What You Need to Do Before You Start

Installing a sump pump yourself is possible if you already have a sump pit dug and you are comfortable working with electrical connections and plumbing. Most installations take four to six hours. You will need to shut off power to the area where you are working, dig or prepare the pit if one does not exist, run discharge piping to the outside of your home, and make electrical connections — all of which carry real risks if done wrong. If your basement floods regularly or you are unsure about any step, hiring a plumber or basement contractor is safer and often costs less than fixing a failed installation.

Before you buy anything, check your local building codes. Some areas require a permit for sump pump installation, and many have rules about where discharge water can go. Your city or county building department can tell you what applies to your address. If a permit is required and you skip it, you may face fines or be forced to remove the pump.

Key Takeaways

  • A sump pit must be at least 18 inches deep and wide enough for the pump to sit level; if you do not have one, you will need to dig it or hire someone to do so.
  • Discharge piping must run uphill and away from your foundation — typically 4 to 10 feet out — and should have a check valve installed on the pump outlet to prevent backflow.
  • The pump sits in the pit on a solid base, with the intake screen submerged and the outlet pipe connected before you fill the pit with water.
  • Electrical connections must be made to a dedicated outlet or hardwired by a licensed electrician; plugging a sump pump into an extension cord or shared outlet creates a fire and shock hazard.
  • Test the pump by pouring water into the pit until it triggers the float switch, then watch it run through a full cycle before you leave it unattended.

Preparing the Sump Pit

The pit is the foundation of the whole system. It needs to be at least 18 inches deep and wide enough for the pump to sit level without tilting. If you do not have a pit, you will need to dig one in the lowest corner of your basement or crawl space — the spot where water naturally collects. The pit should be below the floor level so water flows into it by gravity rather than requiring a separate pump to move it there.

Once the pit is dug, line the bottom with 3 to 4 inches of gravel. This creates a base that keeps the pump from sitting directly on soil and allows water to flow underneath it. The gravel also prevents sediment from clogging the pump intake. If the pit walls are bare soil, consider installing a plastic pit liner to prevent the walls from collapsing and to keep sediment out of the water.

Check that the pit bottom is level. A pump sitting on a tilt will wear unevenly and may not trigger the float switch correctly. Use a level to confirm before you place the pump.

Running Discharge Piping Outside

The discharge pipe carries water from the pump to the outside of your home. It must run uphill and away from your foundation — typically 4 to 10 feet out — so water does not flow back toward the basement or pool around the foundation. The pipe should exit through the basement wall or floor, or through a window well, depending on your home's layout.

Use 1.5-inch PVC pipe for most residential pumps. Drill or cut a hole through the foundation wall large enough for the pipe to fit through with a slight slope upward toward the outside. The slope should be at least 1/4 inch per foot of run — meaning for every 4 feet of horizontal pipe, the outlet end should be 1 inch higher than the inlet. This prevents water from sitting in the pipe and freezing in winter.

Install a check valve on the pump outlet before the pipe leaves the basement. The check valve allows water to flow out but prevents it from flowing back into the pit when the pump is off. Without it, water will drain back into the pit and the pump will cycle constantly. Connect the discharge pipe to the check valve outlet, then run it to the outside. At the exterior end, install a discharge line extension — a short piece of pipe that directs water away from the foundation and sits above ground so you can see the pump working. The extension should point downward at a slight angle so debris does not collect in the opening.

Installing the Pump in the Pit

Place the pump on the gravel base in the center of the pit. The pump should sit level and stable. Most submersible pumps come with a mounting bracket or base that keeps them from tipping. If yours does, use it.

Connect the discharge pipe to the pump outlet. Hand-tighten the connection first, then use a wrench to snug it — do not over-tighten, as this can crack the fitting. The intake screen on the bottom of the pump should be fully submerged once water enters the pit, so make sure the pump sits low enough in the pit for this to happen.

Do not fill the pit with water yet. Wait until the electrical connection is complete and tested.

Making the Electrical Connection

This is the step where mistakes cause fires and electrocution. If you are not confident working with electrical wiring, hire a licensed electrician.

The pump must connect to a dedicated outlet — one that serves only the sump pump, not a shared circuit with other appliances. The outlet should be a GFCI (ground fault circuit interrupter) type, which cuts power when ready if it detects a short or ground fault. Most building codes require this. The outlet should be located above the basement floor level so it does not sit in standing water if the pit overflows.

If the pump comes with a plug, plug it into the GFCI outlet. If it is hardwired (no plug), the wires must be connected to the outlet by a licensed electrician using proper wire gauges and connectors. Never use an extension cord or power strip for a sump pump — these are fire hazards. If the outlet is too far away, have an electrician run a new circuit to a location closer to the pump.

Once the electrical connection is made, do not turn the pump on yet.

Testing Before You Leave It Running

Pour water into the pit slowly until it reaches the level where the float switch should trigger. Watch the pump turn on. Let it run until the water level drops below the switch and the pump shuts off. This is one complete cycle. Run the cycle two or three times and listen for any unusual noises — grinding, squealing, or rattling means something is wrong and you should turn it off and check the connections.

Check the discharge pipe outside. Water should flow out steadily and not back up into the pit. If water is not flowing, the check valve may be stuck or the discharge line may be blocked.

Once the pump runs smoothly through several cycles, you can leave it running. Most pumps have a float switch that turns them on and off automatically as the water level rises and falls. Some have a manual on/off switch as well — leave it in the on position so the pump responds to the float.

Maintenance and Troubleshooting

Check the pump once a month by pouring water into the pit and confirming it turns on and shuts off. If the pump runs constantly or does not turn on at all, the float switch may be stuck or the intake screen may be clogged with sediment. Turn off the power and inspect the screen. Clean it with a brush or replace it if it is damaged.

In winter, check the discharge line regularly to make sure it is not frozen. If it is, pour warm water down the line from inside the basement to thaw it. Some people install a discharge line extension that sits above ground in a way that prevents ice buildup, or they use a heated discharge line.

If the pump is more than five years old and starts running more often than it used to, the impeller may be wearing out. Most pumps last seven to ten years before they need replacement.

Frequently Asked Questions

Can I install a sump pump in a basement that does not have a pit?

No, you need a pit for the pump to sit in. If you do not have one, you will need to dig one or hire a contractor to dig it. The pit must be at least 18 inches deep and positioned in the lowest corner of the basement so water flows into it naturally.

What size pump do I need?

Pump size depends on how much water your basement collects. A 1/3 horsepower pump handles most residential basements. If water rises quickly or you have a large basement, a 1/2 horsepower pump is safer. Your plumber or pump supplier can recommend the right size based on your pit size and water volume.

Do I need a backup pump?

A backup pump is not required but is a good idea if your basement floods often or if you have valuable items stored there. Battery-powered backup pumps turn on automatically if the main pump fails or power goes out. They cost $300 to $600 and can prevent thousands of dollars in water damage.

What should I do if the pump keeps running?

A pump that runs constantly usually means water is entering the pit faster than the pump can remove it, or the float switch is stuck. Check that the discharge line is not frozen or blocked. If the line is clear and water is still rising, the pump may be too small for your water volume and you may need a larger one.

Can I bury the discharge pipe underground?

No. Discharge pipes must run above ground so you can see water flowing out and so the line does not freeze or clog underground. The pipe should exit the foundation and extend 4 to 10 feet away, then sit above ground with a slight downward angle at the end.