Two different jobs
A water softener treats the whole-house water supply, removing calcium and magnesium (hardness) via ion exchange. It runs all your taps, showers, and appliances on soft water.
A reverse osmosis (RO) system treats drinking water at a single tap (usually the kitchen sink). It uses a membrane to remove dissolved solids, including the sodium added by the softener. Result: bottled-water quality from your faucet.
Side-by-side
Where it sits
- Softener: whole-house, before the water heater.
- RO: point-of-use, under the kitchen sink (or in the basement with a polished water line up to a dedicated drinking-water faucet).
What it removes
- Softener: calcium, magnesium (the two minerals that cause hardness). Slight iron-removal capability (better with iron filter upstream). Does not remove dissolved solids, chemicals, or bacteria.
- RO: dissolved solids (down to 95-99% reduction), sodium, chloride, fluoride, lead, arsenic, nitrate, chromium. Some membranes are certified for [verify: PFAS removal; check NSF/ANSI Standard 58 cert per specific membrane].
What it costs
- Softener: [verify: $1,500-$3,500 installed for a quality home unit; $4,500-$7,000 for a twin-tank or specialty system].
- RO: [verify: $400-$1,200 installed for an under-sink 4- or 5-stage unit; higher for whole-house RO which is unusual in residential].
Operating cost
- Softener: $90-$140/year in salt; annual visit if on a maintenance plan.
- RO: [verify: $80-$200/year in filter replacements (pre-filters every 6-12 months; membrane every 2-5 years)].
Water waste
Conventional RO produces 3-5 gallons of reject ("brine") water per gallon of permeate. Modern units have improved that ratio; some pressurized-tank units claim 1:1 [verify: claims vary by manufacturer; we install the higher-efficiency models when feasible].
Common Wisconsin well-home configurations
"I just want softer water"
Softener alone. Most Walworth County well homes. You may notice the sodium flavor and want to add an RO for drinking water later — we install softeners in a way that allows clean retrofit of an RO.
"My water tastes funny / I don't like buying bottled"
RO alone is rare; usually pair with a softener. RO membranes foul faster on hard water, so the softener protects the RO membrane life.
"I have well water with iron, hardness, and I want clean drinking water"
The full stack: iron filter → softener → RO at the kitchen sink. This is the most common high-performance configuration in our service area.
"There's a known contaminant in my well (PFAS, arsenic, nitrate)"
RO is the right tool for these contaminants at the drinking-water tap. If the contaminant is also a bathing risk, we discuss whole-house options (which can be expensive and require careful selection). [verify: WDNR has a PFAS guidance page; always test for specific concerns].
Failure modes
- RO membrane fouls early if installed without a softener upstream on hard water. Replace the membrane more often, or add the softener.
- Slow tap flow at the RO faucet. Almost always pre-filter clogging or low storage-tank pressure. Annual filter replacement prevents both.
- "Salty taste" from softened water concerning anyone on a low-sodium diet. Calculation: a softener adds approximately [verify: 8 mg of sodium per gallon for each grain of hardness removed]. The fix is potassium chloride instead of sodium chloride in the brine tank, or adding an RO for drinking.
Action
- Schedule a free water test. Well measure hardness, iron, manganese, pH, and TDS, and recommend the right configuration.
- Iron filter vs UV vs softener for the more advanced well-water decisions.
