The first rain during a drought provides some welcome relief, but for our storm overflows it can sometimes be hard to handle.
As the ground is so dry, the rain can just run off and causes flash floods. This sudden influx of water puts extra pressure on our sewer systems. Most of the country has a combined sewer system meaning rainwater flows into the same network as our wastewater.
Dry weather and our network
During dry weather, less water flows through the sewer, leaving some of the heavier items that shouldn’t be flushed – like wet wipes, sanitary items and grit – to settle at the bottom of the pipes.
What happens when it rains?
Rain falls onto the dry, hard ground, which then can’t absorb the water. Most of the rain runs off the ground and runs down gutters, through drains and into the sewer network.
This extra water moves the wet wipes and other rubbish that’s been sitting on the bottom of the pipes and carries it along to our treatment works. As well as the possibility of the volume of water overwhelming our sites, if these unflushable items cause blockages in the network or get stuck in the wrong equipment, they can cause big problems.
This can then trigger an emergency release through a Combined Sewer Overflow – or storm overflow – to prevent the water backing up and flooding homes and businesses. The screened, heavily diluted wastewater is released into local watercourses. This is allowed by the Environment Agency to protect our communities.
Would you like to know more about how Combined Sewer Overflows work?
We’ve answered your questions here (link in bold)
What type of rain will help?
For any rain to make a real difference to our river and groundwater levels, we need a constant, light drizzle that will really soften the earth and let the rain trickle down and refill our underground aquifers.
Until we get this kind of rain, it’s difficult for our river and groundwater levels to recover. It means we’ll need to keep saving water until we’ve had enough rain to restore the soil to normal, so we can start to see our water source levels increase.
Your help makes a big difference
Thank you for your help to save water and only use what you need. Last week we saw an 8% decrease in demand for water, compared to the week before – enough to fill 12,000 tanker trucks.