Use a Carbon Filter System for Safe Drinking Water

How to test your drinking water, and if it's polluted, why you should use a carbon filter system for safe drinking water.
June/July 2003
Use a carbon filter system for safe drinking water, such as this point-of-use activated-charcoal water filter.


Learn why you should use a carbon filter system for safe drinking water.

The United States enjoys one of the safest water supplies in the world, but you'd never know it judging by the number of us slogging bottles of designer water with us everywhere we go. Given that Americans shell out more than $7 billion each year for bottled water products, it's safe to say that some of us plunking down our money are just plain skeptical about what's coming out of the tap at home.

Recent newspaper headlines offer little reassurance: microscopic critters sending people to emergency rooms, fertilizers and factory-farm manure seeping into ground water, lead leaching from pipes in older homes, recent reports that researchers are finding traces of pharmaceutical drugs in our water supplies . . . small wonder that turning on the faucet can sometimes seem like a game of Russian roulette.

The long-term consequences of drinking water containing traces of so many chemicals are almost impossible to determine. "The impacts of our continual exposure to a multitude of toxicants at low or trace doses is a hotly debated issue," says Christian Daughton, Ph.D., chief of the U.S. Environmental Protection Agency's Environmental Chemistry Branch in Las Vegas. His research on pharmaceutical drug residues in the environment has helped bring the issue to the forefront. But remember, he says, not all water problems are human-made. "There's a universe of naturally occurring chemicals, many of which have their own profound toxicity."

Because our bodies are 50 percent to 65 percent water (children's bodies are about 75 percent water), it certainly makes sense to try to drink water that's as free from harmful contaminants as possible. Many people have sought to protect themselves by switching from tap to bottled water, but this can be expensive and inconvenient, and the improvement in quality is debatable (See "Is Bottled Better Than Filtered Water?" page 70 in this issue). Depending on what contaminants you need to remove, a range of home water-treatment options is available; all of them are much cheaper over time than buying bottled water.

In order to find out which system is right for you, you'll need to find out what's in your water. If you're connected to a public water supply, you can obtain a copy of your municipality's Consumer Confidence Report by visiting the website (click on Local Drinking Water Information). Public water suppliers are required by federal law to provide consumers with information on where the water comes from and whether the water exceeds the limits for any of the 80 contaminants regulated by the EPA. You also can request a printout of the levels of all the regulated chemicals. People on private wells can visit the EPA's Safewater Web site to locate state-certified water testing labs. Local health departments and cooperative extension offices may offer low-cost testing for certain problems.

Water Contaminants

Federal law requires municipal water supplies to be monitored to be sure regulated contaminants do not exceed legal limits. In older homes, lead is a concern, as it may leach into water on its way to the tap. Chlorine, commonly used to help disinfect water, brings along its own host of health concerns.

People on private wells don't enjoy the benefit of having someone else monitoring contaminant levels in their water, so they must be diligent about testing it themselves and maintaining their wells. Nitrates and bacteria are by far the most common pollutants in private systems. "We view nitrate contamination as a signal that there also may be a bacterial problem," says Rhonda Janke, an agronomy extension specialist at Kansas State University in Manhattan, Kansas. High levels of nitrates and/or bacteria indicate that you have a plume of pollution seeping into your well, possibly from a local farm or industrial area. "Look uphill; look upstream," says Janke. "Anything that's above your well has the potential to run into it, even if it's a mile or two away."

Water Bacteria, Cysts and Other Disease-Producing Organisms

Many different types of microbes can be found throughout our environment, some friendly, some problematic, and water is no exception. Although many types of bacteria do not cause disease themselves, their presence may signal a more serious problem. Coliform bacteria, a group of bacteria commonly found in animal digestive systems (including humans), usually do not cause disease, but their presence suggests that fecal matter from sewage or animal waste is finding its way into your water supply.

Certain types of coliform, particularly such toxic strains as E. coli 0157:H7, can cause serious, even life-threatening, illness in children and people with depressed immune systems. Most often though, drinking bacteria-laden water causes fever, gastrointestinal illness and other flu-like symptoms.

Giardia lamblia and Cryptosporidium parvum are microscopic protozoa that are carried into water supplies from animal fecal material, too. Typical symptoms of infection include severe diarrhea, nausea, fever, headache, vomiting and loss of appetite.

These organisms are rarely a problem with respect to private water supplies fed from underground water sources, because rocks and soil naturally filter out the eggs (called oocysts) as the surface water percolates down through the ground. Most often, outbreaks of these organisms occur in municipal water supplies sourced from surface waters such as lakes and rivers. Shallow springs and poorly constructed wells also are vulnerable to protozoa infection

Finding the Right Water Filtering Solution

The good news is that for most of us, the solution to our water problems is simple: An inexpensive carbon filter can improve taste, and can remove chlorine and other common organic contaminants. If you suspect you may have a more serious problem, be sure to have your water tested. People on private systems should have their water tested at least yearly for bacteria and nitrates.

Once you've determined what contaminants you need to remove, choose a filter that meets your needs. Many manufacturers have their water treatment products tested by the National Sanitation Foundation, a nonprofit organization that tests water treatment devices to ensure they remove the toxicants their makers claim they do.

Whatever system you choose, be sure to maintain it according to the manufacturer's directions. Poorly operating filters may cause more problems than they solve.

Here's our rundown of the common types of water treatment systems you'll find on the market. Look for these products in hardware stores and home-improvement centers, or also online. You'll find a particularly good selection of filters at

Carbon Filter System for Safe Drinking Water

If you simply want to improve the taste of your water by removing chlorine and its byproducts, an activated-carbon pour-through carafe or faucet-mounted filter may be all you need. Some carbon filters also will remove lead, asbestos, cysts, solvents, gasoline and pesticides. Extremely porous with a large surface area, activated-carbon filters work by adsorption: As the water passes through the filter, contaminants bind to the surface of the carbon. The carbon also chemically converts chlorine into safer chloride and hydrogen ions.

In carafes, water flows from the upper chamber through a carbon filter and into a serving pitcher. Faucet-mounted units screw directly onto the faucet — a turn of the valve diverts water into the filter when drinking water is needed, then back through the faucet for washing dishes and filling buckets.

Priced between about $10 and $40, activated-carbon devices are the least expensive option for home-water treatment — although you can expect to pay up to twice that initial investment annually for replacement cartridges.

Though their price and versatility may be appealing, carbon filters need to be changed regularly or they can actually become a source of contaminants. Bacteria feed on organic matter that accumulates on the surface of the carbon. If the filters aren't changed regularly, these bacteria can make their way into the water supply.

Both carafes and faucet-mounted carbon filters can be somewhat slow to actually get their filtration jobs done, especially as the filter nears the end of its useful life.

Point-of-Entry Water Filters

Sometimes called sediment filters, these units are plumbed into the system where water service enters the house. These filters usually trap large particles of sand, dirt or mineral contaminants and treat all of the water used in the house. Prices range from about $50 to $200.

Point-of-Use Water Filters

Countertop/Faucet. These filtering units are mounted on or below the counter and are connected to the faucet through tubing. A valve diverts water into the unit when you want to filter water. Most units reduce chlorine byproducts, lead and parasites; the better models also will remove chemical contaminants and certain pesticides. Expect to pay about $120 to $140 for one of these units. You may need a plumber to help install it.

Reverse-osmosis filters are considered by many to be the most sophisticated homewater treatment option. "Reverse osmosis filters remove the broadest spectrum of chemicals from water as well as give the highest removal rates," says the EPA's Daughton. Reverse osmosis filters reduce a wide range of contaminants including chlorine byproducts, many pesticides, lead, nitrates, bacteria and other microorganisms. (Parents should be aware that many of these filters also remove fluoride.) The process involves forcing water through very fine membranes small enough to trap molecules of pollutants, but large enough to allow the water to pass. It's a slow process that produces just a few gallons of water at a time, which are typically stored in tanks below the sink.

The main disadvantage of these filters is that they waste from 3 to 10 gallons of water for every gallon of filtered drinking water produced. "Reverse osmosis filters suffer from the same problem that all the other systems suffer from," says Daughton. "Without proper maintenance, the system will eventually fail, and sometimes this eludes the user's notice." Expect to pay about $200 to $400 for a reverse-osmosis unit, which must be professionally installed.

Distillation . Although distilled water has long enjoyed the reputation of being the purest of pure among waters (although Daughton says distillation units cannot rival reverse osmosis for effectiveness in removing volatile chemicals), achieving proper distillation at home can be somewhat trickier than it is in a large commercial setting. Distillation is great for removing nitrates, bacteria and microorganisms, and metals such as iron and lead.

During the purification process, water is boiled in a chamber and vaporized. Then, the vapor is condensed onto coils. The condensed liquid water flows to a separate storage chamber.

Although distillation removes a wide variety of contaminants, certain compounds such as benzene and toluene have a lower boiling point than water and will vaporize right along with it. If these products are not removed before condensation occurs, their levels may actually increase.

Small countertop electric distillers cost from about $150 to $350, but because so much energy is required to heat the water, distillers can be among the most expensive water-treatment systems to operate.

To find out how you can utilize the sun's energy to radically reduce these costs, see our article on solar distillers in the August/September 2002 issue, online in MOTHER'S new Archive at Expect to pay about $400 to $800 for a solar water distiller.