Clean water can be defined in many ways.  Is it visually clean?  Is it free from bacteria or viruses?  Is there chemical contamination?  If it has chemical contamination is it inorganic chemicals (ioc) that are naturally occurring such as from Fluorides, Arsenic, etc. or from introduced volatile organic chemicals (voc;s) with petro chemicals being the most common.

Only biological contamination will be dealt with in this website and that includes only bacteria and viruses that affect the human body.  These biologicals will have an immediate adverse effect on health and can cause death in just a few days.  Making the water potable is relatively easy using various filters that are inexpensive and easily maintained by the local population.  Many of the inorganic naturally occurring chemicals can be processed by the human body and depending on the concentration may have long term effects.  Dissolved organic and inorganic chemicals are also very difficult and expensive to remove from the water and can have deleterious effects on the population.  The equipment to remove the voc’s and ioc’s are elaborate and difficult to maintain.  There is a product that has been introduced by Sawyer that can cleanse small quantities of water of both voc;s and ioc’s.  They are individual filters and are expensive.