The “toilet bung” – a rubber bag pushed round the U-bend and inflated with a bike pump – is among the more unusual flood protection products Andy Tagg has encountered at the HR Wallingford testing laboratory in Oxfordshire. As those who have been flooded know to their cost, sewage is frequently part of the filthy water that invades submerged homes.
Tagg, who manages the lab, says protecting homes is increasingly important because unpredictable flash flooding, which can strike far from rivers or coasts, is becoming a bigger threat. Three million homes are at riskin the UK and the number is rising because global warming is intensifying downpours. “Hundreds of thousands of houses are going to have to get these measures just to cope with climate change,” he says.
The technology has moved far beyond sandbags in recent years, he says, with flood-resistant UPVC front doors now on the market and superseding slot-in barriers. “There was a stigma about having visible measures as people didn’t want potential buyers to know that there was a flood risk,” Tagg says. “But you do have to think about where the letterbox goes.”
“Intelligent” air bricks are another innovation Tagg has tested. Balls float upwards as water levels rise, blocking off the ventilation holes. Waterproof renders are available to stop water seeping through the mortar between bricks. Tagg says there is interest in freestanding barriers which, filled with soil or water and pegged down, can protect a group of homes.
Another approach is to slow down water runoff with grass roofs, porous paving on driveways and even simple water butts. “It is all about slowing down the flow of water,” says Hannah Cloke, a flood defence expert at the University of Reading. “Even if it is just your house, there will still be a direct benefit to you in reducing the risk from surface water flooding.”
But she says it often take the trauma of being flooded to spur people into action. “People who have been flooded tend to take things more seriously.”
The key, according to Pete Fox at the Environment Agency, is getting the right advice on what measures to fit. “People need have really good surveys done to get the right products fitted correctly.”