It is not possible to tell whether water is safe to drink just by looking at it. Simple procedures such as boiling or the use of a household charcoal filter are not sufficient for treating water from an unknown source. Even natural spring water, considered safe for all practical purposes in the 1800s, must now be tested before determining what kind of treatment is needed. Laboratory analysis, while expensive, is the only way to identify the contaminants in water.

One of the most thorough systems for household use is reverse osmosis, which uses mechanical pressure to force water through a semi-permeable membrane that allows pure water to pass through a membrane, leaving behind everything else.

Such systems typically include four or five stages:

  • a sediment filter to trap particles including rust and calcium carbonate
  • optionally a second sediment filter with smaller pores
  • an activated carbon filter to trap organic chemicals, including chlorine which will attack and degrade reverse osmosis membranes
  • a reverse osmosis (RO) filter which is a thin film composite membrane
  • optionally a second carbon filter to capture those chemicals not removed by the RO membrane
  • optionally an ultra-violet lamp is used for disinfection of any microbes that may escape filtering by the reverse osmosis membrane

Contaminants that may be in untreated water include microorganisms such as viruses and bacteria; inorganic contaminants such as salts and metals; pesticides and herbicides; organic chemical contaminants from industrial processes and petroleum use; and radioactive contaminants. Water quality depends on the local geology and ecosystem, as well as human uses such as sewage dispersion, industrial pollution, use of regional water bodies, and overuse (which may lower the level of the water).

The Environmental Protection Agency prescribes regulations that limit the amount of certain contaminants in the water provided by public water systems for tap water. Food and Drug Administration (FDA) establishes limits for contaminants in bottled water but this is not avidly regulated. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants.

Toxic substances and high populations of certain microorganisms can present a health hazard for non-drinking purposes such as irrigation, recreation and industrial uses. These conditions may also impact wildlife which use the water for drinking or as habitat.

In the home, Natural Cures recommends at least a reverse osmosis system in the kitchen, where food is prepared, and shower filters to keep contaminants from being absorbed by the skin. Even better is a whole house system that filters all the water used in the home. There are high quality reverse osmosis systems available online, but we suggest that you start with your local water store, where the staff is likely to know what local water issues are, and what system would work best with the water source in your home.