U.S. Environmental Protection Agency
Secondary Drinking Water Regulations:
Guidance for Nuisance Chemicals
What are Secondary Standards?
What are Secondary Standards?
The U.S. Environmental Protection Agency (EPA) has established National Primary Drinking Water Regulations that set mandatory water quality standards for drinking water contaminants. These are enforceable standards called "maximum contaminant levels" or "MCLs", which are established to protect the public against consumption of drinking water contaminants that present a risk to human health. An MCL is the maximum allowable amount of a contaminant in drinking water which is delivered to the consumer .
In addition, EPA has established National Secondary Drinking Water Regulations that set non-mandatory water quality standards for 15 contaminants. EPA does not enforce these "secondary maximum contaminant levels" or "SMCLs." They are established only as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color and odor. These contaminants are not considered to present a risk to human health at the SMCL.
Why Set Secondary Standards?
Since these contaminants are not health threatening at the SMCL, and public water systems only need test for them on a voluntary basis, then why it is necessary to set secondary standards?
EPA believes that if these contaminants are present in your water at levels above these standards, the contaminants may cause the water to appear cloudy or colored, or to taste or smell bad. This may cause a great number of people to stop using water from their public water system even though the water is actually safe to drink.
Secondary standards are set to give public water systems some guidance on removing these chemicals to levels that are below what most people will find to be noticeable.
What problems are caused by THESE contaminants?
There are a wide variety of problems related to secondary contaminants. These problems can be grouped into three categories: Aesthetic effects
Odor and Taste are useful indicators of water quality even though odor-free water is not necessarily safe to drink. Odor is also an indicator of the effectiveness of different kinds of treatment. However, present methods of measuring taste and odor are still fairly subjective and the task of identifying an unacceptable level for each chemical in different waters requires more study. Also, some contaminant odors are noticeable even when present in extremely small amounts. It is usually very expensive and often impossible to identify, much less remove, the odor-producing substance.
* Standards related to odor and taste: Chloride, Copper, Foaming Agents, Iron, Manganese pH, Sulfate, Threshold Odor Number (TON), Total Dissolved Solids, Zinc.
Color may be indicative of dissolved organic material, inadequate treatment, high disinfectant demand and the potential for the production of excess amounts of disinfectant by-products. Inorganic contaminants such as metals are also common causes of color. In general, the point of consumer complaint is variable over a range from 5 to 30 color units, though most people find color objectionable over 15 color units. Rapid changes in color levels may provoke more citizen complaints than a relatively high, constant color level.
* Standards related to color: Aluminum, Color, Copper, Foaming Agents, Iron, Manganese, Total Dissolved Solids.
Foaming is usually caused by detergents and similar substances when water has been agitated or aerated as in many faucets. An off-taste described as oily, fishy, or perfume-like is commonly associated with foaming. However, these tastes and odors may be due to the breakdown of waste products rather than the detergents themselves.
* Standards related to foaming: Foaming Agents.
Skin discoloration is a cosmetic effect related to silver ingestion. This effect, called argyria, does not impair body function, and has never been found to be caused by drinking water in the United States. A standard has been set, however, because silver is used as an antibacterial agent in many home water treatment devices, and so presents a potential problem which deserves attention.
* Standard related to this effect: Silver.
Tooth discoloration and/or pitting is caused by excess fluoride exposures during the formative period prior to eruption of the teeth in children. The secondary standard of 2.0 mg/L is intended as a guideline for an upper boundary level in areas which have high levels of naturally occurring fluoride. It is not intended as a substitute for the lower concentrations (0.7 to 1.2 mg/L) which have been recommended for systems which add fluoride to their water. The level of the SMCL was set based upon a balancing of the beneficial effects of protection from tooth decay and the undesirable effects of excessive exposures leading to discoloration.
* Standard related to this effect: Fluoride.
Corrosivity, and staining related to corrosion, not only affect the aesthetic quality of water, but may also have significant economic implications. Other effects of corrosive water, such as the corrosion of iron and copper, may stain household fixtures, and impart objectionable metallic taste and red or blue-green color to the water supply as well. Corrosion of distribution system pipes can reduce water flow.
* Standards related to corrosion and staining: Chloride, Copper, Corrosivity, Iron, Manganese, pH, Total Dissolved Solids, Zinc.
Scaling and sedimentation are other processes which have economic impacts. Scale is a mineral deposit which builds up on the insides of hot water pipes, boilers, and heat exchangers, restricting or even blocking water flow. Sediments are loose deposits in the distribution system or home plumbing.
* Standards related to scale and sediments: Iron, pH, Total Dissolved Solids, Aluminum.
Table I. Secondary Maximum Contaminant Levels
Contaminant Secondary MCL Noticeable Effects above the Secondary MCL
Aluminum 0.05 to 0.2 mg/L* colored water
Chloride 250 mg/L salty taste
Color 15 color units visible tint
Copper 1.0 mg/L metallic taste; blue-green staining
Corrosivity Non-corrosive metallic taste; corroded pipes/ fixtures staining
Fluoride 2.0 mg/L tooth discoloration
Foaming agents 0.5 mg/L frothy, cloudy; bitter taste; odor
Iron 0.3 mg/L rusty color; sediment; metallic taste; reddish
or orange staining
Manganese 0.05 mg/L black to brown color; black staining; bitter
Odor 3 TON (threshold "rotten-egg", musty or chemical smell
pH 6.5 - 8.5 low pH: bitter metallic taste; corrosion
high pH: slippery feel; soda taste; deposits
Silver 0.1 mg/L skin discoloration; graying of the white part
of the eye
Sulfate 250 mg/L salty taste
Total Dissolved 500 mg/L hardness; deposits; colored water;
Solids (TDS) staining; salty taste
Zinc 5 mg/L metallic taste
- mg/L is milligrams of substance per liter of water
How can these Problems be Corrected?
Although state health agencies and public water systems often decide to monitor and treat their supplies for secondary contaminants, federal regulations do not require them to do this. Where secondary contaminants are a problem, the types of removal technologies discussed below are corrective actions which the water supplier can take. They are usually effective depending upon the overall nature of the water supply.
Corrosion control is perhaps the single most cost-effective method a system can use to treat for iron, copper and zinc due to the significant benefits in (1) reduction of contaminants at the consumer's tap, (2) cost savings due to extending the useful life of water mains and service lines, (3) energy savings from transporting water more easily through smoother, uncorroded pipes, and (4) reduced water losses through leaking or broken mains or other plumbing. This treatment is used to control the acidity, alkalinity or other water qualities which affect pipes and equipment used to transport water. By controlling these factors, the public water system can reduce the leaching of metals such as copper, iron, and zinc from pipes or fixtures, as well as the color and taste associated with these contaminants. It should be noted that corrosion control is not used to remove metals from contaminated source waters.
Conventional treatments will remove a variety of secondary contaminants. Coagulation/ flocculation and filtration removes metals like iron, manganese and zinc. Aeration removes odors, iron and manganese. Granular activated carbon will remove most of the contaminants which cause odors, color, and foaming.
Non-conventional treatments like distillation, reverse osmosis and electrodialysis are effective for removal of chloride, nitrates, total dissolved solids and other inorganic substances. However, these are fairly expensive technologies and may be impractical for smaller systems.
Non-treatment options include blending water from the principal source with uncontaminated water from an alternative source.
What Can You Do?
If you are concerned about the presence of secondary contaminants in your drinking water supply, here are a few suggestions:
* FIRST, identify your local public water system. If you pay a water bill, the name, address, and telephone number of your supplier should be on the bill. If you do not pay a water bill, then contact your landlord, building manager, or the local health department — they should know.
* SECOND, contact your local public water system. Inquire about your supplier's monitoring for secondary contaminants. Ask for the list of secondary contaminants which are being monitored in your water supply. Does the water being delivered to the public meet these SMCLs? If you have not yet received notice from your supplier, ask how you can get a copy of the monitoring results.
* THIRD, if you receive a public notice from your local public water system regarding other drinking water standards
* FOURTH, contact your state drinking water program if your water supplier is unable to provide the information you need. Ask if your water supplier is consistently in compliance with both primary and secondary drinking water regulations. Request a copy of monitoring results that were submitted to the State by your supplier. Your state drinking water program is usually located in the state capital (or another major city), and is often part of the department of health or environmental regulation. Consult the blue "government pages" of your local phone book for the proper address and phone number, or call the Safe Drinking Water Hotline.
* FIFTH, support rate increases for your local water supplier, where necessary, to upgrade your supplier's treatment facilities to meet drinking water standards.
* FINALLY, if you have a private well and you think that the well may be near a source of contamination or may have been contaminated — HAVE YOUR WATER TESTED by a certified laboratory. A list of certified labs is available from your state's laboratory certification officer. A list of the certification officers can be obtained from the Safe Drinking Water Hotline.
For More Information
For more information on secondary contaminants, write or call the EPA. Ask for a list of the primary and secondary contaminants, about monitoring requirements for these, and for a list of the health advisories available for these contaminants.
or call the Safe Drinking Water Hotline
Update September 12, 2008
Report: Drugs in drinking water of more Americans
Testing prompted by an Associated Press story that revealed trace amounts of pharmaceuticals in drinking water supplies has shown that more Americans are affected by the problem than previously thought — at least 46 million.
That's up from 41 million people reported by the AP in March as part of an investigation into the presence of pharmaceuticals in the nation's waterways.
HEALTH BLOG: Do you drink bottled or tap?
The AP stories prompted federal and local legislative hearings, brought about calls for mandatory testing and disclosure, and led officials in at least 27 additional metropolitan areas to analyze their drinking water. Positive tests were reported in 17 cases, including Reno, Savannah, Ga., Colorado Springs, and Huntsville, Ala. Results are pending in three others.
The test results, added to data from communities and water utilities that bowed to pressure to disclose earlier test results, produce the new total of Americans known to be exposed to drug-contaminated drinking water supplies.
FIND MORE STORIES IN: Boston | Alabama | Georgia | New York City | Phoenix | Colorado Springs | Reno | Savannah | Huntsville | Department of Environmental Protection | Steve Berry | Andy Ryan | Seattle Public Utilities
The overwhelming majority of U.S. cities have not tested drinking water while eight cities — including Boston, Phoenix and Seattle — were relieved that tests showed no detections.
"We didn't think we'd find anything because our water comes from a pristine source, but after the AP stories we wanted to make sure and reassure our customers," said Andy Ryan, spokesman for Seattle Public Utilities.
The substances detected in the latest tests mirrored those cited in the earlier AP report.
Chicago, for example, found a cholesterol medication and a nicotine derivative. Many cities found the anti-convulsant carbamazepine. Officials in one of those communities, Colorado Springs, say they detected five pharmaceuticals in all, including a tranquilizer and a hormone.
"This is obviously an emerging issue and after the AP stories came out we felt it was the responsible thing for us to do, as a utility, to find out where we stand. We believe that at these levels, based on current science, that the water is completely safe for our customers," said Colorado Springs spokesman Steve Berry. "We don't want to create unnecessary alarm, but at the same time we have a responsibility as a municipal utility to communicate with our customers and let them know."
Fargo's water director, Bruce Grubb, said the concentrations of three drugs detected there were so incredibly minute — parts per trillion — that he sent them to the local health officer to figure out how to interpret the information for the community.
"We plan to put this into some kind of context other than just scientific nomenclature, so folks can get some level of understanding about what it means," said Grubb.
The drug residues detected in water supplies are generally flushed into sewers and waterways through human excretion. Many of the pharmaceuticals are known to slip through sewage and drinking water treatment plants.
While the comprehensive risks are still unclear, researchers are finding evidence that even extremely diluted concentrations of pharmaceutical residues harm fish, frogs and other aquatic species in the wild and impair the workings of human cells in the laboratory.
And while the new survey expands the known extent of the problem, the overwhelming majority of U.S. communities have yet to test, including the single largest water provider in the country, New York City's Department of Environmental Protection, which delivers water to 9 million people.
In April, New York City council members insisted during an emergency hearing that their drinking water be tested. But DEP officials subsequently declared that "the testing of finished tap water is not warranted at this time."
Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
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