What are the health implications of iron in drinking water?

As far as is known, humans suffer no harmful effects from drinking waters containing iron. Such waters, when exposed to the air so that oxygen can enter, become turbid and highly unacceptable from the aesthetic viewpoint, owing to the oxidation of iron to the ferric (Fe III) state which form colloidal precipitates. The rates of oxidation are not rapid, and thus reduced forms can persist for some time in aerated waters.

Why do I need a disinfection residual in my distribution system?

The purpose of a disinfection residual in domestic water treatment is to kill disease-causing organisms that may be introduced into the distribution system.

What should the free chlorine residual (halogen residual) be in the distribution system?

A chlorine residual in the form of free available chlorine has the highest disinfecting ability. This ensures that there is available chlorine in the distribution system to effectively destroy any organisms that may enter the system through line repairs, breaks, or from bacteria growing in the transmission lines. The free chlorine residual should be between 0.2-0.7 ppm at the farthest point in the distribution system.

What are the bacteriological monitoring requirements for drinking water systems in the National Park Service?

Monitoring requirements vary by type of system. Please refer to Table 10 of RM 83A to determine what type of system you have and the bacteriological monitoring requirements.

How often am I required to conduct chemical analyses on my water systems?

Monitoring requirements vary by type of system. Please refer to Table 10 of RM 83A to determine what type of system you have and the chemical monitoring requirements.

What are Trihalomethanes (THM's)?

THM's, which include chloroform, are disinfection by-products formed by the interaction of chlorine and natural organic material in the water. While chloroform is carcinogenic, the concentration in most drinking water supplies is minute and the benefits of disinfection outweigh the potential health risks of THM's.

What is a Consumer Confidence Report (CCR)?

Water suppliers must deliver to their customers annual drinking water quality reports (or consumer confidence reports). These reports will tell consumers what contaminants have been detected in their drinking water, how these detection levels compare to drinking water standards, and where their water comes from. The reports must be provided annually before July 1, and, in most cases, are mailed directly to customers' homes. Contact your water supplier to get a copy of your report, or see if your report is posted on-line.

In-depth information on Consumer Confidence Reports (CCR's) from the U.S. Environmental Protection Agency (USEPA)

What are the Drinking Water Standards?

Under the authority of the Safe Drinking Water Act (SDWA), EPA sets standards for approximately 90 contaminants in drinking water. For each of these contaminants, EPA sets a legal limit, called a maximum contaminant level, or requires a certain treatment. Water suppliers may not provide water that doesn't meet these standards. Water that meets these standards is safe to drink, although people with severely compromised immune systems and children may have special needs. For a more detailed description, read about how standards are set or about EPA's Office of Ground Water and Drinking Water.

My water has a funny taste/smell/appearance. What could cause these problems?

Even when water meets EPA's standards, you may still object to its taste, smell, or appearance. EPA sets secondary standards based on these aesthetic characteristics (not health effects) which water systems and states can choose to adopt. Common complaints about water aesthetics include temporary cloudiness (typically caused by air bubbles) or chlorine taste (which can be improved by letting the water stand exposed to the air). For advice on other water quality problems you can feel, smell, taste, or see, go to http://www.epa.gov/safewater/faq/signs.html

Is bottled water safer than tap water?

Bottled water is not necessarily safer than your tap water. EPA sets standards for tap water provided by public water systems; the Food and Drug Administration sets bottled water standards based on EPA's tap water standards. Bottled water and tap water are both safe to drink if they meet these standards, although people with severely compromised immune systems and children may have special needs. Some bottled water is treated more than tap water, while some is treated less or not treated at all. Bottled water costs much more than tap water on a per gallon basis. Bottled water is valuable in emergency situations (such as floods and earthquakes), and high quality bottled water may be a desirable option for people with weakened immune systems. Consumers who choose to purchase bottled water should carefully read its label to understand what they are buying, whether it is a better taste, or a certain method of treatment. More information on bottled water is available from the International Bottled Water Association, which represents most US bottlers.

What can I do if my water isn't considered "safe"?

How will I know if my water isn't safe to drink? A: Your water supplier must notify you by newspaper, mail, radio, TV, or hand-delivery if your water doesn't meet EPA or state standards or if there is a waterborne disease emergency. The notice will describe any precautions you need to take, such as boiling your water. Follow the advice of your water supplier if you ever receive such a notice. The most common drinking water emergency is contamination by disease-causing germs. Boiling your water for one minute will kill these germs. You can also use common household bleach or iodine to disinfect your drinking water at home in an emergency, such as a flood (see EPA's emergency disinfection fact sheet for specific directions on how to disinfect your drinking water in an emergency).

What is a violation of a drinking water standard?

Drinking water suppliers are required to monitor and test their water many times, for many things, before sending it to consumers. These tests determine whether and how the water needs to be treated, as well as the effectiveness of the treatment process. If a water system consistently sends to consumers water that contains a contaminant at a level higher than EPA or state health standards or if the system fails to monitor for a contaminant, the system is violating regulations, and is subject to fines and other penalties. When a water system violates a drinking water regulation, it must notify the people who drink its water about the violation, what it means, and how they should respond. In cases where the water presents an immediate health threat, such as when people need to boil water before drinking it, the system must use television, radio, and newspapers to get the word out as quickly as possible. Other notices may be sent by mail, or delivered with the water bill. Each water suppliers' annual water quality report must include a summary of all the violations that occurred during the previous year.

What contaminants may be found in drinking water?

There is no such thing as naturally pure water. In nature, all water contains some impurities. As water flows in streams, sits in lakes, and filters through layers of soil and rock in the ground, it dissolves or absorbs the substances that it touches. Some of these substances are harmless. In fact, some people prefer mineral water precisely because minerals give it an appealing taste. However, at certain levels minerals, just like man-made chemicals, are considered contaminants that can make water unpalatable or even unsafe. Some contaminants come from erosion of natural rock formations. Other contaminants are substances discharged from factories, applied to farmlands, or used by consumers in their homes and yards. Sources of contaminants might be in your neighborhood or might be many miles away. Your local water quality report tells which contaminants are in your drinking water, the levels at which they were found, and the actual or likely source of each contaminant. Some ground water systems have established wellhead protection programs to prevent substances from contaminating their wells. Similarly, some surface water systems protect the watershed around their reservoir to prevent contamination. Right now, states and water suppliers are working systematically to assess every source of drinking water and to identify potential sources of contaminants. This process will help communities to protect their drinking water supplies from contamination, and a summary of the results will be in future water quality reports.

Can bottled water be used as a permanent replacement for tap water systems?

This topic is currently under review.

Where can I find EPA regulations and other documents related to drinking water?

Check for EPA documents.

What is a Consecutive Water System?

A Consecutive Water System exists when one Public Water System (PWS) supplies water to one or more other PWS's This type of water system may be either a CWS, a NTNC or a TNC water system. A common situation involving Consecutive Water Systems is when one system, called a bulk water supplier, supplies water to other PWS's. For consecutive systems, EPA allows States to decide how each system will conduct monitoring. In some cases, monitoring may be done by only one of the systems "to the extent that the interconnection of the systems justifies treating them as a single system for monitoring purposes" (40 CFR 141.29).

In many cases, States may require the bulk supplier to be responsible for monitoring/treating the source water and the system(s) that receives the water to be responsible for monitoring/maintaining the distribution system that carries the water to the customer. However, monitoring requirements for a Consecutive Water System may vary rule-by-rule, if the State so decides. If a State modifies monitoring for these water systems, the State must provide a schedule detailing the modified monitoring requirements, and EPA must concur with the schedule (45 CFR 141.29)

How does drinking water become contaminated?

Surface waters, such as streams, creeks, and lakes, will almost always contain some degree of contamination. This is due to exposure to animals, humans, aquatic life, etc. Raw surface waters should always be treated prior to domestic use, and must include disinfection and filtration to remove turbidity and parasites that are resistant to simple disinfection. Wells and springs can become contaminated by faulty construction, poor protection from surface activity including rain and flooding, a shallow water table, entrance of unfiltered surface water via rock fractures, close proximity to a sewage disposal system or leaky sewer pipe, and/or contamination during repair or reconstruction. A false, positive coliform count can occur by contaminating the water sample (e.g., putting one's finger into the water sample bottle) or by using a non-approved water sample bottle. A well or spring should be super-chlorinated prior to the coliform test, especially if a repair has been made and the system was not chlorinated at the time.

What are some other forms of water contamination?

Water contaminants commonly found in this area include hydrogen sulfide (rotten egg odor); excess iron (reddish brown stains); iron bacteria (foul taste and odor); manganese (blackish stains, metallic taste); hardness (white deposits, increase in soap usage); salinity; corrosiveness (evidenced by the dissolving of copper plumbing leading to blue-green stains and a bitter taste); turbidity (cloudy and/or dirty water); and sediment. These are not considered health hazards but there are water treatment systems available for the removal /reduction of all of the above. Contact a professional water treatment company for more information. Man-made chemicals, such as pesticides, herbicides, solvents, etc., can easily leach into a subsurface water supply through careless handling and dumping.

What are the differences between Free Chlorine, Residual Chlorine and Total Chlorine. And What are their significance?

The definitions for the various "types" of residuals can be very confusing. The following definitions are from the EPA Drinking Water Glossary - A Dictionary of Technical and Legal Terms Related to Drinking Water (http://www.epa.gov/safewater/Pubs/gloss2.html#R)

Residual chlorine - The amount of free and/or available chlorine remaining after a given contact time under specified conditions.

Free available residual chlorine - That portion of the total available residual chlorine composed of dissolved chlorine gas cl2), hypochlorous acid (HOCl), and/or hypochlorite ion (OCl-) remaining in water after chlorination. This does not include chlorine that has combined with ammonia, nitrogen, or other compounds.

Combined available residual chlorine - The concentration of residual chlorine which is combined with ammonia (NH3) and/or organic nitrogen in water as a chloramine (or other chloro derivative) yet is still available to oxidize organic matter and utilize its bactericidal properties.

Total residual chlorine - The amount of available chlorine remaining after a given contact time. The sum of the combined available residual chlorine and the free available residual chlorine. Also see residual chlorine.

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