Typical post-storm sewage discharge into a river system. Water companies are permitted to release sewage into rivers and streams when the existing sewer system’s capacity can’t cope, for example after extreme weather events such as prolonged heavy rain

Why is there even sewage discharge in our rivers?

Water utilities are permitted to release sewage into rivers and streams when the existing sewer system’s capacity can’t cope, for example after extreme weather events such as prolonged heavy rain. This protects properties from flooding and prevents sewage backing up into our streets, homes and roads. Indeed, the EA itself says that overflows are “not a sign that the system is faulty”, and that they are “a necessary part of the existing sewerage system”.

These “permitted releases” are closely monitored by the water companies themselves and are an accepted part of water regulations. The simple fact is that the UK’s sewer network is old, Victorian, coping with new housing developments, and a high level of sustained investment by the water companies is needed to modernise and maintain sewage networks. But, water companies are under competing pressure to keep consumer water bills low, as well as provide dividend payouts to shareholders, and some are already in a poor financial state. The argument goes that this uncomfortable set of contradictory priorities has caused decades of under-investment, leaving an aging system unable to cope.

Something is amiss!

And, something is amiss. According to the latest EA data published last year, every single English river failed to meet quality tests for pollution, while only 14 per cent achieved a “good ecological standard”. Rivers need to meet both good ecological and chemical standards to achieve the overall good designation. For this report, the EA assessed 4,600 rivers, lakes and other waterways and none was rated as good on both standards. The highest rating of both standards was moderate – relating to 3,740 waterways, with 793 judged poor and 137 rated bad.

This low river water quality nationwide is largely blamed on agricultural and industrial run-off into rivers, but also on pollution by raw sewage discharges from water companies. There were 403,171 such spills of sewage into England’s rivers and seas in 2020, totalling more than 3.1 million hours of spillages.

So, whilst water utilities are permitted to discharge sewage into rivers and streams after extreme weather events, campaigners argue the private companies are taking advantage of the rules and lax regulation. Pressure groups such as Windrush Against Sewage Pollution claim to have amassed evidence which shows locally there are far more sewage spills occurring than are being reported, with water companies taking advantage of a system in which they largely monitor themselves.

 

The Environment Agency and Ofwat investigate

In fact, the EA and the Water Services Regulation Authority (Ofwat) have launched a major investigation into sewage discharge, after new checks led to water companies admissions that they could be releasing unpermitted sewage discharges into rivers and watercourses. This will see an investigation involving more than 2000 sewage treatment works. Any company caught breaching their legal permits could face enforcement action, including fines and prosecutions. Fines can be up to 10% of annual turnover for civil cases, or unlimited in criminal proceedings.

“This will see an investigation involving more than 2000 sewage treatment works. Any company caught breaching their legal permits could face enforcement action, including fines and prosecutions. Fines can be up to 10% of annual turnover for civil cases, or unlimited in criminal proceedings”

In recent years the EA and Ofwat have been pushing water companies to improve their day-to-day performance and meet progressively higher standards to protect the environment. As part of this, the EA has been checking that water companies comply with requirements and has asked them to fit new monitors at sewage treatment works. This is to make sure the right levels of wastewater are being treated before overflows are allowed to enter the environment. Such new monitors already exist: tryptophan sensors.

What’s the solution for water companies?

The state of England’s rivers has drawn together a broad coalition of anglers, wild swimmers, boat-owners and neighbourhood groups – anyone, in fact, who uses the waterways for non-industrial purposes. Charities including the Rivers Trust and Surfers Against Sewage, pressure groups such as Blueprint for Water along with celebrities such as Bob Geldof and Gary Lineker, are among those calling for ministers to take tougher action to stop water companies discharging sewage into rivers. This public pressure isn’t about to go away.

For all parties concerned with water quality and sewage discharge, it is in their interest to use tools to detect and prevent sewage spills. Failure to invest in such tools will mean continuing fines for water companies, such as the £4m fine as recently as November 2021 for Thames water for a sewage discharge that killed 3,000 fish in an incident that sent a waterfall of raw sewage gushing into streams and through a pub garden. Up to 3,000 fish were killed by the discharge in July 2016, which ran for 3.5km, through a pub garden and past community allotments. It is the third major fine for Thames Water in 2021, following prosecutions for two other incidents which also took place in 2016. Thames Water was accused of failing to carry out essential maintenance in a sewer that was known to have problems with blockages. The EA said the incident was “foreseeable and avoidable” but the company had relied on members of the public noticing the sewage leak because “it had no system in place to identify it”. Such systems exist – the Chelsea Technologies Tryptophan sensor.

“The EA said the incident was “foreseeable and avoidable” but the company had relied on members of the public noticing the sewage leak because “it had no system in place to identify it”. Such systems exist – the Chelsea Technologies Tryptophan sensor”

For its part, Southern Water is taking action to tackle sewage pollution, with a £1.5 billion investment programme to reduce by 80 per cent all pollution incidents by 2025 and is setting up a task force which will work with local stakeholders to find innovative solutions to cut overflows. A spokesman said: “Public awareness of storm releases is growing and there are increasing calls for the highly regulated practice to end. We support these calls and have adopted a pioneering approach. While simply separating all sewers from surface drains would be a hugely expensive and disruptive process, we believe that a partnership approach is the best way forward. Regulation on sustainable drainage must be changed so rainwater separation is built into all new construction. Investment in natural capital, such as enhanced and expanded wetlands, will be key.”

How does a tryptophan sensor detect sewage?

Tryptophan is an essential amino acid produced by all living things, and our multiple tryptophan case studies demonstrate that in situ Tryptophan-like fluorescence monitoring, using the Chelsea Technologies’ tryptophan sensors, can identify sewage pollution events in complex and heavily contaminated river systems, discern different water ‘types’ and pollution, provide information about the activity of the microbial population present, which is influenced by nutrient pollution (ie agricultural runoff), identify low levels of FDOM in rivers with little-no human impact and be used in a range of environments for investigating the fluorescence properties of natural waters, which applies to both environments which are heavily impacted by nutrients and pollution, and those which are low-nutrient in nature with little to no impacts from human-induced pollution.

UviLux tryptophan sensors bundles

The compact design and low cost of the *LUX range of sensors make them ideal for mass deployments, and low power consumption coupled with a wide choice of data outputs and anti-biofouling options allows for long-term remote deployments. Integration to realtime data display systems for management of assets with alarms means instant readings, no need to take samples back to lab – immediate problem identification as they occur in realtime, saving stock and assets.