Roof collection and storage of rainwater for drinking

Collecting rainwater from house roofs can provide both a reliable supply and one that complies with World Health Organisation drinking water guidelines. Mass balance allowance allows the storage volume to be assessed. Pathogen die-off in accordance with first order kinetics shows that two or more tanks operating in series will remove substantially more pathogens than a single tank of the same capacity. Drop inlet pipe, bottom overflow and a floating arm draw-off can provide the quiescent conditions for Cryptosporidium oocysts to settle and achieve drinking water protozoa compliance without microfiltration or ozone disinfection.