in a wet environment.
- No extension cords. They reduce voltage over distance, overheat the motor, and cause premature failure. The pump plugs directly into a dedicated outlet within 6 feet of the pit.
- Cutting into the basement floor for a new pit? Check for underground utilities first -- water lines, sewer, electrical conduit, radon pipes. Call your utility company for a locate if you are not sure what is down there.
- Flooded or wet basement? Do not stand in water while plugging or unplugging anything. Rubber-soled boots and a dry board to stand on near the electrical connection.
Step-by-Step Instructions
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Choose the Right Sump Pump
Submersible pumps sit in the pit, submerged. Quieter, more powerful, longer-lasting -- the standard choice for most homes. Pedestal pumps mount the motor above the pit with just the impeller in the water. Cheaper and easier to service but louder and weaker. Sizing: 1/3 HP submersible handles most homes (up to about 2,500 GPH). High water table or heavy pumping? Go 1/2 HP. Float switch matters too: vertical float is most reliable for standard pits, tethered float for wider pits, electronic switch is the most reliable overall but costs more.
Tip: Get a pump with a cast iron or stainless steel housing, not plastic. Metal dissipates motor heat into the surrounding water, extending the pump's life. Plastic traps heat and the motor runs hotter. The price difference is only $30-50. -
Prepare or Inspect the Sump Pit
Replacing? Unplug the old pump, disconnect the discharge pipe, lift it out. Clean debris, gravel, and sediment from the pit. The pit needs to be at least 18 inches across and 24 inches deep for a submersible. New installation? You are breaking through the basement floor with a jackhammer, digging the pit, lining it with a sump pit liner ($20-40 perforated plastic barrel), and putting 2-3 inches of gravel in the bottom. The gravel keeps sediment from clogging the intake. The liner should sit slightly above floor level so debris does not fall in.
Tip: Have a French drain (perforated pipe around the interior perimeter)? The sump pit goes at the lowest point where the drain pipes converge. The French drain channels groundwater to the pit, the pump removes it. Adding a pit to an existing system? Connect the drain pipe to the pit liner. -
Install the Check Valve on the Discharge Pipe
The check valve stops pumped water from flowing back into the pit when the pump shuts off. Without it, the water in the discharge pipe drains right back down, the pump kicks on again immediately (short cycling), and the motor burns out years early. Install the check valve on the vertical discharge pipe, 6-12 inches above the pit. Use a PVC check valve with rubber coupling connections (no glue, hose clamps for easy future removal). Arrow on the valve points up -- direction of flow.
Warning: The check valve is the most important piece in the entire installation. Missing or failed check valve means the pump short cycles constantly. That kills a motor in 1-3 years instead of the expected 7-10. -
Route the Discharge Line
The discharge line carries water from the pit to outside. Use 1-1/2 inch PVC (matching the pump outlet). Route from the check valve up through the basement wall (drill through the rim joist or foundation with a hole saw). Outside, the line needs to extend at least 10 feet from the foundation and drain onto a downward slope away from the house. Do not drain into a storm sewer (illegal in many areas), onto a neighbor's property, or onto a sidewalk where it ices over in winter. A grassy slope away from the foundation is ideal.
Tip: Cold climate? The exterior discharge line can freeze and block flow, causing the pump to run nonstop or the pit to overflow. Install a freeze guard (pop-off fitting near the foundation that lets water escape if the line freezes) or bury the line below the frost line to a dry well. -
Set the Pump, Connect, and Test
Lower the pump into the pit -- level on the gravel, not sitting on debris that could clog the intake. Connect to the discharge pipe. Plug into the GFCI outlet. Fill the pit with a garden hose or buckets. The float switch should kick the pump on when water hits the preset level (usually 6-8 inches above intake). Pump runs, water discharges, float drops, pump shuts off. Test this cycle 3-4 times. Verify the discharge flows freely outside. Check all connections for leaks. Put the pit cover on to keep objects out and reduce noise.
Tip: Label the GFCI outlet: 'SUMP PUMP -- DO NOT UNPLUG.' Set a calendar reminder to test the pump every 3 months -- pour a bucket of water in and verify it kicks on and pumps out.
Pro Tips
- Install a battery backup pump as a secondary system ($150-300). Primary pumps fail during power outages -- exactly when heavy rain makes flooding most likely. A backup activates automatically and provides 4-12 hours of pumping on a charged battery.
- A sump pump alarm ($15-25) sits at the top of the pit and screams if water rises too high. Alerts you to pump failure before the pit overflows. One of the cheapest and most effective flood prevention devices you can buy.
- Replace the pump proactively every 7-10 years, even if it still works. Sump pump failure happens without warning -- usually during a heavy rain when you need it most. Scheduled replacement prevents emergency failures.
- Pump running constantly during dry weather? Check the discharge line distance. Water dumped too close to the foundation seeps back through the soil to the pit, creating an endless cycle. Extend the discharge at least 10 feet out.
- Wi-Fi sump pump monitors ($30-100) send alerts to your phone when the pump activates, water is high, or the pump fails. Real peace of mind when you are away during storms.
When to Call a Pro
Call a plumber or waterproofing contractor if you need a new pit cut in the floor (jackhammer and concrete work), if you are connecting to a French drain system, if you need a GFCI outlet installed (electrician), if the discharge line needs burying or connecting to a storm drain (may need permits), or if your flooding is severe enough for a commercial-grade system.