What You Need to Know Before You Start

Installing a sump pump yourself is possible if you already have a sump pit in your basement, but the job requires digging, electrical work, and plumbing connections. Most homeowners hire a plumber or contractor for the full installation because mistakes with the discharge line or electrical hookup can send water back into your basement or create a safety hazard. If you have a pit already dug and you are comfortable with basic plumbing and electrical tasks, you can handle the pump itself—but the pit excavation and final electrical connection should go to a licensed electrician in most states.

The entire process takes one to three days depending on whether the pit exists, how deep it needs to be, and whether you are running the discharge line inside or outside the foundation. Budget for a submersible pump (the most common type for basements) in the $300 to $800 range, plus materials for the pit, discharge pipe, and check valve.

Key Takeaways

  • A sump pit must be at least 18 inches deep and wide enough for the pump to sit flat; if you do not have one, you will need to excavate before the pump can go in.
  • The discharge line must slope downward away from your foundation and end at least 10 feet away, or connect to a municipal storm drain—water that drains back toward the house defeats the purpose.
  • A check valve installed on the discharge line prevents water from flowing backward into the pit when the pump shuts off.
  • The pump's electrical cord must be plugged into a GFCI-protected outlet (ground fault circuit interrupter), which is a safety requirement in most building codes.
  • If the pit is deeper than 4 feet or you need to run electrical wiring, hire a licensed contractor or electrician to avoid code violations and water damage.

Digging and Preparing the Sump Pit

If you do not have a sump pit, you need to excavate one in the lowest point of your basement floor. The pit should be at least 18 inches in diameter and 18 to 24 inches deep—deeper if your water table is high or if you expect heavy inflow. Dig straight down through the concrete floor and into the soil below. This is the hardest part of the job and often requires renting a jackhammer or hiring someone to break through the concrete.

Once the hole is dug, line the bottom and sides with a sump basin—a plastic or fiberglass container that keeps soil from collapsing into the pit and allows water to collect without muddying the pump intake. The basin should fit snugly in the hole. Some basins have a lid with a hole for the pump discharge; if yours does not, you will need to cut one or drill one large enough for the discharge pipe to pass through.

If you already have a pit, inspect it for cracks, debris, or standing water. Clean out any dirt or gravel, and check that the basin sits level on the floor. A tilted pump will not work properly and may burn out faster.

Installing the Pump and Discharge Line

Place the submersible pump in the bottom of the basin. Most pumps sit on a rubber or plastic base that keeps them off the floor and away from sediment. Attach the discharge pipe (usually 1.5 or 2 inches in diameter PVC) to the outlet on top of the pump. Use a hose clamp or threaded fitting to make the connection watertight.

Run the discharge pipe upward and out of the basement, sloping it downward as it goes. The slope should be at least 1/4 inch per foot of horizontal run—this keeps water moving and prevents it from pooling inside the pipe. If the pipe runs outside, it should exit the foundation at least 10 feet away from the house, or connect to a municipal storm drain if one is available. Never discharge into a neighbor's yard or into a low spot that drains back toward your foundation.

Install a check valve on the discharge line just above the pump outlet. The check valve has an arrow showing the direction of flow; point it away from the pump. This valve closes when the pump stops, preventing water from flowing backward into the pit. Without it, the pump will run constantly as water drains back down.

If the discharge line runs through the basement wall, drill a hole slightly larger than the pipe and seal around it with caulk or spray foam. If the line runs up an interior wall, find it with pipe straps every 3 to 4 feet to keep it from moving or vibrating.

Electrical Connection and Safety

The pump's power cord must reach a GFCI-protected outlet. A GFCI outlet cuts power when ready if it detects moisture or a short circuit, preventing electrocution. If you do not have a GFCI outlet near the sump pit, you have two options: install a GFCI outlet in the basement wall, or plug the pump into a GFCI power strip rated for wet locations.

Do not run the pump cord across the floor where someone might trip on it. If the outlet is far from the pit, use a heavy-duty extension cord rated for outdoor use (even if it is indoors) and find it along the wall with clips. Never use a regular indoor extension cord—it is not rated for the moisture and vibration near a sump pit.

If you need to run new electrical wiring to the pit or install a dedicated circuit, hire a licensed electrician. Building codes in most areas require that sump pump circuits be installed by a licensed professional, and an inspector will need to sign off before you cover the wiring.

Testing the Pump Before You Seal the Pit

Before you close the pit with a lid, test the pump to make sure water flows out and the check valve works. Pour water into the pit until the pump turns on—most pumps have a float switch that triggers at a certain water level. Watch the discharge line to confirm water is flowing out and away from the house.

Let the water drain until the pump shuts off, then listen for a moment. If you hear water trickling back into the pit, the check valve is not sealing properly. Turn off the pump, check that the valve is installed in the correct direction, and tighten any fittings. Test again.

Once the pump runs and shuts off smoothly, and the discharge line is clear, you can install the pit lid. The lid should have a hole for the pump discharge and electrical cord, and it should fit snugly to keep debris and pests out of the pit.

Finishing Touches and Maintenance

Seal the gap between the pit lid and the basement floor with caulk or spray foam. This keeps radon and sewer gases from entering the basement through the pit. If the discharge line runs outside, make sure the end is covered with a screen or grate to prevent debris and animals from clogging it.

Set a reminder to inspect the pump every three to six months. Check that the discharge line is clear, the float switch moves freely, and there is no standing water in the pit between pump cycles. If water stays in the pit for more than a few hours after the pump shuts off, the pump may be undersized for your water table, or the discharge line may be clogged.

Keep the pump plugged in at all times during the wet season (spring and fall in most climates). If you unplug it to save electricity, water will accumulate and may flood the basement during a heavy rain.

When to Call a Professional

Hire a contractor or plumber if the sump pit does not exist and you do not have the tools or experience to break through concrete. Also hire a professional if the discharge line needs to run more than 50 feet, if you need to connect to a municipal drain system, or if the pit is deeper than 4 feet—these situations often involve permits and inspections.

Call a licensed electrician if you need to run new wiring, install a dedicated circuit, or if the nearest outlet is more than 25 feet away. An electrician can also advise whether your basement needs a backup power system (a battery or generator) to keep the pump running during a power outage, which is important in areas with frequent storms.

Frequently Asked Questions

Can I install a sump pump if I do not have a basement pit?

No, the pump needs a pit to sit in and collect water. If you do not have one, you will need to excavate one first. This is the most labor-intensive part of the job and usually requires professional help to break through the concrete floor.

What size pump do I need?

Pump size depends on how much water enters your basement. A typical residential pump moves 3,000 to 5,000 gallons per hour. If your basement floods during heavy rain, you may need a larger pump or a second pump on a separate float switch. A plumber can assess your water table and recommend the right size.

Do I need a backup pump or battery system?

A backup system is not required by code, but it is useful if you live in an area with frequent power outages or heavy storms. A battery-powered backup pump or a generator can keep water from accumulating if the main pump loses power. Many homeowners add one after experiencing a flood during an outage.

How often should the pump run?

In a properly installed system, the pump should run only when water reaches the float switch—typically once or twice a day in wet seasons, or not at all in dry months. If the pump runs constantly, the discharge line is likely clogged, the check valve is leaking, or the pit is too small for the amount of water entering.

What happens if the discharge line freezes?

In cold climates, water in the discharge line can freeze and block the pump outlet. To prevent this, bury the discharge line below the frost line (the depth at which soil does not freeze), or run it through the basement wall and into a storm drain. If the line is above ground, insulate it or use a heat tape in winter.