Ideal sources of water are fast flowing creeks and rivers which don't have large sources of pollution in their watershed. With the small amounts of water need by a family or small group, the most practical way to collect the water is though an infiltration gallery or well. Either method reduces the turbidity of the collected water making it easy for later treatment. The best way to identify their presence is by a lab test of the water or by speaking with your county health department. Unless you are down stream of mining trailings or a factory, the problem will probably affect the whole county or region.
Heavy metals are unlikely to be present in sufficient levels to cause problems with short term use.
Turbidity Turbidity refers to suspended solids, i.e. muddy water is very turbid. Organic compounds Water can be contaminated by a number or organic compound such as chloroform, gasoline, pesticides, and herbicides. These contaminants must be identified in a lab test. It is unlikely ground water will suddenly become contaminated unless a quantity of chemicals is allowed to enter a well. In order to insure cyst filtration, filters with an absolute pore size of 1 um or less should be used.