Before coming out of your tap, raw water undergoes a thorough treatment process. This process eliminates contaminants and ensures your water is safe and good-tasting. The treatment begins when raw water is moved from Carter Lake to the Carter Lake Filter Plants. Certified plant operators manage the treatment process, evaluating water quality throughout treatment. Water moves through the treatment plant in five stages:

1. Coagulation Flocculation: Raw water flows into our treatment plants where coagulants, polymers and chlorine dioxide are added to cause small particles to stick to one another. The larger particles are easier to filter out.
2. Filtration: Depending on the treatment plant, the water is then filtered through membranes or fine layers of filter media.
3. Disinfection: Following filtration, chlorine is added to protect against viruses, bacteria and other micro-organisms. The amount of chlorine added is carefully monitored, and any remaining chlorine levels are monitored continuously.
4. Fluoridation: Fluoride occurs naturally in source water. To meet the recommended health levels,  fluoride is added to the treated water since it is removed during the treatment process. Due to global supply chain issues, Carter Lake Filter Plan may intermittently add fluoride to the water.
5. Corrosion Control: Soda ash and/or sodium hydroxide maintain pH. A corrosion inhibitor reduces the corrosiveness of drinking water.

Once water is "finished" or treated, it is conveyed to LTWD’s distribution system. LTWD performs additional water quality tests at locations throughout the distribution system. We also test water taps in customer homes and businesses. Annual system flushing also helps ensure water quality by reducing sediment in the system’s pipes and ensuring chlorine residual is maintained. In the spring, we open fire hydrants, which allow water to flush the pipes at high pressure and also enables us to check the system capacity to provide fire protection.

Here are some of the common questions and concerns we hear from customers  regarding water quality:

• Dirty Water: Occasionally, "dirty" or discolored water may appear when you turn on the faucet at your home or work. Discolored water usually comes from the water distribution system or your home's or business's private plumbing. Your home's plumbing, including the water heater, may also be a source of discolored water. Please call our office for assistance if you have dirty or discolored water at the tap.
• Taste and Odor: Typically, LTWD’s water is both tasteless and odorless or has minimally perceived taste and odor. However, water can get an odd taste or odor from our source water streams and reservoirs. It can also occur in the treatment process or in the distribution system. Learn more about taste and odor in water on our FAQs page, email us or call our office with your questions or concerns.
• Disinfection Byproducts: Water disinfection is a necessary part of the water treatment process. Disinfection destroys microbes, bacteria and viruses. There is a possibility that microorganisms might get into treated water after it leaves the treatment plant. Because of this, public health regulations require that tiny but detectable amounts of disinfectant must remain in the water all the way to the tap. We follow all EPA regulations regarding drinking water quality, including safe levels of microorganisms, disinfectant and disinfection byproducts.
• Fluoride: Fluoride is a naturally occurring compound in the District’s source water. It enters the water when fluoride-rich minerals dissolve into raw water. As flouride is remove through the treatment process, we add fluoride to the water during the treatment process to meet the State’s recommended level of 0.7 milligrams per liter. Fluoride in water helps promote dental health and prevent tooth decay.
• Lead: Lead is a naturally occurring metal used for many years in paints, plumbing and other products found in and around homes. The EPA has determined that lead can cause health problems if it adds up in a person’s body over time. Lead is especially hazardous for children and pregnant women. Customers can have their water tested through an independent testing facility. Contact the testing facility for specific tests and associated fees. Customers are responsible for all associated fees. Learn more about lead testing.
• Trace Pharmaceuticals: Trace pharmaceuticals are sometimes called microconstituents or emerging contaminants. They can come from agricultural runoff as well as human sources, including when people dispose of medicines in the sink or toilet. Most pharmaceutical products used in animals or humans pass through the user and return trace levels into the water system. Carter Lake Filter Plant can detect more substances at lower levels thanks to improving technology. As technology improves, pharmaceutical compounds and personal care products are being found at very low levels in many of our nation's lakes, rivers and streams. Carter Lake Filter Plant does not currently monitor trace pharmaceuticals. However, monitoring may occur in the future.
• Water Hardness: Hardness in water comes from calcium and magnesium concentrations (salts), expressed as calcium carbonate. The hardness of the water varies with the amounts of these salts. These components enter water when underground and surface waters absorb minerals. Hard or soft water are not a health concern. However, hard water may have a mineral taste. Soft water may have a flat, unpleasant taste. The average total hardness of LTWD’s finished water is approximately 32.00 mg/L. This is classified as soft.