An installed water softener that came with the house is a question mark: you did not choose it, and you cannot assume it works. The good news is that identifying the unit, checking whether it actually softens, and deciding to service or replace it are all jobs a homeowner can do in an afternoon. This page runs through them in order.
Figure out what you have
Start at the control valve on top of the resin tank: the brand and model are usually on a plate or sticker there, and the model number unlocks the manual, the capacity rating and the parts diagram online. Note the layout: one enclosed cabinet or separate resin and brine tanks, where the bypass valve is, and where the drain line runs. Open the brine tank lid and look: clean salt with visible water movement during regeneration is healthy; a solid crust, a salt bridge, or a mush of sludge at the bottom means the unit has been neglected. Check whether the valve display shows the right time of day, since a wrong clock means past power cuts have shifted regenerations, and photograph everything before touching anything.
Is it actually softening? Simple checks
The definitive check is a hardness test on a tap inside the house, using cheap test strips or a drop kit. The USGS classes water by dissolved calcium and magnesium, from soft at 0 to 60 mg/L as calcium carbonate up through very hard, and a working softener should deliver water at the soft end of that scale regardless of what the raw supply measures. Test an outside spigot too if you have one, since it usually bypasses the softener and shows you the untreated baseline. Softer everyday evidence agrees with the strips: soap should lather readily and shower glass should stay clear between cleans. If the treated tap tests as hard as the spigot, the softener is passing water through without doing its job, whatever its lights say.
Service it or replace it
If the unit is failing, age and the failure mode decide the path. A salt bridge, a clogged brine line, a stuck float or wrong valve settings are cheap fixes any homeowner or service tech can handle. Worn valve seals and pistons are rebuildable on most mainstream brands. What tips the decision toward replacement is exhausted resin in an old unit, an obsolete brand with no parts supply, or an undersized unit that was never right for the house. Compare the repair quote against current replacement pricing on vendor ranges such as SpringWell's softener line, and factor efficiency: modern demand-regeneration valves use less salt and water than old timer units. Our water softener installed cost guide covers what full replacement typically involves.
Questions people ask about installed water softener
How can I tell if the softener in my new house works?
Test an indoor tap with hardness strips and compare against an outside spigot that bypasses the unit. Soft inside and hard outside means it works; equal readings mean it does not.
The previous owner left the softener full of crusted salt. Is it ruined?
Usually not. Break up the salt bridge, clean out the brine tank, refill with fresh salt and run a manual regeneration. If hardness still gets through afterward, have the resin and valve checked.
When is replacing an installed softener smarter than repairing it?
When the resin is exhausted on an old unit, parts are unavailable, or it was undersized from the start. Modern demand-regeneration units also cut salt and water use, which shifts the math.