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Water Quality

Home Based Water Treatment

Water Chemistry In most US households drinking water is safe, however home based water treatment may improve the taste. In addition treatment may help those that may be vulnerable to some diseases. There are two approaches for home water treatment systems. Point-of-use (POU) systems treat water at a single tap. Point-of-entry (POE) systems treat water used throughout the house. Both approaches utilize contaminant removal technologies such as filtration, ion exchange, reverse osmosis, and distillation. A summary of these water treatments may be found below.

Water Treatment Methods
What It Does to Water
Treatment Limitations
Activated Carbon Filter (includes mixed media that remove heavy metals)
Adsorbs organic contaminants that cause taste and odor problems. Is efficient in removing metals such as lead and copper.
Some designs remove chlorination byproducts. Does not remove nitrate, bacteria or dissolved minerals.
Some types remove cleaning solvents and pestisides.  

Ion Exchange Unit

(with activated alumina)

Removes minerals, particularly calcium and magnesium that make water "hard." If water has oxidized iron or iron bacteria, the ion-exchange resin will become coated or clogged and lose its softening ability.
Some designs remove radium and barium.  
Removes fluoride.  
Reverse Osmosis Unit (with carbon)
Removes nitrates, sodium, other dissolved inorganics and organic compounds.  
Removes foul tastes, smells or colors.  
May also reduce the level of some pesticides, dioxins and chloroform and petrochemicals.  
Distillation Unit
Removes nitrates, bacteria, sodium, hardness, dissolved solids, most organic compounds, heavy metals, and radionucleides. Does not remove some volatile organic contaminants, certain pesticides and volatile solvents.
Kills bacteria. Bacteria may recolonize on the cooling coils during inactive periods.

Online Water related Courses

Of course a more low tech and cost effective approach to improving home water especially in emergencies is to:
  • Boil the water.
  • Purify the water with clorine.
  • Disinfect the water with strong sunlight for 6 hours.
  • Use flocculation-disinfection sachets to clean and disinfect the water.

The Procter & Gamble Company (P&G) developed PUR Purifier of Water™ in conjunction with the Centers for Disease Control and Prevention. The PUR product is a small sachet containing powdered ferric sulfate (a flocculant) and calcium hypochlorite (a disinfectant).

Benefits, Drawbacks, and Appropriateness for
Home Based Water Treatment*

The benefits for Home Based Water Treatment are:
• Proven reduction of bacteria, viruses, and protozoa in water;
• Removal of heavy metals and pesticides;
• Residual protection against contamination;
• Proven health impact;
• Acceptable to users because of visual improvement in the water;
• Sachets are easily transported due to their small size, long shelf life, and classification as non-hazardous material for air shipment.
The drawbacks of flocculant/disinfectant powders are:
• Multiple steps are necessary to use the product, which requires a demonstration to teach new users;
• The need for users to have, employ, and maintain two buckets, a cloth, and a stirring device;
• The higher relative cost per liter of water treated compared to other household water treatment options.

 *Environmental Health at USAID

PUR is most appropriate in areas with a consistent supply chain for sachet resupply, and in urban, rural, and emergency situations where educational messages can reach users to encourage correct and consistent Home Based Water Treatment.