Demographics, practices and water quality from domestic potable rainwater harvesting systems

In semi-arid regions experiencing rapid population growth, rainwater harvesting is becoming increasingly important. Roof-collected rainwater is the exclusive water source for many households worldwide. Improper collection, storage or treatment of rainwater can result in adverse health effects. This study surveys rainwater harvesting practices and examines water quality from these systems. At 36 households, stored ‘pre-filtration’ rainwater and ‘post-filtration’ water from the kitchen faucet used for drinking and cooking were sampled. Rainwater harvesters desire to conserve water and believe that rainwater is more healthful than surface or groundwater. Almost 95% of homeowners use filtration and purification devices, but 64% have never tested their water. Coliform bacteria were not found in any post-filtration water, but some pre-filtration water samples were high in total heterotrophic bacteria. Lead levels exceeded the United States Environmental Protection Agency (USEPA) standard of 15 μg L^−–1 in 25% of pre-filtration samples and 6% of post-filtration samples. First-flush diversion devices significantly decreased the likelihood of pre-filtration lead levels above 15 μg L⁻¹. Aluminium, copper and iron exceeded USEPA recommended levels in a small percentage of homes. Although water from roof-collected rainwater harvesting systems was generally within drinking water standards, regular testing should be encouraged to avoid potential health problems.