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Causes of a Blocked Stormwater Drain

Your home’s drainage system consists of gutters, down pipes, and drainage pits that direct the flow of water away from your house to the stormwater drain in the street in front of your house. If you see water pooling around your yard or house or water is overflowing from your gutters, you probably have a blocked stormwater drain and will need professional stormwater drain cleaning. Typically, a stormwater drain gets backed up during a weather event like a severe rainstorm, but there are other causes as well.

Environmental Blocks

The most common cause of a blocked stormwater drain is the presence of environmental objects like leaves, pebbles, sticks, dirt, and sand. If you have a garden that is filled with mulch or bark, that matter can also make its way to your stormwater drain and can lead to a blockage. When it rains or when snow melts, it can pick up and carry almost anything in its path. But, when it hits a grate or a pipe, the water keeps going, while the solid objects stop.

Some smaller environmental matter can get through larger pipes, but even then if the stormwater drain isn’t cleaned often enough, this debris will accumulate as well and lead to a blockage. Eventually, some of this matter will decompose, especially if it’s matter like leaves or grass, but it takes a while to get to that point and until that happens, the water will stop flowing freely down the drain.

Non-Environmental Blocks

Non-environmental stormwater drain blocks are becoming more of an issue all the time. These blocks are the result of non-organic matter like plastic bags, bottles, food wrappers, cups, and other rubbish that gets tossed out of car windows or gets blown out of rubbish bins by the wind. These items are more problematic than things like leaves and dirt because they take much longer to decompose, can cover more surface area on a grate, can plug up larger pipes, and don’t usually move without assistance.

For example, if a plastic bag gets washed down a street and hits a grate, the bag will spread out and cover more of the grate than leaves or grass would. It takes much less time for a stormwater drain to become blocked with items like plastic bags than with smaller items, so drains that are impacted by a lot of refuse in an area (like city stormwater drains) usually need to be professionally cleaned more often than those in residential areas.

Another non-environmental block that can occur in a stormwater drain is an improper connection between the sewer pipes and drain. If the connection isn’t tight, not only will the water leak, but it can also back up into streets or yards. A good connection allows for the proper amount of fall so that gravity helps the water drain, but a bad connection might not have enough fall, which leads to the water pooling and eventually backing up.

Preventing a Blocked Stormwater Drain

You can’t prevent blocked stormwater drains entirely, but you can take measures to keep them as clear as possible. If you live in an area with lots of leafy trees, make sure to rake your lawn regularly and put the leaves in the garbage so they aren’t loose when a storm comes. This will keep the leaves from flowing to the stormwater drain in the first place.

If you have a garden, keep the borders maintained well so that the mulch and bark can’t escape as easily when it rains heavily. In areas that get a lot of rain, gardens may need slightly higher borders to contain the soil, mulch, and bark when the water level rises.

Keep your gutters free from debris so that they don’t get backed up to the point where water is spilling over their sides. Your home’s drainage system is specifically designed to keep the flow of water moving in the right direction. If anything gets in the way of that flow, it can lead to a blocked stormwater drain.

Clearing a Blocked Stormwater Drain

In many cases, you can clear the blockage yourself, especially if you can see what’s causing the blockage. For instance, if you see that there is trash accumulated in front of the grate leading to the stormwater drain, removing that trash will often solve the problem.

On the other hand, if you can’t see what’s causing the blockage because it’s in the pipe itself, hiring a professional stormwater drain cleaning company is the best option. It will save you both time and money to have a professional take care of the problem.


A blocked stormwater drain can cause numerous problems for homeowners, such as lawn flooding and foundation leaking. If you notice your stormwater drain is backing up, it may be time to get it professionally cleaned.