water purification

The water purification process removes contaminants from water sources. Methods include carbon treatment, ultraviolet light, deionization, filtration, molecular stripping, water softening, ultrafiltration and reverse osmosis. Although used primarily to produce safe and pleasant drinking water other applications include pharmacological, industrial, medical and chemical uses.

There are a wide range of contaminants that can be removed by a water purification system. These include:

  ~ toxic metals such as lead, copper and chromium
  ~ particulate sand
  ~ minerals such as calcium, silica and magnesium
  ~ suspended particles of organic material
  ~ parasites
  ~ bacteria
  ~ Giardia
  ~ algae
  ~ fungi
  ~ virus

Some substances that are filtered out, particularly in home water purification, are primarily cosmetic. That is, their removal improves the smell, taste and appearance of the water rather than removing dangerous toxins.

Two Common Water Purification Systems

1. Carbon filtering

Charcoal, which is a form of carbon with a high surface area is used to absorb contaminants such as mercury, particulates, large parasites, solvents and pesticides. Passing water through activated charcoal is common in household water filters and fish tanks. Granulated filters are the type most often found in portable pitchers and improve taste and odor. Carbon block filters are generally plumbed into home water purification systems, usually 
through a single faucet in the kitchen, as are Ceramic carbon water filters. The latter have an additional ceramic filter, remove more contaminants and tend to last longer.


2. Reverse Osmosis Water Filtering

When applied to the water purification process, reverse osmosis (hyper-filtration) is the system of filtering water under pressure through a semi-permeable membrane. It is generally considered to be the most effect method of water filtration available. It works by allowing water to pass through a semi-permeable membrane and removing contaminants such as salts, toxins and bacteria.

Reverse osmosis systems are significantly more expensive than other types of filter which are often incorporated into their design. The running costs, however, are very similar to those of solid carbon and ceramic filter systems. And, similarly, reverse osmosis filtering systems are available either fitted to a single faucet or plumbed into the main water supply of the house.

Other water purification methods include:

~ boiling
~ distillation including direct contact membrane distillation (DCMD)
~ ion exchange
~ sand filters
~ electrodeionization
~ portable methods such as water purification tablets
~ ultraviolet water filters