Question:
What method of water purification would you teach someone who lived in a third world country and had no clean?

3. What method of water purification would you teach someone who lived in a third world country and had no clean water to drink? Why?

Answer: Most of these answer are totally unrealistic. No chlorine, no iodine, not enough fuel available to boil the water, no money for PUR or any other carbon filters, activated carbon is particularly unavailable.

But it does depend on what's available. A reasonably cheap purification system could be made from a settling tank, a sand filter, pipes and water valves. A suitable engineer could design one quickly around such items if they are locally available.

Simplicity, durablity and available materials than can be replaced easily from local sources are essential. It is idiotic to used a computerised system for instance where power supplies are irregular.

Most water supplies in the "first world" were filtered but not chlorinated until about 100 years ago.

Filter the water through a thick layer of clean sand with a layer of crushed charcoal under it. Many microogranisms are associated with clay particles. The sand has to be cleaned or replaced frequently. Distribute terracotta filters made with sawdust mixed with the clay. On firing the sawdust burns out leaving a porous terracotta suitable for filtration.

Store the filtered water for 24 hours, covered, in a copper or brass container. The copper kills some bacteria etc.

Place the water in a clear plastic bottle and leave a couple of days in full sun. That kills some bacteria too.

There is no means of guaranteeing that water contains no harmful organisms, even in the "first world". All you can do is remove most of them and stop the remainder from growing.