What happens to the water in your school?
Rainwater which falls on the roof of your school is collected in the gutter and drainpipes take it down into the sewer. Rainwater falling on your school playgrounds and car park flows towards gutters and drains and also down into the sewer.
Other pipes also take dirty water from the school bathrooms, sinks and kitchens into the same sewer. Dirty water from the toilets is called foul water, the water from the sinks and kitchens is called grey water – this water is not as dirty as the foul water from the toilets.
We often have combined sewers which mean the rainwater, grey water and foul water all go to the same sewer pipe, they mix together and all get treated at a sewage works.
Our climate is changing, and we are having more and more heavy rain showers where a lot of rain falls very quickly. Our sewers were built a long time ago and are too small. When it rains heavily the rainwater fills up the sewer, and there is nowhere for the water to go. This causes flooding as the drains are full. It also causes overflow valves (called combined sewer overflows) to open and a mixture of foul water, greywater and rainwater to go into our rivers causing pollution.
But what can you do about it?
You can help by building raingardens!
You can help reduce flooding and stop dirty water overflowing into our rivers by slowing down rainwater on its way to the sewer. You can do this using raingardens. You may also hear raingardens being called sustainable drainage or SuDS.
Raingardens use plants, soils and the landscape to hold onto the rainwater and then slowly release it. They also help reduce the amount of water which gets to the sewer. Some water is taken up by the plants, some rainwater finds its way back down into the ground, and some water will evaporate. Raingardens also help clean the water, which may have picked up dirt from the roofs and roads.
This school has used raingardens to slow down the rainwater. You can see raingarden planters coming off wiggly drainpipes, a swale with places to sit by it, a small wetland, and lots of different green roofs. It might not always be possible to do everything, but even small changes help. You could find out more information about raingardens, write down or draw your ideas, and talk to your teachers or Eco Council about your suggestions.
Why not just build bigger sewers?
We could build bigger sewers, but this is expensive and may not be the best solution. Rainwater doesn’t need to be sent to a sewage works before it finds its way back to the river. Raingardens also give other benefits to us humans and to wildlife.
Raingardens can provide us with beautiful places to sit, walk through and look at. They provide a space for nature,
giving insects and birds a home and food. The plants which grow in raingardens help improve air quality and water quality. By slowing down the rainwater, and stopping it getting to the sewers so quickly, raingardens help to reduce flooding and protect our rivers.