Why a Failing Resin Tank Could Be Wrecking Your Water Quality When you need to repair a water softener resin tank, the fix usually comes down to one of two things: the resin bed is exhausted or damaged and needs replacing, or the control valve is the real culprit. Here's how to tell the difference at a glance: Quick answer — how to repair a water softener resin tank: Check salt usage first. If your softener is using salt at its normal rate but still producing hard water, the