March 8, 2018
With the UK population on the rise, drainage systems are facing added pressure. Educating the public about ‘toilet rules’ – no wet wipes – is working
UK water consumers take it for granted that waste water will be disposed of appropriately. However, most people don’t know what happens after they flush the toilet or pull the plug in their sinks.
Water operators have worked hard to reduce the likelihood of flooding and pollution from their sewer networks. While there is still much to do, we now have rivers abundant with life and bathing waters to be proud of. Clean beaches attract visitors and support communities, jobs and the economy.
This has all been possible because the UK water sector has invested £39bn (€45bn) over the last 25 years in improving the sewage system and more on maintaining the country’s sewer network. Sixteen billion litres of waste water a day goes through 624.000km of sewers, 9.000 waste water treatment plants and about 15.000 combined sewer overflows (CSOs). The UK water sector plans to invest even more to further improve the sewer network.
Combined sewer systems
When the Victorians started to construct sewer systems to meet the needs of towns and cities, they built what we call ‘combined sewers’. These transport sewage and surface water (mainly rainfall) to waste water treatment works for cleaning, before this water is returned to the natural environment.
These work well the majority of the time. But very heavy rainfall can rapidly increase the amount of water flowing through combined sewers. Sometimes, the amount of waste water collected exceeds the sewer capacity (something that may happen more often if we get the more intense rainfall that scientists predict). And sometimes sewers can back up because of blockages caused by people tipping fats and oils down the sink or flushing wipes and sanitary items that the sewers weren’t designed to cope with.
Combined sewer overflows
When sewers are overwhelmed, the excess water is channelled away from homes, businesses and land, avoiding flooding. This is currently done using combined sewer overflows (CSOs), which act as a relief valve. Overflow water is diluted by storm water within the sewer network at the time and further diluted by the flow in the streams and rivers they flow into, as these will also be swollen due to heavy rainfall. The water is screened, where necessary, to remove most of the plastics and other materials, which find their way into sewers and drains. If our sewer systems didn’t have CSOs, more homes, businesses and land would flood.
When a few CSOs overflow, they can have a significant impact on the environment. Water operators are increasing investment in monitoring CSOs so they can better understand the effect they have on wildlife and find ways of dealing with the ones that have most impact on the environment.
CSOs are also regulated by the UK’s environment regulators. But the heavy rain predicted by climate change scientists could mean that even these relief valves will not be able to cope.
Companies already face some large challenges and these will only increase. Water operators invest in the network so that the drainage system can meet these challenges in order to avoid flooding and pollution. These challenges include:
- Changing weather patterns due to climate change.
- New environmental standards to better protect and enhance our rivers and seas.
- Population and development growth and smaller household size. These will lead to more houses, roads and other developments being built. As a result, there will be fewer areas for water to soak away naturally and more water flowing straight into combined sewers.
- How best to inform customers about what the sewer network can carry – only toilet paper, pee and poo.
- Separating sewage from surface water in sewer pipes to reduce the risk of flooding. And all this is set against customers’ challenge to companies for better service at a lower cost.
Creative and innovative solutions
Upgrading the sewer network to accommodate these extra pressures is expensive. Water operators work hard, in partnership with regulators, local authorities and environmental and customer groups to get the right balance between reducing the risk of flooding and pollution and maintaining affordable bills.
We’ve moved on since Victorian times, developing creative and cost-effective ways of removing storm water from the sewer network to reduce the risk of flooding and pollution. For example, there are many of what we call ‘sustainable drainage solutions’ up and down the country, which soak rainwater away and slow it down, so it doesn’t all get to the sewer at the same time. This can help reduce the number of CSO spills. These can include specially designed ponds, lakes, grassy areas and rainwater gardens. They can enhance local communities, provide havens for wildlife and, when they’re installed in schools, are fun ways to teach children about the water cycle.
Each of us is responsible for looking after the sewer network. Each of the 12 water operators in the UK have creative campaigns to inform customers about, for example, the importance of only flushing toilet paper, pee and poo down the loo and of not putting fats, oils and greases down sinks to prevent sewer blockages.
Operators also recognise that it’s vital that they work in partnership with local authorities, regulators, customer groups, environmental charities, land owners and community partners.
With all this in mind, Water UK, the water industry trade association, has set up a programme board to review current practices and set out what research, engineering design changes, new regulatory controls and government policies we need to ensure that our drainage systems are fit for the future. This group of diverse partners includes environmental groups, engineers, regulators, government representatives, customer representatives, water companies and local authorities.
Together, we believe we can deliver affordable changes to our drainage systems, ready to meet challenges we face, now and in the future. We are working on research that will give companies the tools they need to plan the capacity of drainage systems and what we will need to do to in order to make them resilient. We have already had significant success with a clear message about wet wipes. It is early days, and a new way of working for us, but we are confident that it will deliver results to support our communities, the environment and the economy.
By Sarah Mukherjee, Director of Environment, Water UK
Read more: Water MattersAuthor : EurEau