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The Contaminant Removal Table itself begins just below
the Key: type of contaminant; biological, inorganic, or organic. ![]() ![]() about the removal effectiveness of the treatment method on the contaminant. ![]() linked to notes following the chart. ![]() additional information. ![]() taste, acidity & alkalinity, and radon & radium) are discussed after the main table. ![]() thousands. I have included the more important and/or common contaminants in this list. ![]() introduced accidentally) before investing in a treatment method. If you are on municipal water, obtain and read your annual water quality report. If you have a well or use surface water, try to determine which contaminants are most liable to be present (try the local EPA office, local health department, neighbors, local water companies, etc.) and have it tested periodically. |
Key to the Contaminant Removal Table |
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Contaminant type |
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H | Health Hazard |
N | Nuisance contaminant, may cause problems with the plumbing, odors, |
B | Beneficial (in the case of chlorine, the benefit is not because it is an essential mineral, like calcium or copper, rather chlorination has played a critical role in protecting the world's drinking water supply from waterborne infectious diseases for nearly 100 years) |
BH | Contaminant is beneficial at low doses but can cause health problems at higher levels. Fluoride is a classic example. It provides protection from cavities at levels of about 1 part per million (ppm). At 1.5-2 ppm it can cause staining of the teeth, and at 4 ppm or above it may cause bone problems. |
Removal effectiveness of the treatment method on a contaminant |
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D | Disinfection - Effectiveness depends on the proper dose and contact time of the disinfection agent. |
R | Mostly Removed - If the device is working properly |
S | Some Removal - may depend on what chemical form the contaminant is in at the time of treatment, iron and arsenic are examples. |
M | Depends on the manufacturer, particularly for activated carbon filters where special manufacturing processes can increase the level of specific contaminants removed. Ask manufacturer for independent certification of removal (and the percent removal). A claim of "removes or reduces lead" can be true if the unit removes 10% or 99.99%. |
C | Boiling concentrates those contaminants not removed or killed |
add | Some disinfection methods can add contaminants to the drinking water |
Approximate ongoing cost of treatment per gallon 2 (not including the initial cost of the system) | ||||||||||||
Contaminant |
EPA - Basic Information about Regulated Drinking Water Contaminants | |||||||||||
Inorganic Contaminants |
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BN | H | H | BNH | BH | BH | N | H | H | H | depends | ||
Treatment Method | Hard Water, Calcium and Magnesium | Arsenic | Asbestos | Chlorine | Copper | Fluoride |
Iron and/or
Manganese 1 |
Mercury | Lead | Nitrates | Other Inorganics | |
Bottled water | Bottled water is unique among the other treatment methods listed, because the consumer does not have any control over the purification process. All harmful contaminants should be removed by the water bottler. Bottled water, however, does not have to meet any higher levels of purity or safety than tap water. To insure the quality of your bottled water, make certain that you purchase water certified by NSF or that the manufacturer is a member of the International Bottled Water Association (IBWA) | $0.25 to $1.50 or more | ||||||||||
Whole House Treatment: | ||||||||||||
Chlorination A history of: water treatment chlorination |
add | R 1 with filtration |
Less than $0.01 | |||||||||
Water
softener (cation exchange) |
R | S | S 1 | S add 7 |
Less than $0.01 | |||||||
Anion exchange | Cation, anion, or mixed bed ion exchange resins can be used to remove a wide variety of inorganic contaminants. | Depends | ||||||||||
Magnetic conditioning | ? 3 | Less than $0.01 | ||||||||||
Whole house sediment filter | R 1 if precipitated |
Less than $0.01 | ||||||||||
Whole house GAC filter | S 5 best option available |
R 1 if precipitated |
Less than $0.01 | |||||||||
Ozone | R 1 | Less than $0.01 | ||||||||||
Manganese Greensand oxidization filter | S 83% |
R 1 | R some hydrogen sulfide |
Less than $0.01 | ||||||||
Point of Use (POU) Treatment: | ||||||||||||
Hard water, Calcium and Magnesium | Arsenic | Asbestos | Chlorine | Copper | Fluoride |
Iron and/or
Manganese 1 |
Mercury | Lead | Nitrates | Other Inorganics |
Cost |
|
Distillation | R | R | R | R | R | R | R | R | R 99%+ |
R | R | $0.15 to $0.35 |
Reverse Osmosis (RO)
8 membrane filtration |
R | R | R | SM | R | R | R | R | R 85% |
R | R | $0.10 to $0.20 |
"Pitcher" filter - usually uses GAC & perhaps other materials like ion exchange resins 12 | R | M | R 1 if precipitated |
M | M | M | $0.15 to $0.25 | |||||
KDF filter | R | R | R | R | R | S | $0.01 to $0.05 | |||||
Ceramic filter | R | R 1 if precipitated |
Less than $0.01 | |||||||||
Granulated Activated Carbon (GAC) filter 5 | R | R 1 if precipitated |
M | Less than $0.01 to $0.05 | ||||||||
Solid Block Activated Carbon
(SBAC) filter with sub-micron pores My recommendation for a simple, effective solution to many common drinking water problems. 11 |
R | R | R 1 if precipitated |
M | M | $0.05 to $0.10 | ||||||
Activated alumina filtration | R | R | S | add aluminum |
Less than $0.01 | |||||||
Ultraviolet (UV) disinfection 10 | Less than $0.01 | |||||||||||
Boiling (a rolling boil for at least 5 minutes - longer at higher altitudes) | C | C | C | R | C | C | C | C | C | C | C | ? |
Some other drinking water contaminants | Treatment Methods |
Turbidity, suspended fine sand, clay, other small particles | Use sand filtration for large quantities of suspended particulates or use a sediment filter or sedimentation (allowing the particles to settle out of suspension) for smaller quantities of sediment. |
Hydrogen sulfide gas (rotten egg odor) | Remove by using chlorination and a sedimentation filter or an oxidizing (i.e. greensand) filter followed by activated carbon filter. |
Many odor and taste problems other than rotten egg smells | Use an activated carbon filter. |
Sulfate | Remove small amounts for drinking or cooking by RO or distillation. Use ion exchange for whole house treatment. |
Acidity
- pH lower than 7 |
pH correction using either a tank-type neutralizing filter with processed calcium or magnesia in combination with calcium as the media, a chemical feed pump to inject a neutralizing solution (soda ash, potassium or sodium hydroxide) into the water, or a pressure filter tank filled with limestone chips. |
Alkalinity - pH higher than 7 |
pH correction using either a neutralizing filter or chemical-feed pump to lower the pH |
Radon
and Radionucleotides
Click here for more Links |
Aeration is very effective for removing radon from drinking water. Radon can also be removed with an Activated Carbon filter. Radium can be removed with RO, cation exchange, and distillation. |
|
2 - The costs are very approximate because of a wide variety of
factors. Listed costs also do not include the initial expense of the
treatment equipment. |
3 - I am afraid I do not know anything about magnetic or electromagnetic conditioning of water. I do not have a hard water problem and thus have not had a motivation to try the technique. I have also not been able to get any unbiased information on the effectiveness of this treatment. I listed it here because it is a widely advertised alternative to traditional water softening which is not particularly environmental (or health) friendly, and, if it actually works, would be a valuable addition to hard water treatment methods. If anyone has first hand experience with these devices or knows of a link to an independent review article, please let me know, and I will report anything I discover. Back to chart. |
4 - Reverse Osmosis, Ceramic Filters, and
Carbon Block Filters can have pore sizes of 0.5 micron or less (RO membranes are
far smaller) which can remove many harmful bacteria very effectively. It
is best, however, not to depend on these treatments for your primary, ongoing
disinfection method for water that is known (or suspected) to have harmful
bacterial contamination. A damaged filter element could allow enough
bacteria into the "filtered water" stream to cause illness - and there
would be no way to detect the problem without constant testing. They are
definitely reliable enough, however, to be used as a backup system with normally
safe domestic water (in case of accidental contamination) or for water treatment
in case of an emergency where normal water distribution is disrupted and the
available water may be contaminated.. |
5 - Activated carbon, whether as fairly large granules, in granulated
activated carbon (GAC) filters, or compressed into solid carbon blocks filters,
is very effective at removing a wide variety of organic compounds. I
placed a S 5 for whole house and point of use GAC filters
because 1) water moves through a whole house carbon filter (unless it is enormous) too fast for complete removal of anything except particles smaller than the largest pore size (usually 10-20 microns), and 2) GAC filters, because they contain loose carbon particles and are prone to channeling, where the flowing water creates relatively large channels through the filter medium. Water moving through these channels does not have much contact with the activated carbon, and thus, filtration of the channeled water is minimal. |
6 - Iron bacteria are mostly a problem for people using wells water with
high iron or manganese concentrations. The bacteria themselves do not
necessarily clog filters, but the brown slime they produce may. |
8 - A RO systems should come with a pre-filter (a sediment filter and
perhaps a chlorine filter) to remove contaminants that would damage the RO
membranes. A Reverse Osmosis filtration system should also come with a
high quality Activated Carbon filter to remove organic and some inorganic
compounds that are not removed by the RO membranes. Besides RO there
are other types of
membrane filtration (Microfiltration, Ultrafiltration &
Nanofiltration), where water is forced through different size
semi-permeable membranes. |
9 - Water usually contains dissolved gases and may contain other substances, like some of the organic chemicals, that can be volatilized at temperatures below the boiling point. When the boiling point of volatile chemicals is near water, it is difficult to separate these materials from water using distillation. In addition, the separation of steam from the liquid that contains dissolved solids is not absolute. Minute amounts of the dissolved materials will be carried along with the steam. Distillation normally removes over 99.9 percent of many dissolved materials. A gas vent, fractional column, or carbon filter should be included with any distillation system you purchase to remove the volatile contaminants. Back to chart. |
10 - Ultraviolet (UV) light is capable only of
disinfecting water, no other contaminants are removed. Different pathogens
require different doses for treatment (cysts require a higher dose than most
bacteria, for example), so make certain any UV system you consider is capable of
killing the specific microbe(s) you are concerned about. |
11 - Solid Block Activated Carbon Filters are
not usually described separately from loose carbon (GAC) filters.
This article does a good job starting on page 24. The list of
water contaminants and available treatment technologies can be rather
overwhelming. After
all is said and done, though, a high quality, Solid Block Activated Carbon filter
(SBAC) (designed to remove the most common drinking water contaminants) would be my recommendation for
probably 80%+ of people concerned about their drinking water quality -
the other 20%,or so may have more serious contaminant problems, and will need to
explore more complex (and expensive) treatment solutions specific to their
situation. ![]() ![]() ![]() ![]() ![]() ![]() |
Final thoughts and disclaimer:
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Other considerations for purchasing a water treatment system (or bottled
water)
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Copyright © 2005 Randy Johnson. All rights reserved. | Updated November 2011 |