Water softener and whole-house filter guides

A water softener strips calcium and magnesium out of your supply so scale stops forming. A whole-house filter does the other job: chlorine, sediment, taste and odour. Most homes need both, plumbed in that order.

How softeners actually work: ion exchange in plain terms

Inside the tall tank is a bed of plastic resin beads, each carrying a loose sodium ion. Hard water flows through, and because calcium and magnesium hold a stronger charge than sodium they stick to the resin and kick the sodium loose. That trade is the whole trick — ion exchange, nothing more exotic. Eventually every bead is loaded, so the control valve regenerates: it draws strong brine from the salt tank and the concentration of sodium drives the calcium back off to the drain. Hence the salt supply, the drain line and the running cost. Two things follow: softened water carries slightly more sodium, and resin is not immortal, because chlorine oxidises it and iron fouls it.

Sizing by household and grains per gallon

Sizing is arithmetic, not opinion. Take the number of people in the house, multiply by 75 gallons a day — the long-standing residential planning figure — and multiply by your hardness in grains per gallon. That is your daily grain load, and you want a unit rated to cover three to seven days of it so the valve regenerates on a sane schedule instead of every night. Undersize it and you regenerate constantly, burning salt and wearing the valve. Test your water first; a guessed hardness number is worse than useless.

Arithmetic from 75 gallons per person per day, not measured field data. Add roughly 5 grains per gallon of load for every 1 ppm of dissolved iron. Sizing by model is in the softener buying guide.

Saltless water softener: what it does and what it does not

A saltless water softener is a conditioner, and the naming causes most of the disappointment. The common design is template-assisted crystallisation: water passes over a media bed whose surface encourages dissolved hardness to form tiny stable crystals that stay suspended rather than plating onto pipe and heating elements. No salt, no brine, no drain line. What it does not do is remove anything — test the outlet and you get the number you put in, because the minerals are still there in a form less inclined to cement itself to your water heater. Judge it on the right goal: less scale with almost no upkeep, yes; the slick feel of soft water, no.

Salt free water softener versus salt-based: how to actually decide

Four questions settle it. What is your hardness? Below roughly 10 grains per gallon a conditioner has an easy job; past 15 the evidence it fully protects appliances gets thin, and a salt free water softener starts to look like false economy. Is there a drain within reach? No drain means no regeneration. Is anyone watching sodium intake? Potassium chloride solves that at a higher running cost. And what actually annoys you — scale on fixtures, or the feel of the water? The cheaper unit that solves the wrong problem is the expensive one.

Whole house water filter: the other half of the job

A whole house water filter treats what a softener ignores. Sediment cartridges catch sand, silt and rust flakes. Carbon — granular, block, or catalytic where the utility uses chloramine — takes out chlorine taste and musty odours. Neither touches hardness. Sequence matters: sediment first, carbon next so chlorine stops oxidising the resin, softener after that, and UV last, because a lamp only disinfects water that is already clear.

Read from manufacturer specifications and the relevant NSF/ANSI standards — this site does not test hardware. Certifications to look for: NSF/ANSI 44 for cation-exchange softeners, 42 for aesthetic claims, 53 for health claims, 55 for UV, 58 for reverse osmosis.

Water softener maintenance: the short list that matters

Water softener maintenance is mostly one habit: look in the brine tank once a month, checking for two failures. A salt bridge is a hard crust over an empty cavity, so the unit draws brine from a tank that looks full and regenerates with plain water — the classic “it stopped working and I only just filled it” call. Break the crust and stop overfilling; two-thirds is plenty. The second is mushing, where fine salt compacts into sludge and blocks the draw. Cleaner grades make both less likely. Beyond that, run a resin bed cleaner once or twice a year on iron-bearing water. More on water softener salt.

Common questions