Rainwater harvesting is one of those simple concepts that reminds us of old-fashioned sensibilities. Basically, it entails the collection of the rainwater that falls onto a roof, the storage of that water and its utilisation for domestic purposes.
The water is collected by normal roof gutters then passed through a filter to remove dirt, leaves and other debris picked up from the roof, gutters or down pipes. The filtered water passes into a storage tank.
Filtering is an important part of the process as any decaying organic material that remains in the water will consume oxygen through microbial action possibly making the water putrid. The storage tank should be sized to ensure occasional overflow. This will have the effect of skimming floating organic material from the surface of the water. Heavy particles will fall to the bottom of the tank where they will form a negligible layer.
Water is pumped from the tank by means of a submersible pump with a floating filter, thereby drawing the cleanest water from just beneath the surface of the water.
A mains water connection is also necessary to provide a top-up as and when required.
The harvested water can be put to many purposes. Through filtration it is particle free and is suitable for most domestic applications ~ toilet flushing, clothes washing and garden usage. Under certain circumstances it may also be suitable for human consumption although the water will require analysis and further filtration, pH correction or UV sterilisation may be required.
System maintenance is minimal, the filter will need to be cleaned 4-6 times a year. More complex systems that utilise pH balancing or UV systems will need additional maintenance.