Diagnosing the problem

The truth of the matter is that most basement water problems are not basement problems at all, but exterior drainage problems. So before you consider a sump-pump installation, take a good look (in the rain, if you must) at the drainage around your home. Make sure that gutters aren't clogged, that downspout extensions move roof runoff at least 4 ft. beyond the foundation and that the soil within 3 ft. of the foundation slopes away from the house.

Even if these conditions have been met, water may still accumulate in your basement. The problem may be a utility trench that invisibly channels runoff back to the house or a seasonally high ground-water table. In these cases, a sump-pump installation is a good solution.

Many new homes have a sump pit already in place, complete with a drainage-tile system under the basement floor that's designed to channel water to the pit. If your home doesn't have this feature, and your water problem affects most of the basement, a retrofit system of this type is a good option. However, it's a big job that involves removing a 24-in.-wide swath of concrete and soil from the inside perimeter of the basement, adding gravel, draintiles and a pit and replacing the concrete.

While this isn't an impossible DIY job, it's backbreaking work. You can pay a professional $2500 to $5000 to do it for you--not necessarily a bad price, though, considering that you'll perhaps double your living space.

A more manageable approach, in the right circumstances, is to install an isolated sump pit with several feet of gravel around it. To have this system installed may cost between $300 and $500. Or, you can devote a few weekends to the job and do it yourself for the price of the pump, pipe and fittings, pit liner, gravel and cement.

This abbreviated system is most appropriate where water infiltrates only one area of the basement, or where the basement floor was poured over a gravel bed. Many homes built over the past 30 years have several inches of gravel beneath the concrete floor. The gravel was used to bring a slightly over-excavated floor back to grade. Because water seeks the path of least resistance and will migrate sideways before it moves up, moisture beneath the floor will move through the layer of gravel to a sump pit before flooding the floor.

Unfortunately, it's difficult to tell if your basement floor floats on a gravel bed. The builder of the home or a neighbor who has done similar work might know. In most cases, though, you won't know until you break through the floor. Sometimes, a few holes bored through the floor with a hammer drill will reveal the information you need.

Steps:

1 Set sump basin upside down on basement floor; mark its outline on floor.
2 Use demolition hammer to chop through concrete floor.
3 Dig hole deep enough to set basin flush with floor.
4 Wrap the sump basin with filter fabric.
5 Set the basin in the hole.
6 Add several inches of gravel to basin.
7 Lay stone paver on top of gravel.
8 Set pump on top of paver.
9 Connect check valve and PVC pipe to pump; run pipe up a nearby wall.
10 Drill hole through house wall with hole saw.
11 Continue PVC pipe through wall and extend to the outdoors.
12 Mix concrete in trough using a hoe.
13 Fill in around the basin top with concrete; smooth the concrete with a pointed trowel.
14 Plug in pump, then test it by filling the basin with water.