Water Softeners & Whole-Home Filtration in Cobb County, GA
Most Cobb County homes get treated water from Lake Allatoona and the Chattahoochee River through the Cobb County-Marietta Water Authority. It is low in hardness (about 2 grains per gallon), carries chlorine up to about 2 ppm, and every listed utility reported no health-based violations. For city water we recommend carbon filtration first with softening as the finish — our Complete Home Package — and for wells, the Dual Tank — Well Water plus UV after a lab test.
Your water in Cobb County
Almost every public system in Cobb County traces back to one wholesaler: the Cobb County-Marietta Water Authority, which treats water from Lake Allatoona at its Wyckoff plant and from the Chattahoochee River at its Quarles plant. Cobb County Water System, Marietta Water, Austell and Smyrna all distribute that water, which is why the hardness and PFAS figures below look so similar. Where they differ is in the disinfection byproducts measured out in each distribution system, because those form as chlorinated water travels through the pipes. All figures are copied from each utility's own annual report.
Cobb County Water System
- Serves
- Unincorporated Cobb County plus Mableton, Acworth, Kennesaw and Powder Springs
- Source
- Lake Allatoona and the Chattahoochee River, treated by the Cobb County-Marietta Water Authority
- Hardness
- 1.9–2.1 gpg
- Chlorine
- 2.00 ppm highest (range 0–2.00)
- Trihalomethanes (TTHMs)
- 60 ppb (highest running average, site 513) vs federal limit 80 ppb
- Haloacetic acids (HAA5)
- 37 ppb (highest running average, site 504) vs federal limit 60 ppb
- Lead
- 2.9 ppb (90th percentile, 2025, from sampling pooled across the Water Authority's customer systems; 2 of 50 samples above 15 ppb) vs action level 15 ppb
- PFAS
- PFOA 3.2 ppt, PFOS 3.0 ppt (highest, 2025 testing at the treatment plants)
- Violations
- No health-based violations. A 2025 monitoring notice at the wholesaler: radionuclide samples were lost in shipping and re-collected.
Marietta Water (City of Marietta)
- Serves
- City of Marietta customers
- Source
- Buys all its water from the Cobb County-Marietta Water Authority (Chattahoochee River and Lake Allatoona)
- Hardness
- 1.9–2.1 gpg
- Chlorine
- 2.00 ppm highest (range ND–2.00)
- Trihalomethanes (TTHMs)
- 36.1 ppb (highest running average) vs federal limit 80 ppb
- Haloacetic acids (HAA5)
- 28.4 ppb (highest running average) vs federal limit 60 ppb
- Lead
- 2.9 ppb (90th percentile, 2025, from sampling pooled across the Water Authority's customer systems; 2 of 50 samples above 15 ppb) vs action level 15 ppb
- PFAS
- PFOA 3.2 ppt, PFOS 3.0 ppt (highest, 2025)
- Violations
- No health-based violations. One monitoring violation at the wholesaler (radionuclide samples lost in shipping; re-collected March 2026).
Source: Marietta Water (City of Marietta), 2025 water quality report
Austell Water System
- Serves
- City of Austell
- Source
- Buys from the Cobb County-Marietta Water Authority (Lake Allatoona and the Chattahoochee River)
- Hardness
- 1.9–2.1 gpg
- Chlorine
- 2.0 ppm (range 0–2.00)
- Trihalomethanes (TTHMs)
- 52.4 ppb (highest running average) vs federal limit 80 ppb
- Haloacetic acids (HAA5)
- 38.43 ppb (highest running average) vs federal limit 60 ppb
- Lead
- 90th percentile not printed; range 0–37 ppb, 2 sites above 15 ppb (2025) vs action level 15 ppb
- PFAS
- Not reported
- Violations
- None reported.
Cobb County-Marietta Water Authority (Smyrna and others)
- Serves
- Water treated by the Cobb County-Marietta Water Authority (wholesaler to Smyrna, Mountain Park and others)
- Source
- Lake Allatoona (Wyckoff plant) and the Chattahoochee River (Quarles plant)
- Hardness
- 1.9–2.1 gpg
- Chlorine
- 1.8 mg/L average leaving both plants
- Trihalomethanes (TTHMs)
- 36.1 ppb (highest running average, the Water Authority's 2025 table) vs federal limit 80 ppb
- Haloacetic acids (HAA5)
- 28.4 ppb (highest running average, same source) vs federal limit 60 ppb
- Lead
- 2.9 ppb (90th percentile, 2025, from sampling pooled across the Water Authority's customer systems; 2 of 50 samples above 15 ppb) vs action level 15 ppb
- PFAS
- PFOA 3.2 ppt, PFOS 3.0 ppt (highest, 2025)
- Violations
- No health-based violations; one 2025 monitoring notice (lost radionuclide samples).
Source: Cobb County-Marietta Water Authority (Smyrna and others), 2025 water quality report
Federal limits: TTHMs 80 ppb and HAA5 60 ppb (running annual averages); lead action level 15 ppb at the 90th percentile.
City water vs. well water in Cobb County
On Cobb County public water, hardness is not the main story. At roughly 1.9–2.1 grains per gallon, the Water Authority's water is soft by most standards. What most households notice is chlorine: taste and smell at the tap, and dry skin and hair in the shower. Chlorine also reacts with natural organic matter to form trihalomethanes and haloacetic acids. Cobb's utilities reported those within federal limits, but carbon filtration is built to reduce them further. That's why we put carbon first and treat softening as the finish — it adds scale protection for your water heater and fixtures rather than fixing a hardness problem.
Wells are a different case. Parts of west and north Cobb still have private wells, and well water commonly carries iron, manganese and a sulfur (rotten-egg) smell. It also has no disinfectant in the line at all. For a well we recommend the Dual Tank — Well Water paired with a UV purifier, and we always suggest a certified lab test of the well first so the system is sized to what's actually in your water.
Systems we recommend here
For most homes on Cobb County, Marietta, Austell or Smyrna water, the Complete Home Package ($2,599) is our first recommendation: whole-house carbon filtration and softening, plus the HW800 AlkaPro Tankless RO ($999 on its own) for drinking and cooking water at the kitchen sink. On a private well, the Dual Tank — Well Water ($3,499) is built to reduce iron, manganese and sulfur smell, and the Whole-Home UV Purifier ($599) adds chemical-free disinfection, since wells have none in the line. All prices are system only.
Cities and communities we serve in Cobb County
Forge Water Co is based in Powder Springs, so Cobb County is home. We work with homeowners across the county, from the Lake Allatoona side of Acworth down to Austell and Mableton.
- Marietta
- Kennesaw
- Acworth
- Smyrna
- Powder Springs
- Austell
- Mableton
How buying works
- 01
10-minute call
Tell us about your home and water. We'll recommend one system, or tell you if you don't need one.
- 02
Unit quote
You get a published unit price for the equipment. No add-ons at the door.
- 03
Your installer
A licensed professional you choose installs it, quotes and bills you directly, and warrants the labor.
Cobb County water FAQ
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