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Depending on the water source you will probably need a combination of filtration and chlorination to deal with bacterial contamination.

The filtration could be a simple gravity sand filter if you are looking for something for a community or a ceramic filter if you are providing treatment on a family level. If there is no organisation for the maintenance of public assets, I would suggest that you go to the family level.

A sand filter could be made out of in an oil drum filled with sand. Water would flow in at the top and be collected from the bottom. Part of the treatment comes from biological action by bacteria that develops in the top layer of sand (exposed to sunlight) and this would clog up periodically and have to be replaced.

Ceramic filters come in various shapes and sizes, sometimes with a twin bucket system with water flowing through the ceramic filters from the top to the bottom bucket. Simpler still are ceramic filters with a siphon tube. The dirty water is put in a bucket or pot at a higher level and flows to the siphon to the lower level container.

Chlorination may be necessary, though the filter should remove most of the bacteria. There are guidelines in several books that I have at home but unfortunately I am currently working in Namibia. They are probably in the RedR book "Engineering in Emergencies". It depends on the volume of water and the strength of the chlorine used. Water should be allowed to stand for a few hours after chlorination to allow the chlorine time to kill bacteria before it is drunk. As a rule of thumb, if you can taste the chlorine it is a slightly stronger solution than it needs to be.

Moving up a level, there are simple plants that combine filtration and chlorination. I have seen a British Army one some years ago on a RedR course. These, however, are likely to require a strong commitment to operation and maintenance.

Mineral contamination is much more complex and would depend on the precise contaminant involved. It is very expensive and technically difficult to remove dissolved minerals from water.

Regards, Martin