Almost every water softener is the same handful of parts arranged the same way, which is good news when something stops working. The control valve does the thinking and contains most of the wearing components, the resin does the softening, and the brine tank makes the salt solution that recharges it. Match the symptom to the part and most repairs are straightforward.
The control valve and its wear parts
The valve directs water through service, backwash, brine draw, rinse and refill, and nearly everything that wears in a softener lives inside it. In a piston valve the piston moves through a stack of seals and spacers, and when those seals harden the valve leaks internally, which usually shows as water running continuously to drain or as a softener that never draws brine. The injector, a small venturi, creates the suction that pulls brine from the tank, and it is the single most common blockage point because it has the narrowest passage in the system. Its screen clogs with sediment or salt fines and cleaning it solves a great many no-brine-draw complaints.
Resin, the distributor tube and the media bed
The resin beads do the ion exchange and last many years on clean water, but they are damaged by chlorine over time and fouled by iron, particularly oxidized iron that coats them beyond what regeneration can strip. Resin loss reads as water that is never fully soft despite correct settings and normal salt use. The distributor tube runs down the center of the tank with a screened basket at the bottom to collect treated water without carrying resin into the valve; a cracked tube or a split basket sends resin into the plumbing and into the drain line, which is the diagnosis when you find beads in an aerator.
Brine tank components
Inside the brine tank sit the brine valve assembly, the safety float and, in many units, a grid plate that keeps salt off the floor of the tank so brine can form freely underneath it. The safety float shuts off the refill if the level rises too far, and a stuck float is why a brine tank overflows. The brine valve seals during service and opens for draw and refill; a failed seal lets water into the tank continuously and produces a tank that is always full of water and never draws down. Salt bridging is not a part failure at all, but a crust of salt spanning the tank with a void beneath, and it produces the same symptom as a brine draw fault.
Bypass, o-rings and identifying what you need
The bypass valve lets you isolate the softener from the house, and its o-rings dry out and weep if it has not been moved in years, so exercise it occasionally. O-rings throughout the unit are cheap and are worth replacing as a set when the valve is opened for any reason. Before ordering anything, find the model and serial plate on the valve body or the tank, because parts are model-specific and a valve that looks generic rarely is. Photograph the plate and keep the image somewhere findable. Our guide to sourcing water softener parts near you covers where the common valve families are stocked.
Questions people ask about water softener parts
Why is my softener not using salt?
Most often a blocked injector, a failed brine valve or salt bridging in the tank. All three stop brine reaching the resin, so the unit regenerates without actually recharging.
I found small beads in my faucet aerators. What broke?
That is resin escaping through a cracked distributor tube or a split bottom basket. The tank has to be opened to replace it, and the loose resin flushed from the plumbing.
How long does softener resin last?
Many years on clean water, though chlorine degrades it gradually and iron fouls it. Water that is never fully soft despite correct settings and normal salt use points at the resin.
How do I find the right replacement part?
Work from the model and serial plate on the valve body or tank. Parts are specific to the valve family, and valves that look identical often take different seals and injectors.