Home Water Treatment Devices – Drinking Water and Human Health

The table below outlines information on specific home water treatment approaches. Keep in mind that some water treatment can be for aesthetic as well as health factors. If drinking water poses a health risk, the consumer may also consider the cost of purchasing bottled water or tying into a public water system if available as an alternative to treatment.
If you need to contact a water treatment professional to install or repair a home treatment system or to assess a problem, be prepared to ask questions that may save you time, money, and frustration in the future.

Device	Primary Use	Limitations
Activated Carbon Filter	Removes chlorine, volatile organic compounds (VOCs), radon, some Synthetic Organic Compounds (SOCs), and general taste and odor problems	Does not remove nitrate, bacteria or inorganic compounds. Periodic replacement of activated charcoal required.
Reverse Osmosis	Removes more contaminants than any other treatment system except distillation, some organic chemicals (not volatile or semi volatile), pesticides, bacteria and viruses.	Does not remove all organic chemicals, such as chloroform. Does not remove 100 percent of most chemicals. Uses large amounts of water. Not recommended for bacteria and dissolved gases
Ion Exchange	Cation Exchange Units – Removes positively charged ions, inorganic compounds, such as iron and manganese ions, arsenic, chromium, and hard water minerals – calcium and magnesium. Anion Exchange Units – Removes negatively charged ions such as nitrates, bicarbonate, selenium, and sulfate.	Removal of one type of ion replaced with another, for example iron removed may be replaced with sodium. Periodic backwashing and regeneration required.
Filtration	Removes small particles and suspended solids such as ferric iron, clay, silt and sand, and some pathogens such as bacteria and viruses, and colloids (suspended matter).	Filter replacement based on concentration of contaminant, pressure head loss, and water usage in the home.
Distillation	Removes dissolved minerals, trace amounts of metals, and some toxic organic chemicals.	Might produce bland-tasting water. Small capacity units produce limited quantity for drinking, cooking. Large units require kitchen or adjoining space or small diameter plastic plumbing can be run to the faucet location from a basement unit. Not effective against most volatile and semi-volatile chemicals and some bacteria.
Aeration	Dissolved gases like radon, carbon dioxide, methane, and hydrogen sulfide, as well as volatile organic compounds, like MTBE or industrial solvents. Aeration can be used for the precipitation and removal of dissolved iron and manganese.	If iron and manganese are present in solid form, pre-treatment of the water to remove these particles before entering the aeration treatment and post-treatment may be necessary. Waste air must be vented from house in such a way as to prevent contamination of indoor air quality.
Ultraviolet Radiation	Efficient at inactivating vegetative and sporous forms of bacteria, viruses, and other pathogenic microorganisms.	Not recommended if the untreated water contains high levels of total coliform bacteria, substantial color or turbidity. Does not improve the taste, odor, or clarity of water.
Ozone	Pathogenic (disease-causing) organisms including bacteria and viruses, phenols (aromatic organic compounds), some color, taste, and odor problems, iron and manganese, and turbidity.	Not effective for large cysts and some other large organisms, inorganic chemicals, heavy metals
Activated Alumina	Used primarily for removing fluoride and arsenic	May require a post-treatment system for bacteria removal.
Chlorination	Used to treat viruses and bacteria; dissolved iron, manganese, and hydrogen sulfide; iron, manganese and sulfur bacteria	May require a post-treatment system for taste and odor removal.
Oxidation Potassium Permanganate Oxidizing Filters	Used to treat viruses and bacteria; dissolved iron, manganese, and hydrogen sulfide; iron, manganese and sulfur bacteria.	Requires careful calibration and monitoring. Potassium permanganate is a skin irritant.
pH Adjustment	Neutralizing filters and soda ash/ sodium hydroxide injection raise the pH of drinking water to near neutral 7. Acid injection lowers pH to near neutral 7.	pH adjustment does not treat any type of contaminants in water; it serves to lower or raise pH until a neutral level is reached. Neutralizing filters can cause hardness in treated water. Sodium hydroxide and strong acids such as sulfuric acid and hydrochloric acid can be hazardous to handle and store.
Adapted from Household Water Treatment by Annette Bach and Darnell Lundstrom. 25 HF & E-2. NDSU Extension Service, North Dakota State University, Fargo, ND 58105. June 1988.