Nutrition Action Healthletter

What’s In Your Tap Water?

The place to start is your local public water utility. If you’re a homeowner, you can find its address and phone number on your bill. If you rent, check the phone book. Many utilities also have Web sites.

   Ask for the latest “Consumer Confidence Report.” That will tell you where your water comes from — whether it’s surface water (from rivers or lakes), ground water (from underground rivers, streams, etc.), or some mix. It will also tell you whether your water exceeds the limits for any of 80 contaminants that are regulated by the Environmental Protection Agency (EPA). You should also ask for a printout of the levels of all 80 contaminants, since the EPA’s limits for arsenic and disinfection byproducts are too high.

   If you get your water from a well, you’ll need to get it tested yourself. Call the EPA Safe Drinking Water Hotline for information on how to obtain a list of certified labs.

Here’s some of what to look for in the information you get about your water:

Total trihalomethanes (TTHMs) below 80 ppb. They’re the most common disinfection byproducts. The EPA’s current limit of 100 ppb (parts per billion) will drop to 80 ppb starting next year.

Turbidity below 0.5 NTU (nephelometric turbidity units). Keep in mind that outbreaks of gastrointestinal illness have occurred at levels as low as 0.2 NTU, which aren’t enough to make the water look cloudy.

Lead below 15 ppb. Since any lead will probably come from the pipes inside your home, a clean bill of health from the water utility doesn’t mean anything. If you want to know how much lead is in your water, you have to test it. Find a certified laboratory through the EPA Safe Drinking Water Hotline. Testing for lead is especially important for apartment dwellers in high-rise buildings, since the water may have to flow through a good deal of pipe before it reaches your faucet.

Arsenic below 10 ppb. Even the EPA admits that its limit (50 ppb) is too high. The World Health Organization’s limit is 10 ppb.

Parasites. Water utilities and labs don’t routinely test for Cryptosporidium, Giardia, or other parasites because the analysis takes days to complete and can’t distinguish live from dead parasites.

^ Top

A Mini-Guide to Water Filters

Filters vary widely in what they can remove, how much they cost, and how expensive they are to maintain. Pitchers or carafes that sit on a countertop or units that are mounted on your faucet can run anywhere from $10 to $75, while most under-the-sink units cost between $100 and $500. Don’t forget to add $25 to $150 a year for replacement filters (not replacing used filter cartridges can make your water more contaminated). Here’s how to choose a filter:

1. Check to see if the filter has been tested and certified by NSF International, a non-profit independent testing organization. A statement on the box or in the product information should list which contaminants the filter is certified to remove under which Standards. If a manufacturer hasn’t paid an independent authority to test its filters, why take a chance on it? The Honeywell faucet-mounted Model NM-5000 box, for example, only says that the filter “has been tested against NSF International protocols....” That’s not as solid a guarantee as a filter that “has been tested and certified by NSF International....”

2. Pick a Standard. NSF’s tests use several “ANSI/NSF Standards” (ANSI stands for the American National Standards Institute). The two most common:

  • Standard 42 covers “aesthetic effects” like removing sulfate, zinc, and other substances that affect “the water’s taste, odor, or color, but that are not considered harmful,” according to NSF.
  • Standard 53 covers “health effects” like reducing Cryptosporidium, lead, turbidity, volatile organic chemicals (which include herbicides, pesticides, and trihalomethanes — the most common disinfection byproduct), and many other contaminants “that may pose a health risk if present in water in concentrations that exceed allowable levels.”
Other protocols cover ultraviolet treatment (Standard 55), reverse osmosis (Standard 58), and distillation (Standard 62).

3. Check the contaminants. A filter is only certified to remove the contaminants that are listed on the box or in the package information. For example, Brita’s Standard Model Water Filtration Pitcher is certified to remove copper, lead, and mercury under Standard 53. Pur’s Model FM-3000/37-500 faucet-mounted filter is certified to remove Cryptosporidium, Giardia, 2,4-D and atrazine (herbicides), lindane (a pesticide), asbestos, lead, mercury, and turbidity under the same Standard (see photo). That may mean that Brita didn’t want to pay to have its filter certified for the other contaminants, or that the filter doesn’t reduce their levels.

click label to view enlarged version

Labels like this one (from a Pur faucet-mounted unit) tell you which contaminants the filter is certified to remove.

4. For more information. For a list of all the units that NSF has tested, and all the contaminants that they remove, send $5 to NSF International for a copy of “Water Wise — The Consumer’s Guide to Safe Drinking Water”. You can also try NSF’s not-too-consumer-friendly Web site ( It’s updated more frequently than the book, but you can only search by company or specific contaminant (start by clicking on “Search for NSF Certified Products,” then “Drinking Water Treatment Units”).

^ Top

A Bottled Water Primer

Is bottled water safer than tap water? There’s no easy answer. It depends on where the bottled or tap water comes from, how (or if) it’s been treated, and who’s drinking it. Even so, the Centers for Disease Control and Prevention (CDC) “hasn’t documented a microbial outbreak of water-borne disease associated with bottled water in the United States,” according to CDC epidemiologist Dennis Juranek. Bottled water comes with many names. Here’s what some of them mean:

Spring water flows naturally to the earth’s surface from underground formations. It makes up about 75 percent of the bottled water sold in the U.S. (the other 25 percent comes from municipal water supplies). Springs are supposed to be protected from pollution, according to industry guidelines and some state regulations.

Mineral water is spring water that naturally contains at least 250 milligrams of dissolved minerals (like magnesium and calcium) per liter.

Sparkling water is spring water that contains carbon dioxide gas.

Drinking water is water that has probably been drawn from a municipal system. If the water comes right out of the tap and into the bottle or jug, the label has to disclose which municipality it came from. But if the water receives additional treatment — if it is filtered or disinfected before being bottled — no disclosure is necessary. That’s why you won’t find any mention on bottles of Pepsico’s Aquafina or Coca-Cola’s Dasani that both originate from city water supplies.

Purified water has been treated with distillation, ion-exchange, reverse osmosis, or another similar process.

Distilled water comes from the steam of municipal water that has been boiled. The process gets rid of most contaminants, but not benzene, chlorine, and some other volatile organic chemicals (some companies filter them out separately).

   In an analysis by the non-profit Natural Resources Defense Council (NRDC), about a dozen of the 103 brands of bottled water tested between 1996 and 1999 exceeded federal, state, or industry guidelines.1 Among the problem waters (which may or may not still be problems):

    Six store brands of drinking or purified water (Lady Lee, Ralph’s Private Selection, Publix, Randall’s Deja Blue, Safeway, and Sahara) and two store brands of spring water (Safeway and Sahara) contained between 16 and 92 ppb of total trihalomethanes (TTHMs).
    Four brands of mineral water (Apollinaris, Calistoga, Crystal Geyser, and Vittel) and three brands of spring water (Crystal Geyser, Palomaar, and Volvic) contained between 6 and 35 ppb of arsenic.

Short of testing it yourself, there’s no way to guarantee that your bottled water is free of contaminants. But you improve your chances if you stick to brands bottled by companies that are members of the International Bottled Water Association (IBWA). Their plants are open to unannounced inspections by NSF International, an independent certification agency .

1: “Bottled Water: Pure Drink or Pure Hype?” Natural Resources Defense Council, 1999.

^ Top

   A lot can happen on the way to the tap or bottle. Water can pick up healthy minerals like magnesium and calcium as it travels through rock formations. It can become laced with pesticides that are washed into rivers and streams. The chlorine that’s used to disinfect it can react with decaying leaves to form toxic byproducts. And even the purest water can become contaminated with lead from the pipes in your home.

   The Environmental Protection Agency (EPA) requires water utilities to keep the levels of 80 potential contaminants below legal limits. But even when water meets all regulations, it still may not be suitable for everyone to drink.

   On the whole, Americans have good clean drinking water. “You can travel the length of this country, drink the water at every stop, and probably never get sick,” says epidemiologist Rebecca Calderon of the Environmental Protection Agency (EPA). “But travel to many other countries and the story will be very different.”

   Indeed, almost 90 percent of the 55,000 public water systems in the U.S. report no violations of the EPA’s limits for drinking water contaminants.

   But that’s no guarantee that the water won’t make you sick.

   In two studies, Philadelphia water that met EPA standards appeared to increase gastrointestinal illnesses among children and the elderly.1,2 And in another study, California water that met EPA standards was linked to an increased risk of miscarriages.3

   How safe is your drinking water? To find out, you’re going to have to do a little detective work. First you need to know what to look for. Here are five of the most widespread or serious contaminants:

^ Top

Chlorinating water to destroy disease-causing bacteria was one of the greatest public-health achievements of the 20th century. But adding chlorine to water is a double-edged sword. The disinfectant can combine with decaying leaves and other naturally occurring organic matter to form compounds called disinfection byproducts (DBPs).

   “These byproducts are probably the most significant, most widely distributed contaminant in the U.S. water supply today,” says Kenneth Cantor, an epidemiologist at the National Cancer Institute in Bethesda, Maryland. “They can roughly double the risk of developing bladder cancer.”

   The EPA estimates that between two and 17 percent of all bladder cancer cases in the U.S. may be due to DBPs in drinking water. DBPs may also increase the risk of colon cancer, though the evidence isn’t as strong. Among 28,000 women in Iowa, for example, those who lived where the water had the highest levels of DBPs had nearly double the risk of colon cancer of those who lived where the water had the lowest levels.4

   And cancer’s not the only potential problem. In a 1998 study in northern California, pregnant women who lived where the tap water contained more than 75 parts per billion (ppb) of DBPs were nearly twice as likely to miscarry as women who lived where the tap water contained less than 75 ppb, but only if they drank at least five glasses of water a day.5 (The EPA’s limit for DBPs is 100 ppb. It’s scheduled to drop to 80 ppb beginning next year.)

   The link between DBPs and miscarriages is far from proven, though. In other areas of California, there didn’t seem to be any association. Researchers have just begun a study of 950 pregnant women to see if drinking water is linked to miscarriages in North Carolina, Texas, and Virginia.

^ Top

Is your tap water ever cloudy? That’s a sign of turbidity. Unfortunately, most of the time it’s not that obvious. Turbidity happens when particles of clay, silt, decaying plants, parasites, and other matter become suspended in the water. And it’s not just a cosmetic or taste problem.

  Disease-causing microorganisms can cling to the particles and escape destruction by chlorination and other disinfection methods. Public water utilities are supposed to remove the particles when turbidity becomes excessive, but that’s not always good enough. In 1993 in Philadelphia, for example, emergency room visits and hospital admissions for children with gastrointestinal illness increased by about ten percent whenever the turbidity of the city’s public drinking water increased significantly (but remained below the legal limit and wasn’t visible to consumers).1 And about ten days after the spikes in turbidity, hospital admissions of the elderly for GI tract illnesses increased by nine percent.2

   “These and other studies suggest that ten percent of gastrointestinal illnesses in children and the elderly may be due to turbidity in ordinary tap water at levels that pass federal standards,” says Joel Schwartz of the Harvard School of Public Health, who led both studies.

^ Top

About 40 million Americans drink water with excess lead, and that water accounts for about 20 percent of our exposure to the toxic metal, according to the EPA. Lead builds up in the body over many years and can damage the brain, kidneys, and red blood cells.

   Water can pick up lead almost anywhere along the way from the plant to the tap — in holding tanks, underground pipes, or lead pipes and fixtures inside old buildings or homes, especially those built before the 1930s.

   Although the use of lead pipes and solder was banned in public water systems and household plumbing in the 1980s, they may sometimes still be used illegally, says the EPA. Fortunately, a coating of minerals builds up inside the pipes after a few years, which helps keep the lead from leaching into the water.

^ Top

According to “Arsenic in Drinking Water,” a 1999 report by the National Academy of Sciences, the poison of choice of mystery writers can also cause cancer, heart disease, and perhaps diabetes.

   The EPA currently permits up to 50 ppb of arsenic in drinking water. But that standard was set 70 years ago, long before researchers discovered that the mineral can cause cancer. The World Health Organization recommends no more than 10 ppb.

   Congress has been pressuring the EPA for years to lower the arsenic limit.

   Arsenic-tainted water is most common in the Southwest and West. Some arsenic occurs naturally in soil, while some comes from industrial waste.

^ Top

Cryptosporidium (crip-toe-spo-RID-ee-um) is a parasite that lives in the intestines of humans and animals. When sewage or animal waste containing Cryptosporidium contaminates public water supplies, the results can be fatal.

   In 1993, for example, a breakdown in water sanitation in Milwaukee permitted Cryptosporidium to slip into the city’s drinking water for a week. A hundred people (mainly those with weakened immune systems) died, and 400,000 suffered the diarrhea, stomach cramps, and fever that are the hallmarks of cryptosporidiosis.

   Cryptosporidium is found in 65 to 97 percent of the nation’s surface waters (rivers, lakes, and streams), according to the Centers for Disease Control and Prevention (CDC). People who drink treated surface water — which provides about half of our tap water — are more likely to be exposed to the parasite than people whose tap water comes from underground rivers, streams, and other sources, according to a recent study.

   What makes Cryptosporidium so tough to control is that it’s small enough to pass through most filters (10,000 can fit on the period at the end of this sentence). And the parasite’s hard outer shell protects it from the chlorine that’s used to kill most microbes in water. Drinking-water regulations are designed to reduce — but not necessarily eliminate — Cryptosporidium, so even water systems that meet government standards may not be free of the parasite.

   What else might your drinking water contain? Everything from pesticides like atrazine to a possibly cancer-causing gasoline additive called MBTE. If that makes you nervous, here are three things you can do:

1. Epidemiology 8: 615, 1997.
2. J. Epidem. Comm. Health 54: 45, 2000.
3. Epidemiology 9: 126, 1998.
4. Amer. J. Pub. Health 87: 1168, 1997.
5. Epidemiology 9: 134, 1998.

See Also: Water Links
Nutrition Action Healthletter Subscribe Today! Customer Service