If water remains hard despite a softener, the cause may be bypass, missing brine, incorrect settings, insufficient regeneration, hardness leakage at high flow, or exhausted resin. Measuring hardness before and after the unit is more useful than judging only by soap lather or spots.
First confirm that the treated water is actually hard
Use an appropriate hardness test on water before and after the unit. If readings are similar, the softener is not reducing hardness; if outlet hardness is low, spotting may come from other minerals or residue.
Check bypass, salt, and regeneration
Check bypass valves, salt level and condition, and whether the control schedules cycles for actual water use and hardness. A setting that is too low can delay regeneration; one that is too high wastes salt without fixing a mechanical fault.
See whether hardness changes at different flow rates
An undersized unit, degraded resin, or internal problem may soften one faucet but leak hardness at high household flow. Compare similar conditions and do not judge from one sample taken during regeneration.
Resin or internal valve problems need specific service
If brine use and programming are normal but hardness remains high, exhausted resin, internal channeling, or a control-valve fault may be involved. Do not open a pressurized control head without the proper procedure and tools.
Sources
- U.S. Environmental Protection Agency WaterSense — Cation Exchange Water Softeners — How cation-exchange water softeners work, regenerate, use salt and water, and can be maintained efficiently.