The river now faces discharges of untreated sewage on a weekly basis. In the summer months when the river flow is at its lowest, a single discharge event can equal the river's flow in one day, which can be catastrophic for the river environment as was the case in August 2004. It also presents a highly variable hazard to the health of all river users, who are suffering from continual exposure to high levels of pathogens. Rowers Against Thames Sewage maintain a website to provide up-to-date information to the river sports community, but are not supplied with any timely information from Thames Water or the Environment Agency and have to rely on first-hand experience to report on the effects of major sewage discharges.

Thames Water blame the Victorian sewer system of Combined Sewage Overflows (CSOs), however, the discharge figures supplied by the Environment Agency show clearly that over half the problem is due to discharges directly from the sewage treatment works (STWs). Since 1991 the three major STWs processing London's sewage have been under capacity and in breach of the EU Urban Waste & Water Treatment (UWWT) directive. There has been no enforcement by the Secretary of State or OFWAT, to ensure that Thames Water provide adequate sewage processing under the 1991 Water Industry Act. The inadequate processing capacity and 'storm' storage at Mogden STW results in regular discharges to the Upper Thames Tideway below Richmond Lock after practically every minor rainstorm. For the upper tideway this is the principle cause of pollution and hazard to health as there are no CSOs upstream of Hammersmith. In addition all the 'clean water' discharges into the river of processed sewage from the plants still contain high levels of pathogens (such as Salmonella, Cryptosporidium, Giardia, Norovirus, Cholera) as there are no systems in place for removing pathogens from the sewage water.

DEFRA promised in their 2002 booklet 'Directing the flow, UWWT' (page 64): “By the end of 2005 we expect secondary treatment to be the minimum standard of treatment for almost all treatment works serving over 2,000 people.” – None of London's main STWs comply with the UWWT which demands secondary treatment as a minimum requirement for all sewage, nor are they likely to do so for many years.
There are also a couple of other points that have come to light recently regarding the Thames Tideway Strategic Study (TTSS). Firstly, I have had it confirmed by the TTSS that they elected not to include discharges from sewage treatment works (including their 'storm' storage tanks) in their study and conclusions, despite stating in the same report that they are the dominant factor in polluting the Thames tideway; and secondly, the Environment Agency have confirmed that the figure they quoted: 20 million cubic metres for the total discharge of untreated 'storm' sewage into the Thames annually, has turned out to be sadly under-estimated. They recently revealed that an estimated 57.4 million cubic metres of untreated sewage was discharged into the river in 2004 and this was just a little more than the previous year, but it indicates that the true scale of the problem has increased dramatically in the four years since the beginning of the £4million TTSS study.

We believe this places doubts on the ability of the proposed Storage Tunnel scheme to be the solution it claims to be, especially as there is no proposal to connect Mogden STW to the tunnel, even though Mogden desperately needs the extra storage and affects the river most when it discharges untreated waste. It also places severe doubts on whether the current plans for upgrading Mogden STW are sufficient - a schedule of works only agreed upon at the end of last year which are not due to be finished until 2012, and have been in planning for over four years. Clearly the CSOs are a problem, but one that should be addressed at source (i.e. where rainwater enters the sewers). Rainwater catchment schemes must ultimately be the answer that could also provide the additional benefit for drinking water supplies, rather than creating a bigger problem in the drains.

Our suggestions for solving London's sewage crisis involves a common sense vision to encompass London's needs for both sewage and drinking water:

Thames Water initial statement
in response to RATS findings:

"The Corporation of London Port Health Authority provides advice for river users, and gives a phone number for them to call. When giving this advice they take into account discharges from the sewer system and treatment works.

"The Urban Waste Water Treatment Directive (UWWTD) is European legislation that is enforced by the Environment Agency (EA) in this country. The EA sets standards based on the Directive for us to adhere to. Discharges to the Thames Tideway are permitted by our operating licence, and we are meeting the standards set for us by the EA. We are not, as RATS claim, in breach of the UWWTD.

"Discharges to the Thames take place from both combined sewer overflows and sewage treatment works. The tunnel proposed by the Thames Tideway Study Group (comprising Thames Water, the EA, Defra and the Greater London Assembly) would tackle discharges made to the river - but only from combined sewer overflows. The current situation is not sustainable in the long term, and we're ready, willing and able to plan, design and build the tunnel - but need Government authority to proceed, and are still awaiting their decision. A solution of this sort was first proposed by Thames Water over 15 years ago - but has been put on hold by successive governments.

"Our regulator Ofwat has recently approved our plans for a nine-year, £400m programme of work at Mogden, Beckton and Crossness, the three large sewage works on the tidal Thames. We will increase the capacity of the works, significantly reducing the size and frequency of discharges to the river, and improving river water quality as a result.

"The feasibility of a separate surface water drainage system, which RATS propose, was examined by the Thames Tideway study group - and found to be impossible. The installation of a separate set of pipes throughout the parts of London where the sewer system currently receives both waste and rain water would be massively disruptive and prohibitively expensive.
"Despite the discharges, the Thames is home to a rich ecosystem, including more than 120 species of fish. We've invested £1bn to improve the quality of sewage treatment in our region since privatisation in 1989, which has helped improve the quality of river water."

5 Sept.05

Thames Water statement from Tom Kelly, Head of Wastewater Operations in response to RATS findings:

The question of how to modernise London’s sewers to meet the demands of the 21st century raises huge challenges. Victorian engineer Sir Joseph Bazalgette designed and built a system to handle the city’s sewage, but only a limited amount of rainfall. The capital has a ‘combined’ system, which collects both rainfall from roofs and road gullies, and wastewater from domestic and commercial properties. This means that intense rainfall can quickly and significantly increase the levels in the sewer network, which was designed with overflow points to allow water to escape into the River Thames once the system nears capacity. These ‘safety valves’ prevent widespread flooding of homes and businesses across London. Regrettably, they also mean that dilute sewage sometimes enters the river during heavy rainfall. Storms can also lead to occasional discharges from London’s three major treatment works (Mogden, Beckton and Crossness).

Although less than five per cent of all rainwater and sewage entering London’s sewers is discharged without any treatment, these occurrences are both unpleasant and unsightly. They also mask the significant improvements we have helped bring about in the river. Biologically dead only decades ago, it is now home to a rich and diverse ecosystem. We have invested £1bn since privatisation to ensure the capital’s sewage is treated to an exceptionally high standard. The most recent figures show that, under normal weather conditions, our works achieve 99.9% compliance with the Environment Agency’s stringent consent requirements. Treatment standards are particularly tight during summer months, to ensure a high quality of effluent is discharged when the river level is low.

Storm sewage discharges occur with the consent of the Agency, and are permitted by our operating licence – but we accept the need to make improvements in the long term. We have played a central role in the Thames Tideway Strategy Steering Group, which has assessed the environmental impact of the discharges and investigated potential solutions.

Rowers Against Thames Sewage (RATS) suggest that surface and foul water drainage should be separated. This was examined and rejected by the Steering Group, which found it to be both prohibitively expensive - at a cost of around £12 billion - and impractical. New developments are constructed with separate drainage systems, but 12,000 km of new sewers would be needed to segregate the existing combined system, and Londoners would not thank us for digging up much of the capital.

The Steering Group favours a 35km storage and transfer tunnel, which would considerably reduce the need for discharges by taking sewage to Thames Water’s Crossness works for treatment. It would require a minimum of five years to plan and acquire the necessary land, and around ten years to build, at a cost of approximately £1.7 billion. We are ready, willing and able to build the proposed tunnel, but before we can begin work we need the Government to approve the project and our regulators to agree its funding.

While the tunnel would address combined sewer overflows, we are reducing discharges from our sewage treatment works separately. Ofwat has recently approved our plans for a £400m, nine-year programme of work to increase the capacity of our Mogden, Beckton and Crossness works, greatly reducing the size and frequency of storm sewage discharges. In addition, improvements to treatment standards at the Beckton, Crossness, Long Reach and Riverside works will significantly improve effluent quality during summer months, when the Thames is at its lowest level. These improvements will together reduce by 87% the number of times the amount of oxygen in the river falls to a level critical for fish survival. In the meantime we use a number of short-term measures to minimise the impact of storm discharges. These include releasing hydrogenperoxide into the river, and pumping in oxygen from specially-designed barges, to boost water quality. We have also greatly reduced the amount of sewage litter entering the river during storms by installing screens at Abbey Mills pumping station in east London.

Work is underway to provide two boats that will remove surface litter from the river after discharges take place, reducing the aesthetic impact of the pollution. They are due to come into operation in the latter part of next year.

RATS argue that these improvements should be enforced by regulations. No-one should be in any doubt about the level of scrutiny to which we are subjected by Ofwat, which ensures we fulfill the commitments agreed with them in our business plans.

We are proud of the part we have played in improving the quality of the Thames, and confident the work we are planning will benefit the river for decades to come.

Tom Kelly, Head of Wastewater Operations at Thames Water.
20 Sept. 2005