Where does Charleston Water System water come from?
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 the water disinfected?
Charleston Water System uses chlorine dioxide and chloramines (a compound 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 disinfectant 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's water contain fluoride?
Yes. Charleston Water System’s water has ~0.15 mg/L of naturally occurring fluoride, and we add ~0.6 mg/L during the treatment process for a total of ~0.7 mg/L of fluoride in our drinking water, in accordance with recommendations from the American Dental Association, Centers for Disease Control, and other health organizations to promote dental health.
More about fluoride
Annual water quality reports
What is hardness, and how hard is Charleston's water?
Water hardness is a measure of dissolved minerals in water, specifically calcium and magnesium. Soft water has little or no dissolved minerals. Hard water has higher mineral content that can cause scaling in plumbing and soap scum residue in bathrooms.
Charleston Water System has moderately soft water. Our lab measures hardness in parts per million (ppm), but it can also be expressed in grains per gallon (gpg). The average hardness level of our water is 58.4 ppm, or 3.4 gpg, as shown in the chart below.
Some dishwashers and washing machines have hardness-related settings or recommend how much detergent to use based on your water's hardness.
Charleston Water hardness level of 3.4 gpg is a 5-year average (2007 – 2011).
1 grain per gallon = 17.1 parts per million (ppm)
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 Charleston's water, use between one and two tablespoons of detergent.
What is the pH of Charleston's water?
The pH of 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. The pH of Charleston's water is adjusted to around 8.3. This helps 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 meets or exceeds all drinking water standards and is safe to drink. Bottled or filtered water is also high quality, but it is much more expensive than tap water.
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?
Although the most common lead exposure is by swallowing or
breathing in lead paint chips and dust, lead can leach into tap water by corrosion of plumbing materials.
Homes built before 1986 are more likely to have lead pipes, fixtures and solder, but even new plumbing materials may legally contain up to 8 percent lead.
To minimize this corrosion of lead into water, Charleston
Water System adjusts the properties of our water to inhibit
the chemical reaction that causes lead to leach into water
As an extra precaution, you can minimize the potential for
lead exposure by flushing out water that has been sitting in
your home's plumbing for several hours or more. Just let
your water run for up to two minutes before using it for
cooking or drinking.
Charleston Water System offers free lead tests. You can pick
up a testing kit at our office locations: 103 St. Philip Street,
Downtown, and 6296 Rivers Avenue, North Area. For
more information about lead, visit the USEPA's web site.
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 the direction or velocity of water flow water can cause the iron compounds that accumulate in water mains to become suspended in the water.
Typically, our crews will open a nearby fire hydrant to flush out this discolored water before it reaches customers' taps. But, if you experience discolored water, you can flush your plumbing by turning on a faucet until the water runs clear. If it persists, call us at (843) 727-6800.
Is tap water safe for use in aquariums?
No. Charleston Water System uses chloramines (a combination of chlorine and ammonia) to disinfect drinking water, and chloramines 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 SC Department of Health and Environmental Control (SCDHEC) requires the issuance of a Boil Water Advisory under certain conditions, such as widespread loss of system pressure or a large water main break.
If an advisory is issued, we will notify customers via the media. During an advisory, customers should bring water to a vigorous boil for at least one minute before use. This will kill any bacteria that may be in the water.
Learn more about boil water advisories
Should I be concerned about Cryptosporidium or Giardia?
No. Charleston Water System has extensively monitored for both organisms in our source water, and there is a very low occurrence of these pathogenic organisms.
In addition, our 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.
Does Charleston have a shortage of water?
No, Charleston Water System has an abundant water supply, even during a drought. However, water is a valuable resource, and we encourage everyone to use it wisely.
Is it okay to use the hot water tap for cooking or drinking?
Yes, you should always use the cold water faucet for drinking, cooking, and especially for preparing infant formula.
Hot water from the tap comes from your water heater, which 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.