Drain blockages in London are an all too common occurrence, as the city’s Victorian sewer system struggles with the pressure put on it by modern life.

When the Victorians built the London sewer network, they were not to envisage the population boom the city has seen over recent decades. And although the system has done well coping so far, there is still far too much sewage dumped into the River Thames at times of heavy rainfall.

Currently only around 2mm of rainfall can trigger a discharge into the River Thames from one of the 57 sewer overflows on the river. When the Thames Tunnel is built it will take the discharge from the 34 most polluting sewer overflows and transfer it to Beckton Sewage Treatment Works where it will be processed.

Thames Water say that on average a discharge is released around 50 times every year and a total of 39 million tonnes of sewage is released into the river. If the proposed tunnel build does not go ahead the forecast for annual sewage release is expected to increase to around 70 million tonnes, which could have a huge impact on the river and its wildlife.

Thames Tunnel project manager Malcolm Orford is giving a talk on the 13th of December about the current round of tunnel proposals put forward by Thames Water.

The free talk, which will be held at The Pier House in Chiswick at 7:30pm, will give people a chance to hear the latest information about the sewer project.

Currently over 39 million tonnes of sewage flow into the River Thames every year at times of heavy rainfall, as the city’s Victorian sewer system struggles to cope during times of heavy rainfall.

The plan is to capture overflow sewage from the 34 most polluting sewage outlets into the Thames and transfer it via the new ‘super sewer’ to Beckton Sewage Works where the waste will be treated.

The talk has been organised by Chiswick Pier Trust (CPT) who are a charity whose objective is to protect the River Thames and waterside areas. There will be time for questions factored into schedule and doors will open at 7:00pm.

A collapsed sewer in Welling has led to the death of around 1,000 fish in a stream in Danson Park, Bexleyheath.

Bexley council were called by concerned members of the public at the end of November after dead fish were noticed in the stream leading to Damson Park Lake.

After an investigation Thames Water found that sewage had found its way into the stream after a sewer in Welling collapsed. Officers from the Environment Agency were called to the scene, where a film of sewage fungus covered the bed of water.

Jonathan Taylor, the area base controller from the Environment Agency said:

“This is a serious incident and our officers have been on site over the weekend placing booms to stop the spread of the pollution.

“The Environment Agency will continue to oversee the clean-up of the incident with Bexley Council and Thames Water. The investigation is ongoing and we have no further details at this stage.”

A spokesperson for Thames Water stated:

“We got to the lake as quickly as possible to reduce the impact, and have been working with the Environment Agency to clean up the stream and pump air back into it.

“Any incident that harms wildlife is deeply regrettable.”

Drain maintenance engineers might be using less conventional methods to find leaking sewers in the future. Scientists in Montreal, Canada, have been working on a system which monitors how much caffeine is in a river or a stream.

The University of Montreal lead researcher Professor Sébastien Sauvé says ‘Cows don’t drink coffee’, so any water which contains caffeine, that is found in a brook or a stream must have a human origin. The findings show that watercourses can be tested for caffeine, and the more caffeine found, the more polluted the water is.

Mr Sauvé further commented:

“E.coli bacteria is commonly used to evaluate and regulate the levels of fecal pollution of our water from storm water discharge.

“But because storm sewers systems collect surface run-off, non-human sources can contribute significantly to the levels that are observed.”

The University team took around 120 water samples from around the city, which they analysed for traces of caffeine. And because there was a strong correlation between the level of bacteria in the water and caffeine levels in the water this method of testing could be used as an indicator of pollution due to faulty sewage systems.

Thames Water has just opened a new ‘black water’ sewage treatment plant which will provide non-drinkable water to irrigate gardens and lawns at the London 2012 Olympic park.

The new Old Ford facility was opened by the Secretary of State for the Environment, Food and Rural Affairs, Caroline Spelman and is the biggest works of its kind in Britain.

The £7m facility takes waste water from the Northern Outfall sewer and produces around 570,000 litres of recycled water every day.

The recycled water will also be used to flush toilets at the games site and will make sure the Olympic Delivery Authority exceeds their target of 40% water-efficiency.

Caroline Spelman stated:

“Despite our reputation as a rainy country, we may face a future with less rainfall and less certainty about when that rain will fall. If we want to make sure we have a reliable supply of water in the future we all need to play our part now. Projects like this, which safely recycle water and prevent the need for fresh water to be used where it isn’t needed, have a crucial role to play. Next month, we will set out our plans to ensure there is safe and secure water supply in the future.”