Sump Pump Guide: Types, Sizing, Installation & Battery Backup

How a Sump Pump Works

A sump pump sits in a sump pit (also called a sump basin or crock) — a hole dug at the lowest point of your basement floor, typically 18–24 inches in diameter and 22–36 inches deep. Groundwater, rain water, and water from interior French drains flows into the pit through perforated sides or drain tiles connected to the pit. When the water level rises to a set point, a float switch activates the pump. The pump pushes the water through a discharge pipe to the outside of the house, depositing it at least 10 feet from the foundation (or into a storm drain where permitted).

Sump Pump Types

Submersible Pumps

The most popular type for residential use. The entire pump (motor and impeller) sits submerged inside the sump pit, below the water line. A sealed, waterproof housing protects the motor. Submersible pumps are quieter than pedestal pumps because the water muffles the motor noise, and the pit lid can be sealed to contain odors and moisture.

Pros: Quiet operation, out of sight (inside sealed pit), handles solids and debris well, more powerful options available, pit can be sealed for radon mitigation.

Cons: More expensive, shorter lifespan than pedestal (motor submerged in water), harder to service (must remove from pit).

Lifespan: 7–15 years.

Cost: $100–$400 for the pump. $300–$600 installed.

Pedestal Pumps

The motor sits on top of a long shaft above the sump pit (out of the water), with just the impeller submerged at the bottom. Pedestal pumps are visible above the pit and louder than submersible pumps, but they're easier to service and typically last longer because the motor stays dry.

Pros: Longer lifespan (motor stays dry), easier to service, less expensive, visible motor (easy to spot problems).

Cons: Louder, visible above floor, pit can't be fully sealed, less powerful than submersible, doesn't handle debris as well.

Lifespan: 15–25 years.

Cost: $60–$200 for the pump. $200–$400 installed.

Battery Backup Pumps

A secondary pump with a dedicated battery (or water-powered system) that activates when the primary pump fails or loses power. This is arguably the most important component of any sump pump system because the primary pump will fail exactly when you need it most — during a heavy storm that also knocks out your electricity.

Battery backup: A DC pump powered by a marine-grade deep-cycle battery and charger. Provides 5–12 hours of pumping on a full charge (depending on battery size and pump frequency). The battery charges continuously from household AC power.

Water-powered backup: Uses municipal water pressure to create suction and pump out the sump pit. No battery or electricity needed — works as long as you have water pressure. Uses 1 gallon of municipal water to pump 2 gallons of sump water. Cost: $200–$500 installed. Available only where water pressure exceeds 40 PSI.

1. Cost: Battery backup system: $200–$
2. 6
3. 0
4. Combination primary + backup system: $400–$1,000.

Sizing Your Sump Pump

Sump pump capacity is measured in GPH (gallons per hour) at a given head height (vertical lift from the pump to the discharge point).

1/3 HP: 2,000–3,000 GPH. Sufficient for most homes with moderate water intrusion. The most common residential size.

1/2 HP: 3,000–4,500 GPH. Recommended for homes with frequent water problems, high water tables, or larger sump pits. The best choice for peace of mind.

3/4 HP to 1 HP: 4,500–6,000+ GPH. For severe water problems, multiple drain tile systems, or commercial applications.

Head height matters: A pump rated at 3,000 GPH at 0 feet of head will pump significantly less at 10 feet of head (vertical lift). Check the pump's performance curve at your actual head height, not just the headline GPH number.

Installation Essentials

Check valve: A one-way valve installed on the discharge pipe that prevents pumped water from flowing back into the pit when the pump shuts off. Without a check valve, the pump cycles on and off repeatedly (short cycling), wearing out the pump prematurely. Every installation needs a check valve.

Discharge line: 1.5-inch PVC is standard for residential sump pumps. The discharge point must be at least 10 feet from the foundation and directed away from the house (and away from neighboring properties). In freezing climates, bury the discharge line below the frost line or use a freeze-resistant discharge with a pop-up emitter.

Pit liner: A rigid plastic or fiberglass liner that keeps the sump pit from collapsing and prevents soil from clogging the pump. Perforated liners allow water to enter from the surrounding soil. Every sump pit should have a liner.

Maintenance Schedule

Quarterly: Pour a bucket of water into the pit to test that the pump activates and discharges properly. Check that the float switch moves freely.

Annually: Remove the pump and clean the impeller and intake screen. Check the discharge pipe for obstructions. Inspect the check valve. Test battery backup (unplug the primary pump and test backup activation).

Every 3–5 years: Replace the battery in a battery backup system (marine batteries degrade over time even when maintained).