Do I need a sump pump in my basement?

Not every basement needs a sump pump. You need one when groundwater rises up under or into the basement, or when the house was built with a sump pit, which then needs a working pump in it. If water only comes in during heavy storms, the cause is usually outside, in the gutters, downspouts or grading, and fixing that first is usually simpler than adding a pump.

What a sump pump is for

The Northern Virginia Soil and Water Conservation District defines a sump as a small reservoir at a low point that collects water, and notes that many households have one designed into the foundation or slab to collect groundwater so it does not flow into the basement.^[1] A sump pump is the device that pumps that water through a pipe to the outside of the house.^[1]

The pump only works on water that reaches the pit, from drain pipe around or under the foundation, or from water rising beneath the slab. Fairfax County's flood program describes a sub-slab drainage system as perforated drainpipes under the lowest floor, connected to a sump pump, that catch groundwater rising from below and pump it outdoors before it reaches the floor.^[4] It says such a system is used primarily for groundwater rising from below, not for drainage problems at the ground surface, and that it is important to find the cause of the problem first.^[4]

Signs you probably do need one

• There is already a pit. A pit in the floor means the builder expected groundwater. Keep a working pump in it rather than leaving it empty.
• Water comes up through the floor. Damp patches or water in the middle of the slab, or seeping at the joint where floor meets wall, often after a long wet spell rather than one storm, point to groundwater.
• The basement is finished or holds equipment. The more a flood would damage, the more a pump, and a backup for it, is worth.

Signs the problem is outside

If water appears along one wall during or just after a downpour, start outside. The conservation district says: "Most wet basements are a result of water problems outside of the house."^[2] Its list for a wet basement is to make sure the sump pump is on and working, clear basement stairwell drain grates, check the grading around the home, deal with gutter and downspout problems, and call a professional if the problem remains.^[2]

The ground next to the house should slope away from it. Ideally the ground keeps a 5% grade for ten feet around the house.^[3] In a hard rain, an average-sized house can shed hundreds of gallons of runoff from its roof, and downspouts and sump pumps that are not set up correctly can cause foundation problems, erosion or wet spots in the yard.^[3] Gutters that overflow or downspouts that empty against the wall are common culprits.

If you can solve a drainage problem from outside the house, Fairfax County's flood program says, that is almost always preferable and simpler than solving it from inside.^[4]

If you already have a pump

Keep it working and think about power cuts. Ready.gov's flood advice includes: "Consider a sump pump with a battery."^[5] Wayne's sump pump manual recommends an independent high water alarm or backup pump where high water could damage property.^[6] Test the pump a few times a year; how to test a sump pump walks through it.

Hiring someone to add one

Adding a pump to an existing, empty pit is a modest job. Creating a pit where there is none is not. Fairfax County calls a new sub-slab drainage system a major project requiring demolition, wiring, plumbing and permits, warns that if it is not done carefully it could make drainage problems worse and damage buried infrastructure, and tells applicants to contact Miss Utility at 811 before they begin.^[4]

Permits. Pittsylvania County lists sump pumps among the work that needs a building permit.^[7] Requirements vary, so ask your county or city building department, and make sure the contractor's quote says who pulls the permit.

Where the water goes. Spotsylvania County lists groundwater sump pumps among the improper connections to a private sewer lateral.^[8] The discharge should end outdoors where the ground can take it. The conservation district's glossary adds that your property line is not a suitable place to discharge water.^[1]

Licences. Virginia law requires the Board for Contractors to make a master tradesman licence a condition of licensing a plumbing or electrical contractor.^[11] The Board for Contractors tells homeowners to check that a contractor is properly licensed for the work, to get at least three written bids, and that Virginia law requires licensed contractors to provide a written contract for residential work.^[10] Costs vary widely with the job; see what sump pump installation costs in Virginia.

Questions worth asking each contractor: what do you think is causing the water, can any of it be fixed outside, where will the pump discharge, does the price include a backup and an outlet, and is a permit included?

Stop and call a pro if

• You see cracks in basement walls or the foundation along with the water. The conservation district says wet basements and wall or foundation cracking can have serious consequences for a home's structural integrity and your health, and should be addressed right away.^[2]
• There is standing water near the electrical panel, a furnace or a water heater. Wayne says not to walk on the floor while water is present until all power is off, and to call an electrician if the electrical panel is in the basement.^[6]
• Water backs up out of a floor drain, or the water smells of sewage. That is sewage, not groundwater, and a sump pump is not the fix. The City of Salem's sewer backup advice says to turn off a sump pump during a backup, and that if the issue appears to be affecting one building, contacting a licensed plumber is recommended.^[9]
• The gutters need cleaning but you cannot reach them from the ground or a short stepladder, or they are on a second storey. That is ladder work for a gutter cleaning pro.
• Water keeps rising through the floor after the outside fixes.
• Mold is growing on walls or stored belongings.

Getting help on Loclis

Browse sump pump installers or plumbers in Blacksburg, or read more plumbing answers. If you are replacing a pump in an existing pit, see how to replace a sump pump.

To have licensed local businesses look at your basement and quote, describe your sump pump job once on Loclis.