Smart water tanks
Computer-controlled containers to slow the flow
Roofs are amazing resources for many reasons, one of which is that they are superb rain-harvesting devices. In effect, they act as big funnels and direct the rainfall into your gutters, and then often straight down your drain. Each average terraced roof in Britain receives between 10,000 and 70,000 litres of rain a year. Imagine a housing estate, then flatten out all those roofs into one big area – that is a lot of water potentially contributing its volume to a combined sewerage system during a heavy storm and ending up as diluted raw sewage entering your local river via a CSO.
‘Disconnecting your roof’ by collecting that rain in a water tank is a good idea. To be effective though, there has to be room in the tank for a coming storm. If the tank is full, it can’t prevent the storm water hitting the drainage system. One method would be to manually empty out some water when there is a storm forecast. Another more sophisticated method is to have a water tank with a computer that receives weather forecast data, so water can automatically be released when a storm is forecast.
More sophisticated still would be entire residential areas with water tanks receiving data. These could be ‘micromanaged’ to enable localised storm-water management and optimise the harvested water made available for other tasks, such as flushing toilets and watering the garden.
The technology is there, the questions, as always, are largely financial: who pays who and how, and who pays to install and maintain the equipment?
Trials are underway. South West Water has installed smart water tanks in the village of Combe Martin in Devon. Early results show that during the first six months residents stored a total of 122,000 litres of water in the 35 tanks, which would have required 245 tanks without smart controls.