Why are sewage discharges such a problem in the UK?

To establish the extent of England’s problem with sewage discharges, we can compare the health of English waterways to others in the United Kingdom and to those in Europe. From there, understanding that England’s rivers are particularly ill and that sewage discharges are a significant factor in this ill health, we can begin to understand why these discharges are such a particular problem. 

How sewage discharges are ruining English waterways 

According to The Rivers Trust’s The State of Our Rivers report in 2024, England’s rivers are in critical condition, with zero whole rivers achieving high or good ecological status. Approximately 15% of river stretches meet at least a 'good' status, leaving a staggering 85% below this benchmark. Within these, 23% are rated as poor or even bad, a crisis compounded by pollution from multiple sources. By the UK government’s most recent reckoning in 2023, 16% of assessed surface water in England qualified as ‘good’, which includes 14% of rivers, 14% of lakes, 19% of estuaries, and 45% of coastal waters. Another study by the UK’s Environment Agency of bathing water quality, which includes many stretches of rivers, states that out of 423 bathing waters, 405 (95.7%) met the minimum standard, of which 281 (66.4%) were Excellent, leaving 18 (4.3%) below the minimum standard as Poor.

By comparison, the Scottish Environment Protection Agency (SEPA) published its Water Environment Summary Report in 2023, which detailed how 64.85% of assessed surface waters were considered as having ‘good’ ecological health, which includes 57.2% of rivers, 69.8% of lochs, 87.5% of estuaries and 99.6% of coastal waters. That’s an improvement of almost 50% (48.85%) over England. In Wales over the same time period, the total for surface water in good health is 40%, including 44% of rivers, 17.5% of lakes, 25% of estuaries and 43.5% of coastal waters. According to the Water Information System for Europe (WISE) in 2024, 37% of surface waters across Europe qualify as good. Similarly, the European Environment Agency determined in 2020 that 95% of bathing waters across Europe meet the minimum standards, of which 85% were excellent (or 18.6% above England), with only 1.4% below the minimum standard as Poor (or 2.9% lower than England).

So, what’s causing all of the damage in English rivers? In its report, The Rivers Trust determined however many causes of ill health for a given river stretch and then, adds these up to produce a set of percentages – but these percentages don’t add up to 100% because, for instance, a given river’s damage is caused by agriculture, the water industry and urbanisation, so that this river is counted three times. The figures are:  

• Agriculture and land management: 62%. 

• Water industry: 54%. 

• Urbanisation: 26%. 

More specifically, continuous sewage discharge or intermittent sewage discharge are at least one cause of a river’s ill health in 35% and 11% of cases, respectively. A recent study from the University of Oxford using its own bespoke methodology determined that when considered in its interaction with seasonal changes in river functioning, sewage pollution was the leading cause in the disruption of river ecology. Nevertheless, by either reckoning, England’s relatively poor river health is significantly determined by sewage discharges. 

Sewer Infrastructure: Too Small for the Task?

England’s sewer network is aging and struggling to handle rising demands, especially during storm events. Unlike some countries that use separate systems for sewage and stormwater, much of England’s infrastructure follows a combined sewer system, where stormwater and sewage are collected together. During heavy rainfall, combined sewer overflows (CSOs) are triggered, releasing untreated sewage to prevent sewer backups. This reliance on CSOs has become a focal point of the sewage discharge debate, as they discharge pollutants directly into waterways.

Compared to other countries, the UK’s sewer infrastructure is comparatively small. For example:

• United States: 1.2-1.5 million km of sewers for a much larger population and area.
• Germany: 600,000 km serving a population of 83 million.
• France: 400,000 km for a similar population size to the UK.

This dense, aging network faces enormous strain as it serves urbanized areas with significant impermeable surfaces, exacerbating stormwater surges and demanding continuous management of both sewage and storm runoff.

Impacts of Sewage on River Health, Public Health, and the Economy

Unchecked sewage discharge affects ecosystems by introducing harmful nutrients, pathogens, and toxic contaminants. Excessive nutrients lead to algal blooms, which deplete oxygen and create dead zones where aquatic life cannot survive. Human health is also at risk, as polluted rivers and coastal waters expose populations to pathogens and potentially harmful chemicals. The economic repercussions are also profound, as tourism, fishing, and even drinking water sources are impacted by poor water quality.

The Need for Innovative and Natural Water Management Solutions

Expanding sewer capacity is a costly and essential goal, but increasing infrastructure investment alone may not fully address the growing problem. England must adopt sustainable, decentralized solutions such as artificial wetlands, rain gardens, and retention ponds. These ‘living machines’ not only support stormwater absorption but also treat wastewater by filtering pollutants naturally, reducing the volume of water entering the sewer system and lowering overflow risks.

Increased use of rainwater harvesting and green infrastructure within urban areas can alleviate the burden on existing systems, while restoring floodplains and soil quality can mitigate runoff. Improving soil management and nutrient management in agriculture would also be crucial to reducing pollution at the source, helping keep rivers clean and ecosystems resilient.

Financial and Regulatory Challenges

Decades of underinvestment, coupled with recent funding cuts to the Environment Agency, have further compounded England’s water crisis. To tackle sewage discharges effectively, significant financial and regulatory support is essential. The cost of modernizing and expanding sewer systems is steep, but the long-term environmental and health benefits make it a vital investment. Additionally, enforcing stricter standards on both agricultural practices and industrial discharges will be necessary to hold all sectors accountable for their impact on water quality.