Raw sewage has been dumped into Welsh waterways more than 100,000 times in just 12 months.
Data from Welsh Water records the amount of times sewage has been released into Welsh rivers and streams to relieve pressure on the sewage network.
Part of this problem comes from the fact we have a combined sewer network. According to Welsh Water, when the sewer system is operating normally, combined sewers collect rain water that runs off gutters, drains and roads, as well as sewage. This wastewater is taken to treatment works, where it is cleaned, treated and returned safely to the environment through watercourses or the sea.
However, during heavy rain storms, more water enters the pipes than they are designed to cope with so there is an inbuilt design to relieve pressure on the system called "combined storm overflows" or CSOs which puts the sewage straight into Welsh rivers. Welsh Water say that without these release points, the sewerage system would back up causing sewage to flood out in buildings, streets, highways and to come up through toilets inside people's homes. However this has a huge environmental impact.
You can see the places in Wales which had the most releases in 2020 here*:
The map below shows some of the locations. Bear in mind that the points will not be the exact locations but approximations.
Why is this happening?
Welsh Water control more 36,000 kilometres of sewers that take your dirty water away before its cleaned at local treatment works and the clean water released into rivers and seas. Unfortunately, most of this network was built over 100 years ago during the Victoria era. Estimates suggest it would cost between £9 billion and £14 billion to remove CSOs completely from the network and would take decades. Welsh Water say it would make water and sewerage bills unaffordable.
Though it is obvious how the sewers get overwhelmed during heavy rain and storms, it begs the question when there are so many releases when during dry weather. According to Welsh Water, this is mainly due to blockages caused by flushing objects like nappies and wet wipes. These cause blockages which in turn case a backlog that is then released into rivers before it can go into homes.
It is worth noting that there is no "eject button" that anyone presses to release this wastewater. It is an automatic release built into the system when it reaches a certain pressure.
What does this mean for the environment?
In 2019 WalesOnline conducted an investigation into pollution in Welsh rivers. River users from different parts of Wales have been contacting us to about how the issue seems to be getting worse.
Fish Legal, a not-for-profit organisation fighting against river pollution, is advising the Mond Angling Society and Pontardawe and Swansea Angling Society in connection with ongoing sewage pollution downstream of Dwr Cymru’s Trebanos Waste Water Treatment Works on the River Tawe.
Data published by Natural Resources Wales for 2020 show that ‘storm’ sewage was released for over 3676 hours on 270 separate occasions - the equivalent of over 21 weeks of continuous discharges of untreated sewage into the river.
This image of a net shows a close up of algae build-up on a net after one day submerged in the river when Pontardawe and Swansea Angling Society assisted Swansea University during a sea trout, smolt tagging and tracking project.
Geoff Hardy, Fish Legal solicitor advising the angling clubs, said: “The water company’s facility appears to be unable to properly treat sewage in wet weather and also discharges in dry weather conditions.
"Despite being aware of the problem, Natural Resources Wales made only minor variations to the discharge permit in 2018 which allows ‘storm’ sewage to continue polluting one of the few fisheries in South Wales that offers the opportunity for disabled anglers to fish for salmon.”
Recently anglers in the area identified several fish covered in fungus Saprolegnia fungus infection which can be an indicator of poor water quality. Surveys in that area have also found increased in concentrations of E. coli which can also be an indicator of untreated sewage discharges.
Where in Wales has the highest rates of sewage being dumped in rivers?
These are the areas with the highest rates in different part of Wales (the full tables are at the bottom of this article).
Mid Wales
South West Wales
Valleys and South East Wales
North West Wales
North East Wales
Is this happening more?
This is a hard question to answer. Wales sewers are under more strain than ever for a whole host of reasons.
Climate change is making storms more common and severe which obviously adds pressure. But there are also challenges from people concreting their gardens. This leaves less soil to absorb rain water which means more runs into sewers. One person trying to tackle the issue in Welsh Water said that the increase in astroturf or "fake grass" was pushing more rainwater into drains.
But the big reason it is hard to establish if this issue is getting worse is the data. Natural Resources Wales, the regulator, required water companies in Wales to install monitors on storm overflows to record storm spills, these are referred to as Event and Duration Monitors (EDM). The work to install the monitors completed in March 2020 meaning that we now know how often this is happening but can't compare against previous years. The graph below shows how the amount of releases' of sewage water has increased fairly proportionally to the amount of EDMs.
So it looks like there are loads more releases but it isn't clear how much of this is just further monitoring.
You can view every Welsh Water release here.
A spokesman for Welsh Water said: “The network we have inherited is a combined one, it takes rainfall from roads, yards and roofs as well as sewage from homes and businesses. It therefore includes combined storm overflows (CSOs) which play an essential role in stopping sewage from backing up into customers’ properties during periods of heavy rain. They usually release storm waters into rivers or the sea and their operation is highly regulated and closely monitored by our regulator Natural Resources Wales.
“Whilst our CSOs are mainly operating as designed and permitted, we recognise that with environmental legislation tightening and customer expectations changing, more needs to be done.
“That is why we have invested over £8 million installing spill monitors on our CSOs and we will have monitors on all our CSOs where is it practicable to do so by the end of 2022. Monitoring now covers over 99% of our CSOs and all available data is published on our website for people to access at any time. Improving the monitoring is key to identifying issues, developing solutions and prioritising investment. This approach has been agreed with our regulators.
“As our profits don’t go to shareholders but instead are reinvested to improve our services, over the past 20 years we have invested over £1billion in our entire wastewater network. We have plans to invest even more and between now and 2025 will be investing over £800 million on further improvements to our wastewater system – which includes a £100 million programme agreed with NRW – to target our CSOs”. The most sustainable way to tackle these overflows is to remove surface water from the sewer, separating it from the sewage and returning it to rivers and seas, but to do this we need to work with customers and local authorities to intercept that water from roofs and yards and from highway drains before it gets into the sewer network and we are committed to working with communities to make this happen”.
*This is just data from Welsh Water and does not include any from the company Hafren Dyfrdwy
