Swales, Berms, And Other Ways To Prevent A Wet Basement

Swales, Berms, And Other Ways To Prevent A Wet Basement

If your home is in the middle of a wide swath of land, or if you have a lot of property, it may be harder to keep your basement dry. People living in tract home developments might have an easier time avoiding a wet basement, since the land around them has been landscaped and designed to flush water away from the homes. This doesn’t exempt development dwellers from all basement waterproofing efforts, of course, but it does make life a bit easier.

But those of us living on wide parcels of land must find ways to channel water away from our homes. One simple way to prevent a wet basement is by installing a system of swales and berms on your property.

Sound complicated? It’s actually not. By managing your property in a way that draws water away from your home — into a retention pond, a dry well or a nearby stream — you’ll avoid all the perils that come with a wet basement, like foundation damage and mold growth.

Here’s a quick tutorial:


Swales are drainage ditches, plain and simple — and they’re the best way to keep rainwater from creating a wet basement. And despite what you may fear, swales don’t have to be two-foot deep culverts lined with plastic. Go down six to ten inches and across about three feet, fill the bottom with gravel and topsoil, and plant a long-rooted grass in the topsoil.

The complicated part of installing swales on your property is determining where they should go. Swales should always run downhill, and they should encompass enough of your property that no pools form anywhere during heavy rains. Ultimately the swales should lead to a common drainage area such as retention pond.


These are an important component in avoiding a wet basement. Berms are raised areas of ground that encourage water to drain downward, away from your home. These should be built up around your home’s foundation and lead water away from it, toward the swales, which can carry it away to a common location.

The tricky part of installing berms is to make sure they don’t trap water against your home’s foundation. Always make sure they lead stormwater away from your home rather than toward it. Think of berms as methods of feeding water to thirsty swales.

Window Wells

If your berms are flush against your home’s foundation, you may need window wells to ensure that your basement windows aren’t covered by dirt. But basement windows are an easy path toward a wet basement, so make sure they’re properly sealed.

To install a window well, cut a half-circle into your berm up against the relevant section of foundation, about a foot deeper than the bottom of the window. Insert a liner into the hole — the liner should extend at least three inches on either side of the window, and should be smaller than the hole by a few inches as well. Spread about four inches of gravel inside and outside the liner, and fill the space between the liner and the ground with topsoil. This is the best way to keep your windows from creating a wet basement.