Water in the basement after a rain? Find out where it came in first.

Basement water after a rain comes in one of three ways: up over the top of the sump pit, up through a floor drain, or through the walls and the seam where they meet the floor. Each one has a different fix and a different person to call, and the spot where the floor got wet first usually tells you which one you're dealing with.

The rain on September 19 and 20 pushed Detroit's rainfall for the month above normal, after a dry stretch in late summer. Ground that's already wet going into October has less room for the next soaking rain, so if you found a puddle last weekend, it's worth figuring out where it came from instead of just mopping it up.

Start with where it's wettest

The spot that got wet first, or stays wettest, is almost always closest to where the water came in. Water spreads toward the low spots in a basement floor, so by the time you find it the whole corner may be damp, but the source usually still shows: a wet ring around the sump pit points to the pit, a puddle centered on the floor drain points to the drain, and a damp line along the bottom of a wall points to the wall.

If you can't tell, dry everything with towels or a wet vac and check again during the next rain. Seeing it happen once is worth more than any amount of guessing.

Up over the top of the sump pit

If the water started at the sump pit, the pump either stopped or couldn't keep up, and that's the one on this list we fix. Look in the pit. If it's full to the rim and the pump is quiet, check the simple things first, like whether it's plugged in, whether a GFCI outlet tripped, and whether a breaker flipped. Then lift the float gently, or pour a bucket of water into the pit, and see if the pump starts.

A pump that hums but doesn't move water, starts and stops without emptying the pit, or ran all night and still lost the race is telling you something, and our guides to the signs a sump pump is failing and a sump pump that runs constantly walk through what each one means. If the power went out during the storm, that's its own problem, and what to do when the power's out covers it.

Up through the floor drain

Water that came up through a floor drain is a sewer problem, not a sump problem. It usually comes up murky or gray, it may smell like sewage, and it tends to show up during the heaviest part of a storm, when the sewer lines are full and the water backs up through the lowest opening in the house.

Treat it as contaminated. Wear gloves and boots, keep kids and pets away from it, and hold off on the sinks, toilets, and washer upstairs until it's sorted, because that water heads into the same line. If you're on city sewer in Novi or Farmington Hills, call your city's water and sewer department to report it, since a backup in the main is theirs to deal with, and if the main is clear, the blockage is in your own sewer line and a sewer cleaning company is the right call. In a house on a septic system, which is common around Milford and Highland, water coming up a floor drain means the septic system or the line to it needs a look.

There's one exception. In some older homes the floor drain is piped into the sump pit, so if the water around the drain is clear and the pit was overflowing at the same time, it's still the pump.

Through the walls

Water along the bottom of a wall, at the seam where the wall meets the floor, or coming from a crack or a window well is pushing through the foundation from the soil outside, and it's usually there because rain is soaking in too close to the house.

Start outside, because that's where the fix usually is. Check that the gutters aren't overflowing, that every downspout empties several feet from the foundation instead of right at the corner of the house, that the ground slopes away from the walls, and that the window wells aren't filling up like buckets. Follow the sump pump's discharge line while you're out there too, since water it dumps next to the house soaks right back in, which we covered in checking the discharge line this fall.

If the outside all looks right and the walls still leak, that's a waterproofing or drain tile question, and a basement waterproofing contractor is the person to call.

Or it wasn't the rain at all

If the floor is wet and it hasn't rained, look at the appliances before you look at the foundation. A leaking water heater, a washing machine hose, or condensation dripping off cold water pipes on a humid day can all leave a puddle that looks a lot like a leak from outside. Water pooling around the base of the water heater is the one to take seriously, and what to do when a water heater is leaking covers the first steps.

Before the next rain

Once you know where it came from, a few minutes now saves the next mop up. Test the sump pump with a bucket of water, clear leaves out of the gutters and off the discharge outlet, and put back any downspout extension that got moved for the mower. If your pump is getting older or has already failed once, a battery backup is what keeps it running when a storm takes the power with it. Our sump pump page covers everything we install and repair in Milford, Novi, and Farmington Hills.

Quick answers

How do I know if my sump pump caused my basement to flood?

If the water started at the pit, the pit is full to the rim, and the pump isn't running or can't keep up, the pump is the cause. Check the power, the outlet, and the float, then test it by pouring a bucket of water into the pit.

Why did water come up through my basement floor drain?

Usually because the sewer line it connects to was full or blocked, either the city main during heavy rain or your own line. It's a sewer problem rather than a sump pump problem, and the water should be treated as contaminated.

Is water along the bottom of a basement wall a sump pump problem?

Usually not. It's groundwater pushing through the foundation, most often because gutters, downspouts, or grading are sending rain toward the house, so fix the outside first.

Countryside Plumbing is a licensed master plumber serving Milford, Novi, Farmington Hills, and southeast Michigan since 1979. Sump pump installation, repair, and battery backups are a big part of what we do. Free quotes at 248-705-7543.