Early-warning alarm to combat sewer flooding nightmares

Jun 24, 2011

Thames Water innovators have created an early-warning system for homes at risk of hideous sewer flooding.

The devices, which are triggered by air pressure, sound alarms if flows in the drains get too high, alerting householders so they can call Thames Water before vile effluent spills into their homes – a truly miserable experience.
In a four-month trial, 60 properties had alarms fitted and five blockages with the potential to have caused sewer flooding were cleared as a direct result of the alarms going off.
Dr Sarah McMath, Thames Water's head of planning, optimisation and innovation said:
"We have proven that the technology behind these alarms works, but they are still far from the finished article.
"The next step is to link the alarms directly to the Thames Water operations centre, so if householders are out or on holiday, we can tackle the problems for them - or they if are in, we'll be on our way before they even call us.
"Whether it's caused by sewer abuse or a lack of hydraulic capacity, we are committed to putting an end to this horrific experience – and our sewer alarm is part of making that happen. This is the 21st century. There is no place for sewer flooding. It is a truly horrible experience and we are determined to protect our customers from this misery.
"Typically, if a sewer blocks the first sign of a problem is an overflowing manhole or gulley. At this late stage, a flood has already occurred. Our household sewer alarms will give customers a crucial heads-up before the flood happens."
Thames Water takes away sewage from nearly 14m customers through 43,500 miles of pipes across London and the Thames Valley. Each year the company spends £12m clearing 55,000 blockages, caused mainly by sewer abuse – putting anything other than human waste or loo roll down drains.
According to the firm's 'Bin it – don't block it' campaign to combat sewer abuse, food fat is the biggest no-no of all. It might go down sinks easily enough when it is warm but once it hits sewers it cools and sets hard, sticking to non-flushable items and forming hideous 'fatberg' blockages, which can in some cases lead to sewage backing up into people's homes - around 1,000 a year in the Thames region.
Sewer flooding can also occur because some areas of the network have been overtaken by population growth and urbanisation preventing natural drainage, so the capacity of the sewers cannot handle all the flows, particularly after heavy rain.
Thames Water is spending £350m between 2010 and 2015 on schemes to protect at-risk properties from sewer flooding. The alarms involved in the test were fitted at properties that have experienced sewer flooding in the past across South London, West London, Oxford and Reading.
The gadget was a finalist in the ‘most innovative new technology of the year’ category of the 2011 Water Industry Achievement Awards.

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