Water and flooding

Environmental design must work with water rather than against it. Water-efficient appliances, rainwater harvesting systems and grey water recycling will eventually become embedded in building design. Flooding is likely to affect more people in a changing climate,3 particularly near coastal areas and rivers and in the south of the United Kingdom, where the landmass is slowly sinking. Developments should only be built in areas of low flood risk. Flood-resilient buildings are ‘wet-proofed’, designed with future flooding in mind. CO₂ reductions are dependent on the rainwater system used, how much rainwater can be collected versus the amount needed and how much pumping is required to get the rainwater to the place of reuse. For landscape irrigation, install a simple rainwater butt without pumps. Runoff or drainage coefficients are affected by the rainwater collection surface and how much water is lost, evaporated or absorbed. Rainwater tanks are normally sized to store 5% of the yearly collected rainfall.