With recurring droughts and increasing interest in collecting rain water, I am beginning to look for guidelines on how to catch, clean, transport, store, and distribute rain water for other purposes. Wherever humans build homes, there are often hard or impervious surfaces that do not absorb water. When water runs from these surfaces it may exceed the capacity of surrounding soil to absorb readily. In those cases it becomes a problem. When we are able to capture some of this water and store it for later use, we may turn a potential problem into a potential asset.

Beware. Rainwater likely includes contaminants. In general, rainwater is of good quality for many purposes. Our collection and storage mechanisms may add contaminants, however. Water collected from hard surfaces may include dust, bird droppings, insects, and other detritus not suitable for human consumption. Rainwater may be very acid and have adverse effects on certain plumbing components. The materials that make up catchement and transfer systems may add contaminants. Without adequate filtering, rainwater may clog irrigation components. Without adequate screening, you may breed mosquitoes

Rainwater users are encouraged to think carefully about their end uses and to consider all aspects of that requirement whether it be for plant, animal, or human uses. At a minimum, Rainwater should be regarded as no better quality than any other surface water. Most of us would not drink from an open ditch. In some cases, we probably shouldn't allow our pets and livestock to drink from that ditch. And we can't assume that ditch water is suitable for irrigation. We need to pay attention to details.

In searching for information on cisterns, it quickly becomes obvious that they are a source of household water in many areas of the world. Their uses include laundry, bathing, washing dishes, flushing toilets, cooking, and even drinking. Some references below will include cisterns for such purposes. The goal of self-sufficiency is noble. Yet we must encourage users to follow established guidelines for safety. If water is to be used for human consumption, users must be responsible for insuring that the water is safe for its intended purpose. Remember that various users will have differing sensitivities to contaminants. Water is almost never pure and may contain a wide range of contaminants. Users must take all necessary steps to reduce risk of exposure to those contaminants that may cause hazards for human use. The link below to Evaluation of Rooftop Collection-Cistern Storage in Virginia provides a useful summary of some of the hazards and strategies for mititgation.

Primer on Rain Water Harvesting
by Al Cooke

The following links are provided primarily for those who seek supplementary water for irrigation. I hope they will help in your quest for more information about how to use rainwater safely.

Rain Water and Rain Harvesting