If the situation arises where un-purified water must be drunk to avoid dehydration basic precautions can be taken to avoid illness.
- Remove any suspended particles and organic matter
- Let the water stand for at least an hour
- Remove the clear water without disturbing the sediment
- Pour through a coffee filter
- Repeat the process
- Drink in small amounts at a time
If in a rural or third world area with shops a markedly more efficient and quicker method of purifying water is to buy readily available aluminium sulphate or alum (sometimes known as pickling powder).
Add ¼ tsp per gallon of water, wait for 5 minutes stirring occasionally. A floc will settle on the bottom and the clear water above should be decanted ready for drinking