The short answer
Check the bypass, salt, hardness setting and regeneration first; then the valve seals and piston; worn or fouled resin comes last.
Quick checks
- The bypass is in service, not bypass.
- There's salt and no bridge.
- The hardness setting matches your water (plus iron).
- The clock time is right so it regenerates overnight.
Valve problems
Worn seals and spacers or a scored piston can let hard water bypass the resin. Rebuild kits: onerbl 560006-019 for Fleck 5600SE Power Supply, Better Home Water Treatment WS1 for Clack WS1 Valve Rebuild Kit.
Resin
If everything else checks out, the resin may be worn or iron-fouled; re-bed to the same volume (resin calculator) with AFWFilters SOFRES1 1 cu ft Softener Resin.
Products mentioned
Valve part · onerbl
onerbl 560006-019 for Fleck 5600SE Power Supply
Valve part · Fleck 5600SE
Valve part · Better Home Water Treatment
Better Home Water Treatment WS1 for Clack WS1 Valve Rebuild Kit
Valve part · clack ws1
Standard cation resin · AFWFilters
AFWFilters SOFRES1 1 cu ft Softener Resin
Standard cation resin · 1 cu ft
Questions readers ask
Why is my water still hard after the softener?
Most often bypass left open, no salt, a salt bridge or a hardness setting below your water.
How do I test if my softener is working?
Test a softened tap and an unsoftened tap with strips; softened water should read near zero.