Frequently Asked Questions

We treat water from the Edisto River and the Bushy Park Reservoir, both of which are surface water sources. The water is treated at our Hanahan Water Treatment Plant, which is permitted to treat up to 118 million gallons per day (mgd).

How is my water disinfected?
Charleston Water System uses a combination of chlorine and chloramines (a chemical formed by combining ammonia and chlorine) to kill harmful bacteria and viruses in the water. Chloramines are more stable than chlorine in the water distribution system, and chloramine residuals help maintain consistent water quality. The amount of chemicals is carefully measured to the lowest level needed to keep the water free of disease-causing organisms.

>Learn more about the water treatment process

Sometimes my water looks "milky white." What causes this and is it safe to drink?
This is a temporary and harmless condition called aeration, which is air dissolved in water. If you let a glass of water stand for several minutes the air bubbles will rise to the top, and the water will become clear.

>Learn more about water quality

Does Charleston Water System water contain fluoride?
Yes. Charleston Water System adds one milligram per liter (mg/1) or one part per million (ppm) of fluoride to treated water. This is the amount recommended by the American Dental Association to provide maximum protection from tooth decay.

>See our Water Quality Reports

What is hardness and how hard is my water?
Hardness is a measure of the amount of calcium and magnesium minerals in water. Groundwater typically has a higher mineral content than surface water. A high concentration of minerals in the water can make it hard to lather, hence the term “hard water.” Soft water, on the other hand, has a low concentration of minerals, and requires extra rinsing to remove soap. Our water is moderately soft, with 65 milligrams per liter of hardness.

What is pH?
The pH of the water is a measure of the water's acidity on a scale of 0 (acidic) to 14 (basic), with a pH of 7 being neutral. For example, the pH of vinegar is 2.2 (acidic) and the pH of seawater is 8.3 (basic). The pH of Charleston Water System water is adjusted to stabilize the disinfectant and to reduce the corrosion of pipes and plumbing materials.

Is my water safe to drink? Is bottled water or filtered water safer?
Yes, Charleston Water System tap water is safe to drink. Bottled or filtered water is very costly compared to tap water and there are no guarantees that you are getting higher quality water. In fact, a recent study conducted by researchers at the University of California at Berkley (funded by EPA and the Centers for Disease Control) found no additional health benefit from using in-home tap filters, called point-of-use (POU) devices. Furthermore, with respect to bottled water, the industry is less regulated than municipal drinking water. Charleston Water System water meets or exceeds all federal and state drinking water standards.

My water tastes/smells funny. Does this mean it's not safe to drink? What should I do?
There are a variety of factors that can impact the taste or smell of tap water but not change the quality of the water. In Charleston Water's case, algae in our surface water—when put through the treatment process—can give off harmless compounds that may cause the water to taste “earthy” or “musty.” In most cases, taste and odor are purely aesthetic concerns, and are not reliable indicators of water quality.

I live in an older home, should I be concerned about lead pipes contaminating my water?
Lead does not occur naturally in Charleston Water System drinking water, nor is it a result of the treatment process. Chances are your home's water supply does not contain lead; however, if your home was built prior to 1930 or in the 1980s, the interior plumbing system may include lead pipes or copper pipes connected with lead solder. In the past, lead may have leached into the water, but Charleston Water System now adds a corrosion inhibitor to water during the treatment process, which bonds with lead and forms a protective molecular coating that prevents leaching. If you are concerned about lead in your water, Charleston Water System will test your water free of charge. Just stop by one of our Customer Service locations to pick up a testing kit.

>Learn more about lead

Should I be concerned about the sodium level of Charleston Water System water?
No. Our water has a very low sodium level (10mg/1 or less). This is substantially lower than most well water supplies and many bottled water brands.

Why does my water sometimes appear rusty?
Discolored water may occur when crews perform maintenance on a water main near your home. A change in water velocities can cause the iron compounds that accumulate in water mains to become suspended in the water. This is a temporary condition and is harmless. Typically, allowing your tap to run will flush out the discolored water and clear water will appear.

Is tap water safe for use in aquariums?
No. Charleston Water System uses chloramines (a mixture of chlorine and ammonia) to disinfect drinking water, which are harmful to fish and other aquatic life. There are a number of products available at pet stores to remove chloramines from your fish tank. Charleston Water System tap water is safe for dog, cats, and other non-aquatic pets.

What is a Boil Water Advisory?
If the public water system becomes contaminated or a situation allows the possibility of contamination (such as a water main break or loss of system pressure), Charleston Water System will issue a Boil Water Advisory. The Department of Health and Environmental Control requires the issuance of a Boil Water Advisory under certain conditions, such as loss of system pressure. During an advisory, customers should bring water to a vigorous boil for at least one minute before use. This will kill any harmful organisms that may be in the water. Click here for more information.

Should I be concerned about Cryptosporidium or Giardia?
No. Charleston Water System has extensively monitored for both protozoan organisms in both its Edisto and Cooper River sources of supply, and there is a very low occurrence of these pathogenic organisms. Furthermore, the treatment plant has multiple barriers of protection such as enhanced chemical coagulation, filtration, disinfection, and careful monitoring of turbidity to ensure the optimum removal of these organisms. However, for people with compromised immune systems, the EPA and the US Center for Disease Control offer the following advisory statement:

Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised persons such as persons with HIV/AIDS or other immune system disorders, persons with cancer undergoing chemotherapy, persons who have undergone organ transplants, some elderly and some infants can be particularly at risk from infections. These people should seek advice from their health care providers. EPA/CDC guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the Safe Drinking Water Hotline at 1-800-426-4791.

I've heard about some cities out west where the shortage of water is a serious concern; is water supply a problem in Charleston?
No, Charleston Water System has an abundant water supply, but that doesn't mean you shouldn't conserve water. Water is a valuable resource and wasting it costs you money. Besides, it takes very little effort to practice water conservation.

I’ve heard that you shouldn’t drink or cook with hot water from the tap. Is this true?
Yes, you should always use the cold water faucet for drinking, cooking, and especially for mixing infant formula. Hot water from the tap comes from your hot water heater, and it may contain impurities. Also, if you have plumbing with lead solder or brass fixtures (which contain lead), the lead is more likely to leach into hot water than cold water. Instead of using the hot water tap, heat cold water on the stove or in the microwave.

My dishwasher leaves water spots on my glasses. What can I do to prevent this?
Those “water spots” on dishes are precipitates, or minerals in the water that are left behind when water evaporates. To prevent this, use a rinsing agent such as JetDry, which improves the sheeting action of water and helps to prevent spotting. Also, be sure to use the proper amount of dishwashing detergent. Using too little may not get your dishes clean, and using too much can cause etching, which is tiny scratches on the surface of the glass that cannot be removed. The amount of dishwashing detergent to use depends on the hardness of water, or the amount of minerals in the water. For CPW water, use between one and two tablespoons of detergent.

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