Number of spills ‘directly linked to wet weather’
WALES saw a huge increase in the sewage spills into rivers, lakes and seas from over-loaded drainage systems last year.
In total, untreated household waste poured into waterways for nearly a million hours in 2023, an increase of 68% on the year before.
New figures show that Dwr Cymru Welsh Water recorded a total 105,943 spills last year, lasting a total of 916,166 hours. Around 95% of these were described as “significant” outflows.
Welsh Water said this was due to 2023 being one of the wettest years on record, with more severe weather events linked to climate change. The figures come from storm overflow event duration monitors – tools that record how often, and for how long, storm overflows operate.
Most of the UK’S sewers are combined sewers, Welsh Water said, meaning rainwater and waste water are carried in the same pipes to sewage treatment works. During heavy rain when more rainwater enters these pipes, they overflow into rivers and seas to relieve pressure. Welsh Water says 95% of the amount released is surface water, with the sewage highly diluted by rain.
In addition the company recorded 3,253 emergency overflows lasting 30,563 hours. These happen mainly at pumping stations and other sites using power, which are designed to spill when there is a failure (for example electrical or mechanical failings, or a blockage). A further 7,683 were unpermitted overflows, which lasted 69,928 hours and relate to overflowing assets that don’t have permits and emergency overflows that act as storm overflows.
A Welsh Water spokesperson said: “We take our responsibility for protecting the environment seriously and understand the real concerns there are regarding storm overflows (SO). While water quality is impacted by a large number of factors, of which storm overflows play a small part, we do understand these concerns and assure our customers that this is something we are listening to them about.
“Since 2018, we have led the industry on the installation of monitors on storm overflows and always been open with this information by publishing it on our website and report the number of spills to our environmental regulators. We have also provided real-time spill information for key bathing waters to interested bodies, including Surfers Against Sewage and Rivers Trust.”
The spokesperson said the higher number of spills could be “directly linked” to wet weather, when overflows discharged to prevent waste water flooding. With 10 named storms and eight months of aboveaverage rainfall (which was at 200% in March, the wettest March for 40 years), NRW said Wales was seeing an increase in severe events linked to climate change.
Removing the overflows from the system would be “unaffordable and would take decades”, the spokesperson added.
Instead those with the biggest environmental impact are being improved, with £140m being invested from 2020 to 2025 and £420m from 2025 to 2030.
When the data is combined with smaller provider Hafren Dyfrdwy, Natural Resources Wales said a total of 107,842 spills lasting a total 932,396 hours happened in Wales in 2023, with a further 7,791 unpermitted spills lasting 70,289 hours.
Sian Williams, head of operations at NRW, said the regulator was “absolutely committed” to improving water quality for people and nature in rivers and coastal waters. She added: “We understand the concern of many across Wales that overflows are still operating too frequently, and we continue to push water companies to improve their performance and reduce spill numbers.
“This includes increasing our frontline capacity for water regulation and tightening the guidance for the conditions under which an overflow should spill. During the forthcoming investment period for water companies (2025-30), we have pushed for record levels of investment for the environment, targeting areas where their operations are causing the most harm.”
NRW says it tightened the permitted conditions for a storm overflow to spill in new guidance issued in October 2023.
Earlier this month, Welsh Water was ordered to pay £40m to customers after Ofwat found it had misled them, and regulators, over its performance on leakage and saving water. In February, a Senedd committee found the company wasn’t doing enough to deal with pollution, drinking water quality and supply interruptions.
In 2023 an investigation found NRW had recorded more than 200 breaches of regulations by Welsh Water over six years but the infringements only led to two fines.
Welsh Water’s spokesperson gave an example of how it aims to improve storm overflows, citing one in Pontypool: “Here we are investing over £12m to build a nature-based solution that will help reduce the number of spills and boost the water quality in the nearby Afon Lwyd and River Usk. The site is the first of its kind in Wales, and involves the creation of reed beds, wetlands, footpaths, environmental enhancements and educational areas, providing socio-environmental benefits for the community.”
In general the company said it had seen “real improvements” from investing in the wastewater system, but recognised that “with environmental legislation tightening and customer expectations changing” more needed to be done.
Equally as important as tackling storm overflows is tackling phosphorous pollution, the spokesperson continued, “and we are delivering a comprehensive programme of upgrades to our wastewater treatment works that will remove 90% of our phosphorous discharges by 2030. Last year we published our manifesto for rivers in Wales which outlines how we are investing in our wastewater network, particularly around rivers in special areas of conservation.”