Reduce Your Home’s Stormwater Runoff

R. L. Rhodes
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Is water that should be nourishing your lawn and garden washing away fertilizer and running down the drain instead? Use these steps to reduce the amount of runoff escaping from your property.

The water that flows off of your landscape when it rains or when accumulated snow melts is often referred to as stormwater runoff. As it washes across your land and down storm grates or into nearby bodies of water, runoff can carry away soil, chemical lawn treatments, and debris.

This runoff not only erodes your landscape and frustrates attempts to treat your lawn, but it can also pollute the local water supplies on which you and your neighbors rely. Some yards are so prone to runoff that very little water actually makes it into the soil itself, making it difficult to adequately nourish grass and other plants.

Luckily, there are ways that most homeowners can reduce the amount of runoff that flows from their property. The following tips provide a general strategy for managing runoff and making sure that less of the water needed by your landscape ends up in storm drains.

Reduce impermeable surfaces

The next time it rains, grab an umbrella, go out into the street, and trace the water flowing along ditches and gutters back to the points where it leaves your yard. Chances are, it’s cascading off of a solid surface, like a roof or driveway, which prevents rain from soaking into the ground. Ecologists call those barriers “impermeable surfaces,” and they’re a major cause of storm water runoff, particularly in urban areas.

One way to curb runoff is to reduce the number of impermeable surfaces in your landscape. That allows water to stand long enough for the ground to absorb it. Start by taking stock of the surfaces in your landscape. Which ones are impermeable, and which of those can be replaced with a more permeable alternative?

It’s difficult to find a less permeable landscape feature than new concrete sidewalks and asphalt driveways. The same functions can be accomplished with surfaces composed of small pavers and unfixed gravel, allowing rainwater to penetrate to the ground rather than spilling out into the street.

The roof is trickier, but if you have a relatively level grade, you might consider looking into converting yours into a green roof. If that’s an option that appeals to you, contact a contractor in your area and ask them to come out for an assessment.

Redirect the flow of water

Some homes and landscapes are simply built to shed water.

For a relatively simple illustration, consider the drain spouts attached to the gutters on your roof. Where do they empty? If the spout opens over a paved surface, like a driveway, kiss that water goodbye. It’s likely to flow down that impermeable surface and off of your property. Adjusting rain spouts to empty onto vegetated ground will ensure that more of the water flows where it’s needed.

Managing the flow of water is not always so easy, though. Some homes are built on slopes, and some lawns were even deliberately sloped in order to push stormwater into the street or onto someone else’s property. If your lawn is sloped, you might consider leveling it to restrict runoff.

Of course, in some regions, perfectly level lawns are simply not an option. If leveling your lawn isn’t really possible, consider building up earthen barriers (called berns) or excavating gradual depression (swales) to slow and redirect the flow of water from your land. Hills can sometimes be terraced to slow runoff, and a well-placed row of plants can help as well.

Catch some of the runoff

Even if tearing out your driveway and replacing it with a new one isn’t practical right now, there are features you can add that may help your yard keep more of the water that falls there. For an easier, more economical approach, see our project on adding runoff trenches that can capture some of the water flowing from your driveway. Likewise, if the grade of your roof is too steep to convert it into a green roof, you can, at the very least, install a rain barrel or two to catch the runoff coming from your existing roof.

If you see water running off of even level stretches of your yard, it’s possible that compaction has turned your landscape into another impermeable surface. Check out our article on core aeration for tips on how to make your soil more permeable and your lawn healthier.

If compaction isn’t the problem, you might consider building a rain garden — basically, a sunken garden plot for plants that thrive in soggy environments. Rain gardens catch and hold precipitation, allowing your soil the time it needs to soak up the excess. Check with your local county extension office for native plants that don’t mind getting their feet wet, and be sure to call 811 to find out the location of underground utilities before digging in your yard

Reduce exposure

Ultimately, it may be impractical to prevent every last drop of water that falls on your landscape from running off, but with a little care, you can ensure that the remaining runoff poses little or no health threat.

Many of the household chemicals that make our lives easier can pollute local water sources when carried into storm drains or waterways by runoff. Make sure that you’re properly storing pesticides, fertilizers, pool treatments, automobile fluids, cleaning agents and other chemicals. Dispose of them properly, recycling whenever possible.

Do not dispose of them by emptying them into storm drains or on the ground. When using them, follow the manufacturers instructions. Particularly with lawn and landscape treatments, be careful to avoid over-treating your landscape as the excess can be easily washed away by runoff.

Likewise, the drip of oil or antifreeze that seems relatively contained in your driveway can easily be swept into local water sources by a heavy rain. Periodically tune up your cars and motorized equipment to avoid leaks that could find their way into the water supply. If you notice a leak, but can’t get it fixed right away, you can still help keep it from getting washed into the water supply by putting a pan or carpet scrap beneath the leak.

Image by John Holm/Flickr.

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