Drinking Water Facts…..
Drinking Water
Treatment Systems
By: Barbara Daniels and Nancy Mesner
Revised December 2010
If your home water comes from a public water supply, it has been tested and meets EPA standards for
drinking water. If you use a private well, however, you are responsible for assuring that the water is
safe to drink. This means that you should periodically have your water tested, make sure your well is
in proper condition without faulty well caps or seals, and identify and remove potential sources of contamination to your well such as leaking septic systems or surface contamination.
With a private well, you are also responsible for any treatment your water may need if it contains harmful pollutants or contaminants that affect the taste, odor, corrosiveness or hardness of the water. This
fact sheet discusses different types of water treatment systems available to homeowners. Addressing
the source of the problem is often less costly in the long run than installing and maintaining a water
system. For more information on identifying pollutant sources, problems with your well, or help in
testing your well water, see the references at the end of this fact sheet.
There are many types of water treatment systems available. No one type of treatment can address every
water quality problem, so make sure you purchase the type of equipment that can effectively treat your
particular water quality issue. The table below can help direct you to the right solution for your problem.
Drinking Water Facts…..
What type of water treatment is needed?
The table below lists common water contamination problems.
Contaminant or Problem
Possible Cause of Problem
Solutions
The following pollutants are health hazards and must be treated for the safety of your family. If you
cannot successfully remove these pollutants, you should find an alternative source of water.
Arsenic
Naturally occurring in water in some
areas
Reverse osmosis; ion exchange
Bacteria
Well not sealed; sewage, manure or
surface runoff
Remove source of bacteria; chlorination; ozonation; UV disinfection
Lead
Corrosive water, lead pipes or lead
solder
Replace plumbing; reverse osmosis;
distillation
Nitrate
Well not sealed; faulty septic system;
animal waste; fertilizers
Pesticides & Organic chemicals
Use of pesticides, chemicals near water
source
Remove source of nitrate; distillation;
reverse osmosis; anion exchange
(water softener)
Activated carbon filter; reverse osmosis; distillation
The contaminants below are not health hazards, but you may choose to treat because of aesthetic reasons.
Bad odor, color, taste
Variety of sources
Ion exchange; activated carbon filter;
chlorination
Cloudy or dirty water
Fine sand, clay, or other particles
Mechanical filter
Hardness
Naturally occurring minerals in water
Ion exchange (water softener)
Rotten egg odor
Hydrogen sulfide gas
Chlorination and activated carbon filter
Staining of sink and/or laundry, from
iron or manganese
Naturally occurring in water, especially deep wells
Ion exchange or green sand filter (0-10
ppm); chlorination and filtration (if
over 10 ppm)
Drinking Water Facts…..
Ion exchange (water softener)
•
Treats hard water (calcium and magnesium);
•
Removes barium, radium, dissolved iron, manganese;
•
Removes some bad odors, colors and tastes;
•
Anion exchange unit can remove nitrate and fluoride;
•
System cost: $400 - $1000 (plus installation).
An ion exchange column is one of the most common water treatment systems found in the home. Also
known as a water softener, a cation exchange system will remove calcium and magnesium compounds,
barium, radium, and low concentrations of dissolved iron and manganese. An anion exchange unit can also
be installed which will remove nitrate and fluoride.
Ion exchange works by passing water through resin beads. In cation exchange units, the beads are coated
with positively charged sodium ions. These sodium ions exchange places with calcium, magnesium and
other “hard” ions in the water. In anion exchange columns, the resin beads are coated with negatively
charged chloride or hydroxide ions, which exchange with nitrate or fluoride in your water.
Ion exchange systems need to be periodically charged so that coating ions are available. Many water softener systems automatically recharge from a sodium storage tank. People with hypertension or high blood
pressure should be aware that water treated with a water softener contains an elevated level of sodium.
www.systemsaver.com
Drinking Water Facts…..
Distillation
•
Removes lead, nitrate, sodium chloride, pesticides, organic compounds;
•
System cost: $300 (counter-top) - $1700(automatic), plus electricity to run.
A distillation unit works by evaporating water and collecting the steam that is produced. Impurities in
the water are left behind. Distillation can remove lead, nitrate, sodium chloride, and many pesticides
and organic compounds. Distilled water often has a flat or bland taste,
due to the removal of minerals.
The distillation process is slow and requires a lot of water – a typical
distiller produces two to five gallons a day, and requires five gallons
of water for every gallon of distilled water produced. A distiller must
be cleaned frequently and consumes significant electricity to heat the
water.
Envplan240.pbwiki.com
Reverse Osmosis
•
Removes radium, sulfate, calcium, magnesium, potassium, nitrate, fluoride, phosphorous;
•
Removes some pesticides and organic compounds;
•
System cost: $100 (under sink) - $400 (whole house) (plus installation).
In the reverse osmosis process, water passes through a semi-permeable membrane which removes inorganic minerals like radium, sulfate, calcium, magnesium, potassium, sodium, nitrate, fluoride, and
phosphorous. It also helps to remove some organic compounds including some pesticides. Often, reverse osmosis units are used in combination with a mechanical filter and an activated carbon filter. The
water passes through the mechanical filter first, where sand and large particles are removed, then
through the reverse osmosis unit, and lastly through the activated carbon filter which removes organic
compounds.
Reverse osmosis units are relatively expensive to install, and use large amounts of water. Anywhere
from four to nine gallons of water are required for every gallon of treated water produced. Water
should be tested periodically to make sure the membrane is intact and properly functioning.
http://thetashmans.files.wordpress.com/2010/09/reverse_osmosis.jpg
http://www.pure-pro.com/reverse_osmosis_q.htm
Drinking Water Facts…..
Disinfection Methods
Chlorination
•
Kills bacteria and some viruses (Note—does not kill Cryptosporidium, Giardia, and some
other microscopic organisms);
•
Removes some bad odors, tastes and colors;
•
System cost (continuous chlorinator): $500 - $1300.
Chlorine added to water kills most bacteria and some viruses. Water can be chlorinated in two ways: a
“shock” chlorination in which a strong chlorine solution is pumped through a well or plumbing system
to kill bacteria on a one-time basis; or chlorine is added continuously through a chemical feed pump to
constantly kill bacteria. Shock chlorination is usually used when a pump or well has just been installed
to kill bacteria that may have been on the pipes or installation equipment, or if a well has become contaminated by a faulty cap or seal. Continuous chlorination is used when the source of the bacteria in the
water cannot be eliminated.
Chlorination has a residual effect in water – it continues to disinfect for some time after treatment. If
followed by mechanical or activated carbon filtration, chlorination can also remove hydrogen sulfide,
and dissolved iron and manganese.
Chlorine can impart a disagreeable taste and smell to the treated water. Also, if the water being treated
contains organic molecules, the formation of hazardous chlorinated organic compounds
(trihalomethanes) is possible.
UV Radiation
•
Kills bacteria, some viruses;
•
System cost: $250 (under sink) - $1000+ (whole house).
This type of water treatment uses a mercury arc lamp to kill pathogens in the water. UV radiation kills
most bacteria and some viruses, but is ineffective against cysts (such as Giardia) and worms. Cloudy or
turbid water can reduce the effectiveness of UV radiation. UV lamps should be replaced annually or as
suggested by the
manufacturer, as they become less effective with time.
Ozonation
•
Kills bacteria, some viruses;
•
Removes some pesticides, can remove iron, sulfur, manganese;
•
System cost: $250 (portable) - $2000 (whole house).
Ozone occurs naturally in our atmosphere; in fact the ozone layer in our atmosphere protects us from
ultraviolet radiation coming from the sun. In ozonation of water, electrically generated ozone kills bacteria and some other pathogens, and removes some pesticides. In combination with an activated carbon
or mechanical filter, ozonation oxidizes and precipitates out iron, sulfur, and manganese. Ozone does
not produce any taste or odor in the water.
Ozone generators are relatively expensive to install. Ozonation does not have any residual effect in the
water, unlike chlorination.
Drinking Water Facts…..
Filtration Methods
Activated Carbon
•
Removes organic compounds, pesticides, radon gas;
•
Removes hydrogen sulfide, mercury, chlorine, some cysts;
•
System cost: $30 (faucet mount) - $450 (whole house);
•
Solid Block Activated Carbon filters can remove Cryptosporidium and Giardia cysts.
Activated carbon filters absorb organic compounds and remove them from the water. These filters can
remove volatile organic compounds, some pesticides, radon gas, hydrogen sulfide, mercury, and residual chlorine. Activated carbon filters are often used in combination with other water treatments such as
reverse osmosis, chlorination, and ozonation.
There are different types of activated carbon filters. Granular activated carbon (GAC), composed of
loose granules of carbon, have some problems associated with their use. GAC filters accumulate the
organic impurities they remove from the water, but these impurities can then become food for bacteria.
Also, the filter can become saturated with organics, which are then released back into the water. Finally, channels can form between the granules in the filter, which reduces contact time between the water and carbon, resulting in less effective filtration.
Solid block activated carbon filters (SBAC) are a solid compressed block of activated carbon. In addition to removal of chemicals mentioned above, the carbon is so tightly compressed that it can filter out
some cysts such as Giardia and Cryptosporidium. Because SBAC filters are so fine, they easily become plugged with particulate matter, and frequently need to be replaced. They are also more expensive than granular activated carbon filters.
Inadequately maintained carbon filters can become breeding grounds for bacteria, so the filters need to
be kept clean and replaced as recommended by the manufacturer. If a carbon filter is unused for several
days, run water through it for at least 30 seconds to flush any bacteria.
Mechanical
•
Removes sand, silt, clay, organic matter;
•
System cost: $35 (single faucet) - $550+ (whole house).
Mechanical water filters remove suspended material from water, including sand, silt, clay and organic
matter. This filtration system does not remove dissolved or very fine particles and is often used in combination with other water treatment equipment. Mechanical filters commonly consist of fabric, fiber,
ceramic or other screening material. Mechanical water filtration system can be cartridge units, mounted
in a single waterline or on a tap, or tank units, which treat an entire household water supply. The filters
must be serviced periodically.
Drinking Water Facts…..
Filtration Methods — continued
Green Sand
•
Removes iron and manganese up to 10 ppm, prevents rotten egg smell (hydrogen sulfide);
•
System cost: $600 - $1200 (whole house).
Manganese green sand filters remove iron, manganese and hydrogen sulfide (rotten egg odor). As water is passed through the filter, soluble iron and manganese are pulled from solution and later react to
form insoluble iron and manganese. Insoluble iron and manganese build up in the green sand filter and
must be removed by backwashing. Backwashing should be done regularly twice a week or as recommended by the manufacturer.
Periodically, the green sand must also be regenerated by washing with a permanganate solution. Regeneration will leave the green sand grains coated once again with a manganese material that adsorbs
soluble iron and manganese. Follow the manufacturer’s recommendations for frequency of regeneration.
References
Bach, Annette, and Darnell Lundstrom. 1988. Household Water Treatment. HE-430, North Dakota
State University Extension Service, Fargo, North Dakota.
Pfeil, Adel. 2001. Buying Home Water Treatment Equipment. WQ-6, Purdue University Cooperative
Extension Service, West Lafayette, Indiana.
Mesner, Nancy. 2010. How to Protect Your Well Water. WQFA 1. Fact Sheet 1, Utah State University Water Quality Extension, Utah State University.
Seelig, Bruce, Russell Derickson, and Fred Bergsrud. 1992. Treatment Systems for Household Water
Supplies: Iron and Manganese Removal. AE-1030, North Dakota State University Extension Service.
University of Illinois Extension. 1995. Selective Effective Water-treatment Methods. In 57 Ways To
Protect Your Home Environment. College of Agricultural, Consumer and Environmental Sciences,
University of Illinois.
Utah State University. Water Quality Extension. www.extension.usu.edu/waterquality.
Wagenet, Linda, and Ann Lemley. 1988. Questions to Ask When Purchasing Water Treatment Equipment. Water Treatment Notes Fact sheet 1, Cornell Cooperative Extension, New York State College
of Human Ecology.
Drinking Water Facts…..
Before You Purchase Water Treatment Equipment...
The National Sanitary Foundation (NSF) is an excellent resource for anyone who is considering a purchase of a water treatment system. It is an independent, non-profit group of scientists, engineers, technicians, educators and analysts who test and certify drinking water treatment (and other) equipment. At
their Web site, www.nsf.org, you can find out if a particular product is certified to perform as advertised. When purchasing equipment, check to see if it has the NSF mark or listing on it.
Questions to ask a water treatment professional
If you have determined there is a water quality problem that needs treatment, here are some questions
to ask a manufacturer or distributor of water treatment equipment.
1. What exactly does the water analysis show? Do more tests need to be done? Many water treatment
companies will offer free water testing. Make sure you understand the results. In-home quick tests
of hardness, pH, iron and sulfur are possible; tests for organic chemicals require laboratory analysis. Be wary if the quick testing results claim the presence of organics.
2. Are the products and manufacturer rated by the NSF (see above)?
3. Is there a list of referrals you can contact? How long has the company been in business?
4. Does the water quality problem require whole-house treatment, or will single-tap treatment be sufficient?
5. Is the water treating capacity of the system adequate? Will it produce enough treated water for daily
needs?
6. Are there parts to be cleaned or filters to be replaced? Is there an indicator light on the unit in case
of a malfunction? Make sure you understand the maintenance required, as many systems will not
operate effectively without proper maintenance.
7. What is the total purchase price, including installation? What are the expected maintenance costs
(filter replacement, cleaning, etc)? Will the system use significant amounts of electricity? What is
the expected lifetime of the system?
For more information, contact USU Water Quality Extension at 435-797-2580 or visit our website at
http://extension.usu.edu/waterquality
Utah State University is committed to providing an environment free from harassment and other forms of illegal discrimination based on race, color, religion, sex,
national origin, age (40 and older), disability, and veteran’s status. USU’s policy also prohibits discrimination on the basis of sexual orientation in employment and
academic related practices and decisions. Utah State University employees and students cannot, because of race, color, religion, sex, national origin, age, disability, or
veteran’s status, refuse to hire; discharge; promote; demote; terminate; discriminate in compensation; or discriminate regarding terms, privileges, or conditions of
employment, against any person otherwise qualified. Employees and students also cannot discriminate in the classroom, residence halls, or in on/off campus, USUsponsored events and activities. This publication is issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the
U.S. Department of Agriculture, Noelle E. Cockett, Vice President for Extension and Agriculture, Utah State University. . NR/WQ/2005-24
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