What is a sump pump?

What is a sump pump and what does it do?

It collects the water that seeps in under and around a basement or crawl space and pumps it out before it reaches the floor. FEMA and a Minnesota city code name the water it handles, from drain tile and from groundwater leaking into basements and crawl spaces: “Gravel sloped down outside of basement walls permits drain tiles or sump pump to remove excess water.” Source: U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center), read 2026-10-29. In Delano, Minnesota, “Dwellings and other buildings and structures which require, because of infiltration of water into basements, crawl spaces and the like, a sump pump discharge system shall have a permanently installed discharge line which shall not at any time discharge water into the sanitary sewer system, except as provided herein.” Source: City of Delano, Minnesota, read 2026-10-29.

How does Louisiana's plumbing code define a sump pump?

In plumbing code terms, a sump pump is the pump part of a three-part system: the pump, the sump pit it sits in, and the discharge piping that carries the water away. Louisiana's state plumbing code and Delaware's environmental agency define it: In Louisiana, “An automatic water pump for the removal of drainage from a sump, pit or low point in a residential, commercial or industrial property.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29. “A sump pump is used to remove water from a flooded area.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29.

What is the purpose of a sump pump?

Its purpose is to keep a basement dry when heavy rain saturates the soil and pushes groundwater in through the sump; Delaware's environmental agency adds that it is meant for stormwater, not everyday tidal flooding. FEMA and Delaware DNREC say: “Heavy rains result in soil saturation and can cause groundwater to enter through the sump.” Source: U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center), read 2026-10-29. “Sump pumps are not intended to remove everyday tidal flood water.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29. “They are better suited for stormwater removal.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29.

How does a sump pump work?

Water drains by gravity into the pit; as it rises, a level control (FEMA calls it the float switch) turns the pump on and it lifts the water up and out. Louisiana's plumbing code describes the gravity flow, the automatic pumping and a level control that keeps water at least 2 inches below the inlet pipe: In Louisiana, “The pit shall be accessible and located such that all drainage flows into the pit due to gravity.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29. “Building drains which cannot be discharged to the sewer by gravity flow shall be discharged into a tightly covered and vented sump from which the liquid shall be lifted and discharged into the building gravity drainage system by automatic pumping equipment or by any equally efficient method approved by the plumbing official.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29. “The effluent level control, etc., shall be adjusted and maintained to at all times prevent the effluent in the sump from rising to within 2 inches (51 mm) of the invert of the gravity drain inlet into the sump.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29.

What is a sump pump pit?

The sump pit, or sump basin, is the lined hole in the floor that the pump sits in. Louisiana's plumbing code sets it at no less than 18 inches across and 24 inches deep, with a solid bottom and a removable cover: In Louisiana, “The sump pit shall be not less than 18 inches (457 mm) diameter and 24 inches (610 mm) deep, unless approved by the plumbing official.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29. “The sump pit may be constructed of tile, concrete, steel, plastic or other approved materials.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29. “The pit bottom shall be solid and provide permanent support for the pump.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29. “The sump pit shall be fitted with a removable cover adequate to support anticipated loads in the area of use and to prevent refuse from entering the pit.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29.

What are the types of sump pumps?

Delaware's environmental agency names four types: submersible, pedestal, battery-operated backup and water-powered backup. This page only names them and makes no pick; the comparison linked below weighs one against another. DNREC says: “There are several types of sump pumps (submersible, pedestal, battery-operated backup, and water-powered backup).” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29. “If you experience deeper floodwaters or have a larger home, a pump with more horsepower may be necessary.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29. “Be careful to select one best suited to your home and flooding conditions.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29.

Does a sump pump need a check valve?

Under Louisiana's plumbing code, yes: the discharge piping of a sump pumping system needs both a check valve and a gate valve. FEMA describes check valves as devices that keep water from backing up into the basement and lists sump pumps among the lines that may need one: In Louisiana, “A check valve and a gate valve shall be installed in the pump or ejector discharge piping between the pump or ejector and the gravity drainage system.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29. “Discharge piping shall meet the requirements of §731.B of this code.” Source: Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute, read 2026-10-29. “Check valves or backflow valves are gate-like devices to keep water from backing up into the basement (homeowners should check with their local official to find out if the community permits these).” Source: U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center), read 2026-10-29. “Valves may be needed on washing machine drain lines, laundry sinks, rain downspouts, and sump pumps, as well as sewer/septic connections.” Source: U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center), read 2026-10-29. “All types of valves should have access so they can be cleaned out or repaired.” Source: U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center), read 2026-10-29.

How does a sump pump battery backup work?

A battery backup is a second pump for the times the main pump stops, the power goes out or heavy rain overloads it; FEMA says it starts when water in the sump reaches its float switch, and some models sound an alarm. FEMA and Delaware DNREC say: “Your basement can become flooded when your primary pump stops working, when the power goes out or when torrential rains overload the pump beyond its capacity.” Source: U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center), read 2026-10-29. “The backup goes to work when water in the sump reaches the float switch.” Source: U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center), read 2026-10-29. “Some of the newer models have a unique monitoring system that sounds an alarm when a maintenance issue arises.” Source: U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center), read 2026-10-29. “A portable generator may need to be rented/purchased for back-up energy.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29.

Can a sump pump discharge into the sewer?

Not where a city bans it. Delano, Minnesota is one example: its code bars sump water from the sanitary sewer and requires a permanent line to the yard or the city storm sewer, because rainwater has overloaded its treatment plant. EPA adds a rule for homes on septic: In Delano, Minnesota, “No water from any roof, surface, groundwater, sump pump, footing tile, swimming pool, or other natural precipitation shall be discharged into the sanitary sewer system.” Source: City of Delano, Minnesota, read 2026-10-29. “A “permanently installed discharge line” shall be one which provides for year-around discharge capacity to either an appropriate drainage area on the outside of the dwelling, building or structure (in no event shall such a drainage area include property owned by others or any public right-of-way), or is connected to the City storm sewer.” Source: City of Delano, Minnesota, read 2026-10-29. “Such damage is caused by the backup of sewage into the plant, private properties, and pressure damage to trunk lines.” Source: City of Delano, Minnesota, read 2026-10-29. “Placing: Keep roof drains, sump pumps, and other rainwater drainage systems away from your drainfield area.” Source: U.S. Environmental Protection Agency, read 2026-10-29. “The user must be careful that the water is not pumped into an area where it will flow right back into the flooded area or onto neighboring properties.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29.

How often should a sump pump be serviced?

Delaware's environmental agency says quarterly, following the maker's guidance, with a yearly check for rust or corrosion and a check that the discharge pipe is clear and drains fully. DNREC says: “Conduct quarterly maintenance based on manufacturer’s guidance and any permitting requirements.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29. “Inspect sump pump for rust or corrosion annually.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29. “Make sure that the discharge pipe is not obstructed and that it drains completely with no residual water remaining.” Source: Delaware Department of Natural Resources and Environmental Control (DNREC), read 2026-10-29.

What is a sump pump cover for radon?

It is a sealed cap on the sump pit that lets the pit keep draining water while a radon suction pipe draws from it; EPA calls this sump-hole suction, one of four soil suction methods for homes with a basement. EPA says: “In homes that have a basement or a slab-on-grade foundation, radon is usually reduced by one of four types of soil suction: subslab suction, drain-tile suction, sump-hole suction, or block-wall suction.” Source: U.S. Environmental Protection Agency, read 2026-10-29. “One variation of subslab and drain tile suction is sump-hole suction.” Source: U.S. Environmental Protection Agency, read 2026-10-29. “Often, when a home with a basement has a sump pump to remove unwanted water, the sump can be capped so that it can continue to drain water and serve as the location for a radon suction pipe.” Source: U.S. Environmental Protection Agency, read 2026-10-29.

Sources

• La. Admin. Code tit. 51, § XIV-731 - Sumps and Ejectors (Louisiana) — Louisiana Administrative Code (state plumbing code), via Cornell Legal Information Institute; published 2012-11; read 2026-10-29.
• I-ADAPT: Sump Pump (Flood Pump) — Delaware Department of Natural Resources and Environmental Control (DNREC); published 2023-03; read 2026-10-29.
• Mitigation and Basement Flooding — U.S. Department of Homeland Security, Federal Emergency Management Agency (copy hosted by the WV GIS Technical Center); published 2008; read 2026-10-29.
• City Code Section 606.01: Prohibited Discharges from Sump Pumps and Other Sources into the Sanitary Sewer System (Delano, Minnesota) — City of Delano, Minnesota; published 2009-02; read 2026-10-29.
• A Consumer's Guide to Radon Reduction: How to Fix Your Home (EPA 402/K-10/005) — U.S. Environmental Protection Agency; published 2025; read 2026-10-29.
• How to Care for Your Septic System — U.S. Environmental Protection Agency; published 2026-08-17; read 2026-10-29.