2026 Cobb County Water Annual Report

For Cobb County residents who have ever wondered what flows from the faucet, the 2026 Annual Water Quality Report shows that the drinking water distributed by Cobb County Water System met or exceeded federal and state drinking water quality requirements during testing conducted from January through December 2025.

The report explains where Cobb’s water comes from, how it is treated, what was found in the latest testing, and why the plumbing inside older homes can matter as much as the public water system outside the front door.

Where Cobb County Gets Its Water

Cobb County Water System does not treat its own drinking water. It purchases water wholesale from the Cobb County Marietta Water Authority, commonly known as CCMWA, then distributes that water to homes and businesses. CCMWA is the second largest wholesale water provider in Georgia.

CCMWA draws from two surface water sources:

• Lake Allatoona (feeding the the Hugh A. Wyckoff Water Treatment Plant on Mars Hill Road in Acworth)
• Chattahoochee River (feeding the the James E. Quarles Water Treatment Plant on Lower Roswell Road)

Combined, the two plants can produce up to 172 million gallons of drinking water per day. From there, Cobb County Water System distributes water through a large network that includes roughly 3,100 miles of water mains, more than 27,500 fire hydrants, and more than 900,000 residents.

That scale is easy to miss. A glass of water at the kitchen sink is the end point of a regional system tied to two major water sources, two treatment plants, storage tanks, transmission lines, neighborhood mains, service lines, and household plumbing.

Is Cobb County’s Water Safe?

Yes. The 2026 report says the water provided by CCMWA and distributed by Cobb County Water System met or exceeded all federal and state drinking water quality requirements for the 2025 testing period.

The supporting testing data shows strong results in several areas. Finished water at the treatment plants showed 0 percent positive results for total coliform and E. coli. Many inorganic chemicals, including arsenic, barium, cadmium, mercury, selenium, and thallium, were listed as not detected in the 2025 testing data.

Fluoride was detected at low levels, with averages of 0.71 milligrams per liter at Quarles and 0.66 milligrams per liter at Wyckoff, below the federal maximum contaminant level of 4.0 milligrams per liter. Nitrate and nitrite were also below the federal limit.

Disinfection byproducts were detected, as expected in a treated drinking water system, but the reported levels met EPA limits. These byproducts form when disinfectants react with natural organic matter in source water. That is a normal part of modern drinking water chemistry, and it is regulated because the balance between disinfection and byproduct control is important.

Cobb’s Water Is Relatively Soft

One useful detail in the testing data is water hardness. CCMWA reported hardness of 1.9 grains per gallon at Quarles and 2.1 grains per gallon at Wyckoff.

That puts Cobb’s treated water in the soft water range. For homeowners, soft water generally means less mineral scale on faucets, showers and showerheads, water heaters, dishwashers, and coffee makers than areas with hard well water or high mineral groundwater.

It is a small detail, but it explains a lot about daily life with Cobb tap water. The water is not mineral heavy, and that can affect everything from appliance buildup to how soap rinses.

Lead And Copper: The System Passed, But Older Homes…

The lead and copper results are one of the most important parts of the new report, especially for owners of older homes.

CCMWA conducted lead and copper sampling from June through September 2025. The 90th percentile lead result was 2.9 parts per billion, below the federal action level of 15 parts per billion. The 90th percentile copper result was 0.078 parts per million, below the action level of 1.3 parts per million.

Those numbers show compliance. They do not mean every faucet in every home has the same result.

The individual lead samples ranged from 0 to 37 parts per billion. Most samples were at or near zero, but a small number came in higher, including 14, 24, and 37 parts per billion. That is where the report can become more personal for homeowners.

Lead in tap water usually does not come from the source water or the treatment plant. It usually enters water after treatment, when water passes through service lines, interior pipes, solder, valves, faucets, and fixtures that contain lead or materials that can release lead.

Cobb County has reported that no lead or galvanized lines requiring replacement have been identified in the Cobb County Water System service area, which includes most of unincorporated Cobb County and the cities of Acworth, Kennesaw, Powder Springs, and Mableton. The county says all service lines in its inventory are classified as non lead.

That is good news. It also has a limit. The service line inventory does not mean every older faucet, fixture, solder joint, or interior pipe inside every private home is free of concern.

What Owners Of Older Homes Should Do

Owners of homes built before 1986 should pay close attention. The EPA says lead pipes are more likely in older cities and homes built before 1986. In homes without lead service lines, lead can still come from brass or chrome plated brass faucets and plumbing with lead solder.

For older homes, the best first move is testing water at the tap. Lead dissolved in water cannot be seen, smelled, or tasted. A clear glass of water can still contain lead, and a countywide report cannot answer what is happening at one specific kitchen sink.

UGA Cobb Extension offers water testing services and notes that municipal water concerns in Cobb County often occur after water has entered the home. That makes local tap testing useful for older homes, homes with plumbing concerns, and homes with infants, young children, or pregnant women.

Residents can also check Cobb County’s Water Service Line Inventory and use the county’s service line material reporting tool to document the pipe material entering the home. The county says this can often be checked in a crawlspace, basement, or garage.

Several daily habits can reduce risk:

• Use cold tap water for drinking, cooking, brushing teeth, and preparing baby formula.
• Do not use hot tap water as a cooking shortcut. Hot water can pick up more metals and sediment from household plumbing and water heaters. For coffee, tea, pasta, soup, or baby formula, start with cold water and heat it in a kettle, pot, or microwave.
• Run the cold tap after water has been sitting in pipes for several hours. This is especially useful first thing in the morning or after returning from a trip. The time needed can vary by house and plumbing layout.
• Clean faucet aerators regularly. Sediment and particles can collect in the screen at the end of a faucet.
• Use a filter certified to reduce lead if there is a concern, and replace the cartridge on schedule. A filter past its service life is not reliable protection.
• Ask a plumber to inspect older visible plumbing, older fixtures, and the pipe entering the home during other repair or renovation projects.

Boiling water does not remove lead. It can make the problem worse by concentrating metals as water evaporates.

PFAS: Low Levels, But Worth Watching

The 2026 report also includes PFAS monitoring. PFAS, often called forever chemicals, are synthetic compounds used in many consumer and industrial products. They persist in the environment and have become one of the major water quality issues nationwide.

CCMWA’s 2025 data showed several PFAS compounds at very low parts per trillion levels. PFOA had a highest detected level of 3.2 parts per trillion, and PFOS had a highest detected level of 3.0 parts per trillion. Both are below EPA’s 4 parts per trillion maximum contaminant level for each compound.

Other PFAS compounds were also reported at low levels, including PFBS, PFBA, PFPeA, and PFHxA. CCMWA says its current results show PFOA and PFOS have generally been detected in the 2 to 3 parts per trillion range, below EPA limits, and that its calculated Hazard Index has remained well below the regulatory limit.

For residents, the important point is that the report does not show a PFAS emergency. It does show why PFAS will remain one of the most important items to watch in future water quality reports as federal monitoring and compliance requirements continue to develop.

Taste And Odor Can Change Without Making Water Unsafe

The report also helps explain why water can taste or smell different even when it meets safety standards.

CCMWA has reported elevated MIB, also known as 2 methylisoborneol, at the Quarles plant. MIB can cause an earthy or musty taste and odor. CCMWA reported that Chattahoochee River source water reached 137 parts per trillion of MIB in November 2025, compared with 19 parts per trillion as the highest level recorded in 2024.

CCMWA said those MIB levels presented no health concern and that the drinking water remained safe. Still, taste matters. For residents who notice an earthy taste or odor, CCMWA has said chilling water, using an activated carbon filter, or adding lemon juice can help.

Potable Water And Hot Tap Water

Potable water means water that is safe to drink. Cobb County’s treated drinking water meets the applicable standards.

Hot tap water should still be avoided for drinking and cooking, especially in older homes. The hot water line is fed by the same water supply, but water that has passed through a water heater and hot side plumbing can contain more sediment or metals from household materials.

The safest routine is simple: use cold water from the tap for drinking, cooking, and food preparation, then heat it separately.

The Bottom Line

Cobb County’s 2026 Water Quality Report is favorable. The system passed required testing, finished water bacteria results were clean, PFAS levels were reported at low concentrations, and lead and copper results met federal action levels.

The most important lesson is that water quality has two sides. The public system can meet standards, while an individual home can still have older plumbing, older fixtures, or stagnant water that changes what reaches the faucet.

For most residents, the report is reassuring. For owners of older homes, it is a reminder to test the tap, use cold water for consumption, clean aerators, consider certified filtration, and know what materials are inside the house.