An old water softener rarely dies outright. It drifts: soap lathers less, the kettle scales again, salt use climbs, and nobody can say when it started. Deciding whether to repair or replace comes down to which part has actually failed, because the tank and the resin have very different lifespans from the control valve on top.
Confirm it has actually stopped softening
Before assuming anything, test. Draw a sample from a tap downstream of the softener and check hardness with a titration kit, then compare against a sample taken before the unit or from an outside tap on the untreated line. If the treated water is hard, the softener is not doing its job; if it is soft, your complaint is something else, such as a plumbing crossover feeding hard water past the unit. A crossover is a surprisingly common cause of mysterious hard water in an otherwise healthy system.
The cheap faults worth checking first
A salt bridge, where a solid crust spans the brine tank above an empty cavity, means the softener draws no brine while the tank looks full. Break it with a broom handle and see whether normal service returns. A blocked injector, a kinked drain line, a stuck brine float or an incorrectly programmed hardness setting all produce the same symptom and cost little to fix. Power interruptions can reset an older controller to defaults. Work through these before considering the resin or the valve, because they account for a large share of apparent failures.
When the resin is the problem
Resin beads have a long life on clean municipal water and a much shorter one where chlorine, iron or manganese are present. Chlorine slowly breaks down the bead structure, and oxidized iron coats it so it can no longer exchange. The signs are gradual: capacity falls, regeneration comes more often, salt use rises, and eventually fine brown particles appear at aerators as the bed breaks down. Replacing the resin in a sound tank is far cheaper than a new system, and it is worth pricing before accepting a replacement quote.
What a newer control valve actually changes
The largest practical difference between an old softener and a current one is the valve. Older timer based controls regenerate on a fixed schedule whether or not the capacity has been used, which wastes both salt and water and still delivers hard water during heavy use. Metered valves regenerate on gallons treated. Newer valves also offer proportional brining, using only the salt the exhausted portion of the bed needs. If your unit still runs on a timer, that alone is a real argument for replacement rather than repair.
Deciding, and dealing with the old unit
Repair when the tank is sound, the resin has life left and the fault is a serviceable part. Replace when the valve body is worn, parts are no longer available, the resin is fouled and the vessel is old, or when several faults appear together. Replacement also lets you resize, since households change. When removing the old unit, drain both tanks, check whether your area treats resin or brine tanks as regular waste, and keep the bypass fitting if it matches. Our water softener installation guide covers sizing the replacement properly.
Questions people ask about old water softener
How long should a water softener last?
The tank and resin outlast the control valve in most cases, and life depends heavily on whether chlorine, iron or manganese have been attacking the resin bed.
Is replacing softener resin worth doing?
Often yes, since new resin in a sound tank costs far less than a whole system and restores capacity when the valve is still working properly.
Why is my old softener suddenly using more salt?
Rising salt use usually means regeneration is happening more often because capacity has fallen, or that brine is being drawn and wasted without restoring the bed.
Should I replace a timer softener with a metered one?
Metered control regenerates on water actually used rather than on a schedule, which cuts salt and water use and avoids hard water during heavy demand.