Let them flow: keep your stormwater drains blockage-free

It’s important to remember that stormwater drains are only meant to carry stormwater – it’s in the name. You should never pour chemicals or paint into a stormwater drain. Apart from being illegal, this can harm wildlife, pollute our river systems, and adversely affect the condition of your pipes. Oil and grease can also solidify in a pipe, making it harder to be washed away. 

While it might be tempting to hose those leaves and lawn clippings off the pathway into the nearest drain, any organic material that goes into the stormwater drain may become lodged in the pipe.

If you have open drains, make sure they’re fitted with a grate to prevent debris from getting into the pipes.

During storms, watch for rainwater backing up or spilling from drains or, worst case, filling up the down pipes all the way to the guttering. This signals a blockage. If there’s no rain on the way and you want to test the flow rate, you can run a hose, without any fittings on the end, into the drain or down the downpipe. Check how quickly the water flows away. If it’s working properly, the pipe shouldn’t fill with water. 

If you know where the drain empties out into the street, check to see if the water is flowing freely out the other end.

Regularly running water through the drains will also help to flush out any accumulated dirt or debris.

If you think there’s a blockage that can’t be budged by running water down the drain, it’s time to turn to more specialised tools. There are a variety of drain ‘snakes’, also known as electric eels, that you can borrow, hire or buy. 

These are long coils of flexible metal cable. You can feed them down the drain to dislodge a blockage or extract material. Make sure you use one long enough to extend the entire length of the pipe. 

Special high-pressure cleaners pump a powerful jet of water through a hose to clear out major blockages, such as tree roots. These can be hired from equipment hirers. 

Drain clearing chemicals typically used inside the house for sink blockages shouldn’t be used with stormwater drains. They’re mainly designed to dissolve hair and fat blockages.

Trees are a lovely addition to any garden, but they can be a menace for stormwater drains. Tree roots can infiltrate pipes, causing blockages. Houses with older ceramic pipes are particularly at risk as the roots will seek out any cracks or weaknesses in the pipe. 

If you suspect root problems, hire a licensed plumber to inspect the inside of the drain with a camera. They will then be able to offer solutions for clearing the pipe, which may include water-jetting, relining the pipe, or even replacing it entirely.