Wet basement after a storm? Trace the water first

The first hours after a storm

• If water is near outlets, the furnace or the electric panel, stay out and have the power shut off first.
• If the water came up through a floor drain or a toilet and smells of sewage, treat it as contaminated.
• Take photos and short videos of where the water is and where it seems to be coming from, before cleanup. Those clues disappear once the floor dries.
• Move boxes and rugs, get air moving, and run a dehumidifier.

Four places water comes from

A wall. A damp patch or a line from a crack, or a block wall that darkens from the bottom up. The floor joint. A ring of water along the edge of the slab, often from groundwater pressure after a long rain. A window or well. Water running down the inside of a basement window, usually from a well that filled. A pipe. A supply line, water heater, washer hose or condensate line, which leaks whether it rains or not.

A simple test helps sort a wall from the air: tape a square of plastic to the damp spot for a day. Moisture under it is coming through the wall; moisture on top is condensation.

Seepage or sewer backwater?

Clear water that rises slowly at the walls and floor edge is groundwater seepage, and it is what interior drainage is built for. Water that rushes up through a floor drain, especially during very heavy rain, is often the sewer or storm system backing up. After Ida, the state described damage to "already deteriorating sewage and stormwater networks" (NJ DCA Ida report). Backwater calls for a plumber and possibly a backwater valve, not drain tile, and the visit will tell you which one you have.

Matching the fix to the source

• Water at the floor joint along one or more walls: interior drain tile to a sump.
• A single wet crack in a poured wall: crack injection.
• A pit that overflows or a pump that quit: a new pump or a backup.
• A well that floods the window: a well drain and cover.
• A downspout dumping at the foundation: an extension, which costs very little.

Often it is two of these at once, which is why the order matters. Fix the cheap, obvious source first, then see what is left.