Over the past few weeks, Britain has faced a deluge causing rivers to rise, and instigating more than 100 flood warnings, with particular risk in the south west of England. This exceptional weather event has already claimed several lives.
Meanwhile, across the Atlantic, FreshWater Watch studies in New York are looking beyond the more obvious dangers of flooding, and exploring the health risks carried by contact with urban flood water.
FreshWater Watchers are looking at the effects of sewerage storm overflows. Normally, rainfall from heavy rainfall is channelled into a combined sewer system - which collects sanitary sewage and storm water runoff in a single pipe - and is treated before being discharged into local waters. However when there are excessive quantities of storm water, the sewer overflows, releasing untreated waste water and storm water into nearby water bodies.
Concentrations of harmful bacteria have been shown to increase dramatically following storm events, as found in previous research carried out in the Netherlands.
A recent study (1) illustrated how in 2011 and 2012, samples were taken of urban floods and analysed for certain pathogens – that is any bacteria that can cause disease. The scientists found that urban floodwater was contaminated by faeces which contained harmful pathogens.
They concluded that if an individual drank 1 ml of water, the risk of infection was twenty per cent for floodwater originating from combined sewers, compared to ten per cent for floodwater originating from storm sewers alone and just one per cent for floodwater originating from surface runoff of rainfall.
A study (2) published prior to this explored the risk to human health from flooding brought about by extended rainfall. It determined the probabilities of obtaining infections as a result of contact with urban flood water, and found the health risk to be higher than that of swimming in recreational freshwater environments.
The results of these studies make a strong case for further research and data collection into the health risks brought by flooding.