A flooded basement almost never has one cause. It is usually heavy rain, wet ground and a house that was built to shed water most days but not all of them. Cleanup starts with finding which way the water came in, because that decides whether it is clean enough to dry or contaminated enough to remove.
Where the water gets in
Where water gets into a basement
Numbered cross-section of a house with a basement showing six common water entry points: window well, wall crack or mortar joint, floor crack, cove joint where wall meets floor, sump pit, and floor drain.
Common entry points in a house with a basement. Your basement may have one, several or something not shown.
Most basement water comes in through one of six places. Window wells fill and leak through the frame. Cracks and mortar joints in block and stone walls let water through. Slab cracks and the cove joint, where the wall meets the floor, take water pushed up from below. The sump pit overflows when the pump cannot keep up. A floor drain can back up if the sewer line or municipal main is full.
The first four are groundwater. The last is a sewer, and sewer water changes the job. If it came up out of a drain, read sewage backup cleanup before touching anything.
How much rain does it take around Mechanicsburg
From 1991 to 2020 the Middletown-Harrisburg weather station averaged about 44 inches of precipitation a year in our calculation from NOAA daily data, with about 10 days a year of an inch or more. Two inches or more in a day happened about twice a year on average. Monthly averages run from about 2.6 inches in February to about 4.8 inches in September.
The creek tells the same story. NWS lists 86 floods at the Conodoguinet Creek gauge at Hogestown, which sits about 3 miles north of the borough. Its record crest was 17.01 feet in June 1972 from Hurricane Agnes, more than twice its 8-foot flood stage. You do not need the creek at your door for groundwater to rise.
The sump pump question
If you have a sump pump, check it first. A pump that runs all night in a storm can burn out, trip a breaker or lose power with the storm. A float switch can jam. A discharge line can freeze in January or clog with leaves. If the pit is full and the pump is silent, the basement is next. Our blog post on sump pump failure signs covers what to watch for.
Do not touch a sump pump or its cord while standing in water. Shut off power at the breaker only if you can reach the panel dry. If you cannot, call us and an electrician.
Water still spreading? Do not wait for it to stop on its own.
Call (223) 245-0005Finished basement or unfinished: what changes
| Situation | What we usually do |
|---|---|
| Bare concrete and block, boxes on shelves | Pump, extract, move and dry the contents, run dehumidifiers. Fast and cheap. |
| Carpet over concrete | Extract. Carpet may be saved with clean water caught fast. Pad usually comes out. |
| Drywall and insulation on exterior walls | Cut out wet drywall and insulation, usually a foot or two above the waterline, to dry the framing and block behind it. |
| Wood-framed walls on a concrete floor | Bottom plates and framing are dried. Anything that stays wet gets replaced. |
| Laminate or vinyl plank floor | Often lifted and discarded because water gets under the planks. |
What to do while you wait for us
- Stay out of standing water if anything electrical is in it.
- Photograph the water line on the walls before it drops.
- Move anything off the floor that you can safely carry. Cardboard soaks fast.
- Note when the rain started, whether the sump was running and when you found the water. Your adjuster will ask.
- Do not run a household vacuum or a gas-powered pump in the basement.
If the water came from rain or groundwater and not a pipe, many standard homeowners policies do not cover it, and flood is usually excluded unless you have separate coverage. Pennsylvania's insurance commissioner has said flood insurance through the National Flood Insurance Program takes 30 days to take effect, so it cannot be bought in a storm. Check your policy before you assume.
Where to read more about the ground under your house
The soil and bedrock under a basement decide how water reaches it. We cover that in the blog post on why Cumberland Valley basements take on water, and on each town page: Shiremanstown, Camp Hill and Carlisle. For the drying that follows pumping, see structural drying and dehumidification, and for storm-driven water, storm and flood damage.
Basement flooding questions
Is basement water from rain clean or contaminated?
Groundwater and rain are not as bad as sewage, but they carry soil and bacteria. We treat it carefully, and anything porous that stays wet for days is usually removed.
Will my homeowners policy cover basement flooding?
Standard policies often cover water from a sudden plumbing failure but not groundwater, flood or sewer backup. Some offer a water backup endorsement. Read your declarations page, and ask your agent.
How long does a flooded basement take to dry?
Extraction takes hours. Structural drying usually takes three to five days, longer for finished basements with insulated walls. We read moisture each visit.
Should I remove the drywall myself?
If you cut too little, mold grows behind it. If you cut too much, you pay for repairs you did not need. We mark the wet line first so the cut matches what is wet.
Can you prevent it from happening again?
We dry and clean. Fixing the cause, like a failed sump or grading problem, takes a plumber or a drainage contractor. We can tell you what we saw and where the water came in.
