A full-looking salt tank does not prove that a water softener is working. Salt can form a hard crust above an empty space, the system can fail to draw brine, or a valve can leave untreated water flowing around the unit. Meanwhile, scale, spotting, and poor soap performance gradually return.
The useful question is not simply whether the softener has salt. It is whether the unit is regenerating with brine and delivering consistently soft water afterward. You can narrow that down without dismantling the control valve or guessing which part needs replacement.
Confirm that hardness is actually returning
Do not diagnose the softener from one cloudy glass or one load of spotted dishes. Dishwasher detergent, rinse aid, water temperature, and residue inside a water heater can produce similar signs.
Test hardness at two clearly identified locations. Take one sample from untreated water, such as a faucet known to be upstream of the softener, and another from a cold faucet downstream. Let each faucet run long enough to clear water that was sitting in the pipe. Use the same hardness test and sampling method for both.
If both samples have similar hardness, the softener is probably being bypassed, has run out of usable capacity, or is not regenerating correctly. If the treated sample is soft, investigate the particular fixture or appliance where the problem appears before blaming the entire system.
Repeat the treated-water test at roughly the same point in the softener's operating cycle. A sample taken immediately after regeneration may look fine even when the system runs out of capacity before the next scheduled cycle.
Check the bypass before changing settings
Find the bypass valve where the plumbing connects to the softener. Confirm that it is fully in the service position. Some installations use a built-in sliding valve. Others use several separate plumbing valves.
A partially open bypass can blend hard water into the treated line. A fully bypassed unit may still display the time and appear normal even though no household water is passing through the resin tank.
Photograph the valve positions before moving anything. If the arrangement is unclear or the valves are stiff, ask the installer or a plumber to identify the normal service position. Forcing an old valve can create a leak that is more urgent than the original softening problem.
Look for a salt bridge without striking the tank
A salt bridge is a hardened layer with an empty space beneath it. From above, the brine tank can look full while the water and salt below are no longer making proper contact.
Shine a light into the tank and compare the apparent salt level with recent salt use. If the level has not moved through several regenerations, a bridge is possible. Gently press different areas of the salt surface with a smooth wooden or plastic handle. A solid shelf with a hollow area beneath it feels different from loose pellets.
Do not hammer the tank or use a sharp metal object. The brine well, float assembly, tubing, and tank wall can be damaged. If a crust is present, break it carefully from the top and remove loose chunks without disturbing the internal parts.
Also look for a thick paste at the bottom rather than a suspended crust. This is sometimes called salt mushing. Adding more salt on top does not correct it. The tank may need to be emptied and cleaned according to the equipment instructions.
Watch what happens during regeneration
The control display can show that a regeneration was scheduled, but that does not prove every stage occurred. Start a manual regeneration only when the drain route is clear and you can remain nearby to watch for leaks or overflow.
Listen for water flowing to the drain during the appropriate stages. Later, inspect the brine tank to see whether its water level changes. The expected level and timing vary by design, so compare what you observe with the manual instead of assuming that a visible pool is always good or always bad.
If the system sends water to the drain but never draws liquid from the brine tank, possible causes include a blocked injector, restricted brine line, air leak, stuck float assembly, or control-valve problem. Those parts often require cleaning, testing, or service rather than a larger salt delivery.
If the brine tank keeps filling toward overflow, place the unit in bypass if necessary to prevent water damage and arrange service. Do not keep initiating regenerations to see whether the problem clears itself.
Check whether the softener knows how much water was used
Metered softeners regenerate based partly on recorded water use. Compare the current flow or usage display, if available, while someone opens and closes a downstream cold faucet. A display that never registers flow may point to a meter, cable, turbine, or programming problem.
Also check the clock after a power interruption and review the programmed hardness, household capacity, regeneration mode, and time of regeneration. Record every value before changing it. An incorrect setting can cause regeneration too late, too rarely, or with an unsuitable salt dose.
Do not raise the hardness or capacity setting simply to make the unit regenerate more often. That can hide the actual problem and increase salt and water use. The settings should correspond to the tested untreated-water hardness, any relevant adjustment specified by the manufacturer, the resin capacity, and the chosen salt dose.
Use one regeneration as a diagnostic checkpoint
After confirming that the bypass is in service, the salt is loose, and the unit can safely drain, complete one manual regeneration. Then run a downstream cold faucet briefly and test the treated water again.
If the water becomes soft but turns hard again well before the next expected regeneration, the unit may have insufficient usable capacity for the household's water demand. Possible explanations include incorrect programming, increased water use, resin fouling, an undersized unit, or hardness entering the home that is higher than the setting assumes.
If the water remains hard immediately after a complete regeneration, focus on brine draw, valve operation, internal distribution, resin condition, or untreated-water blending. Repeated regeneration is unlikely to solve a mechanical fault and can send unnecessary water to the drain.
Know what evidence to give a service provider
Before requesting service, write down the model, valve type, approximate salt level, bypass position, displayed settings, and any error code. Record untreated and treated hardness results, when the last regeneration occurred, whether water flowed to the drain, and whether the brine level changed.
Ask the provider to identify the failed check before recommending replacement. Useful questions include whether the unit draws brine, whether the meter records flow, whether the programmed capacity matches the equipment, whether untreated water is blending through the bypass, and whether the resin can still deliver the expected capacity.
If replacement is proposed, ask for the diagnosis and the proposed equipment in writing. Then compare providers on the same problem and scope of work. The site's methodology explains the factors used to match systems and compare providers, while the system finder and provider comparison can help organize the next step.
Stop troubleshooting when water or electricity is involved
Place the unit in bypass and call for service if the brine tank is close to overflowing, a drain connection is leaking, the control head is spraying water, or electrical components are wet. Bypass protects the house from the immediate equipment problem, but it also means the home will receive untreated water until service is restored.
The earliest useful warning is often a mismatch: the salt appears full, yet hardness at a downstream cold tap is rising. Catch that mismatch with a simple comparison test, then follow the water path through the bypass, brine tank, regeneration cycle, and meter. That sequence gives you a much better basis for deciding whether the softener needs a minor correction, a repair visit, or replacement.