Water Hardness Levels for Saltless Systems | 2026

Water hardness measures the concentration of dissolved calcium and magnesium minerals in water. Understanding water hardness measurement is essential for selecting the right saltless water conditioner and predicting system performance. Water hardness is expressed in two common units: grains per gallon (GPG) and parts per million (PPM).

Grains per gallon (GPG) represents the weight of hardness minerals dissolved in one gallon of water. One grain equals 1/7000 of a pound. A water hardness reading of 10 GPG means 10 grains of hardness minerals are dissolved in each gallon of water. Parts per million (PPM) represents the weight of hardness minerals per million units of water weight. The conversion between GPG and PPM is: 1 GPG = 17.1 PPM.

Water hardness testing can be performed through home test kits, professional laboratory analysis, or municipal water quality reports. Most municipalities provide annual water quality reports that include hardness measurements. Professional water testing provides the most accurate results and identifies other water quality parameters beyond hardness, such as iron, manganese, and pH levels.

Saltless water conditioners perform optimally for water hardness between 5–25 grains per gallon (GPG), which corresponds to 85–425 parts per million (PPM). Within this range, saltless conditioners effectively crystallize hardness minerals and prevent scale buildup in pipes and appliances. The TAC media in saltless conditioners is engineered to handle mineral concentrations within this range without fouling or losing effectiveness.

Water hardness below 5 GPG doesn't require treatment, as the mineral concentration is too low to cause significant scale problems. Water hardness above 25 GPG exceeds the optimal range for saltless conditioners and may result in reduced effectiveness or faster media fouling. Very hard water above 25 GPG may require salt-based softening or hybrid systems combining conditioning with additional treatment stages.

For water hardness in the 5–25 GPG range, saltless conditioners provide reliable scale prevention and protect appliances and plumbing from mineral damage. The system's TAC media crystallizes hardness minerals effectively, and the media lifespan remains within expected ranges (6 years or 1 million gallons). Performance expectations are consistent and predictable within this optimal range.

Water hardness below 5 GPG requires no treatment. If your water hardness is below 5 GPG, a saltless conditioner is unnecessary and provides no benefit. Focus on other water quality issues if present, such as sediment, iron, or chlorine taste/odor.

Water hardness between 5–15 GPG represents the ideal range for saltless conditioners. Most municipal water supplies fall within this range. Saltless conditioners deliver excellent scale prevention and mineral crystallization at these hardness levels. The TAC media remains effective throughout its expected lifespan, and maintenance requirements are minimal.

Water hardness between 15–25 GPG is still suitable for saltless conditioners, though effectiveness may be slightly reduced compared to lower hardness levels. The system still prevents scale buildup effectively, but the TAC media may require replacement slightly sooner due to higher mineral load. Systems should be properly sized for peak flow rate to maintain effectiveness at these higher hardness levels.

Water hardness above 25 GPG exceeds the optimal range for saltless conditioners. At these hardness levels, salt-based water softeners or hybrid systems combining conditioning with softening may provide better results. Very hard water (above 25 GPG) can foul TAC media more quickly and may result in reduced scale prevention effectiveness. If your water hardness exceeds 25 GPG, consult with a water treatment professional about appropriate solutions.