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How to fix a water softener leak

We'll locate the leak, tighten fittings or replace O-rings, and tell you when to call a plumber.

How-to · Home plumbing
15–30 min
What you'll need
  • Replacement O-rings (exact match for your softener model)
  • Silicone grease (plumber's grease) (optional)
  • Two adjustable wrenches

At a glance

  • Shut off the water supply and bypass the softener before working on it.
  • Locate the leak—valve head, brine tank, drain line, or inlet/outlet fittings.
  • Tighten loose fittings a quarter turn; replace worn O-rings in the valve with exact matches.
  • Check the brine tank for cracks or overflow; replace the float assembly if it sticks.
  • If the valve head is cracked or fittings will not seal, call a plumber.
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Get started

Choose the option that matches what you see. You can jump straight to that section.

Steps

Goal: Shut off water, locate the leak, fix fittings or O-rings, and know when to call a plumber.

  • Shut off the water supply and turn the bypass valve so water flows around the softener. Open a downstream faucet to relieve pressure.
  • Good: No water flows through the softener. Proceed to Locate the leak.
  • Bad: Water still flows—find the correct shutoff or bypass position.

Locate the leak

Goal: Identify where the water is escaping.

  • Dry the valve head, brine tank, drain line, and inlet/outlet fittings. Turn the bypass off briefly so water flows through the softener. Watch where water appears.
  • Good: You see the leak source. Proceed to Tighten fittings or Replace O-rings based on location.
  • Bad: Cannot locate—call a plumber.

Tighten fittings

Goal: Stop leaks at inlet, outlet, or drain line connections.

  • Shut off the water. Use two wrenches to tighten inlet, outlet, or drain line fittings a quarter turn. Do not overtighten. Check that the drain hose is fully inserted and the clamp is snug. Turn the water on and run a regeneration cycle.
  • Good: No drips at the connections. Proceed to Verification.
  • Bad: Still leaks—check O-rings or call a plumber.

Replace O-rings

Goal: Fix leaks at the valve head by replacing worn O-rings.

  • Follow your model’s manual to remove the valve head. Inspect the O-rings for cracks or flat spots. Replace with exact matches from the manufacturer or hardware store. Lubricate with silicone grease and reassemble.
  • Good: No drips at the valve head when the water is on. Proceed to Verification.
  • Bad: Valve head is cracked—call a plumber.

When to get help

Call a plumber if:

  • The valve head is cracked.
  • Fittings will not seal after tightening.
  • Water is spraying under pressure.
  • You are not comfortable working with the softener.

Do not force fittings—you can damage pipes. For other plumbing fixes, see Fix a water filter that leaks or How to unclog a drain.

Verification

  • No drips at the valve head, brine tank, drain line, or fittings when the softener runs.
  • The brine tank does not overflow during regeneration.
  • Water flows normally through the softener with the bypass off.

Reviewed by Blackbox Atlas

Frequently asked questions

Why does my water softener leak?
Common causes: loose inlet/outlet fittings, worn O-rings in the control valve, a cracked brine tank, a stuck float in the brine tank, or a loose drain line connection. Salt and water can corrode seals over time.
Can I fix a water softener leak myself?
Yes, for leaks at fittings, O-rings, or the brine tank float. Shut off the water and bypass the softener first. If the valve head is cracked or you see water spraying, call a plumber.
When should I call a plumber for a water softener leak?
Call a plumber if the valve head is cracked, fittings will not seal after tightening, you have complex plumbing, or water is spraying under pressure. Do not force fittings—you can damage pipes.

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