Softener allows hard water through during regeneration, affecting the whole house.

Safety first: Identify which taps are affected and whether any cross‑connections exist (e.g., mixer taps).

• Check bypass manifold: Verify that the Kinetico bypass is in the correct position for normal service and that the installer has not left any isolation valves partially open.
• Test individual lines: If possible, test hardness at different branches to locate where hard water is entering.
• Inspect for cross‑connections: Ensure there is no unsoftened cold feed teeing into softened lines downstream of the softener.
• Internal seal check: If plumbing is correct, internal valve seals may be leaking and allowing hard water bleed‑through; a seal kit replacement is likely required.

Warning: Plumbing alterations should be carried out by a competent plumber familiar with Kinetico systems.