# What a Water Softener Removes — and What It Does Not > A water softener removes hardness minerals like calcium and magnesium, but not chlorine, bacteria, or dissolved solids. Here is what it does and does not treat. Canonical: https://watertreatmentpro.com/what-does-a-water-softener-remove/ Last updated: 2026-11-09 ## What a Water Softener Removes A water softener removes dissolved calcium and magnesium through ion exchange. As hard water passes through a resin bed, calcium and magnesium ions trade places with sodium or potassium ions held on the resin. The hardness minerals stay on the resin, and softened water flows to the plumbing. During regeneration, a brine solution flushes the accumulated hardness down the drain and recharges the resin with sodium or potassium. This process targets water hardness measured in grains per gallon (GPG). Soft water is 0–3 GPG, moderately hard water is 3–7 GPG, hard water is 7–10 GPG, and very hard water is 10+ GPG. A softener rated at 24,000–64,000 grains can handle different household loads depending on water hardness and daily usage. For example, a household using 300 gallons per day with 10 GPG hardness produces 3,000 grains of hardness per day. A 32,000-grain softener would theoretically need regeneration after roughly 10 days at that load, though actual frequency depends on the valve settings, salt dose, and reserve capacity. ## What a Water Softener Does Not Remove A softener is not a filter for everything in water. It does not meaningfully remove chlorine or chloramine, sediment, bacteria, viruses, dissolved solids such as nitrate, or heavy metals like lead and arsenic. It also does not remove iron reliably above its design limit. Iron is a common exception. Some softeners can handle small amounts of clear-water iron, generally up to about 2–3 ppm, but higher concentrations can foul the resin and reduce capacity. If your water test shows iron above that range, a dedicated iron filter may be more appropriate. Iron filter systems typically run $800–$2,500 installed. Nitrate is another contaminant a softener does not address. The federal drinking water reference limit for nitrate is 10 mg/L. Reducing nitrate usually requires reverse osmosis, distillation, or an anion-specific treatment system, not a standard sodium-based softener. ## Hardness vs. Total Dissolved Solids Homeowners often confuse hardness with total dissolved solids (TDS). A softener removes calcium and magnesium, which contribute to hardness and scale, but it does not lower TDS significantly. In fact, ion exchange replaces hardness minerals with sodium, so TDS may remain about the same or increase slightly. If your goal is to reduce TDS, sodium, nitrate, arsenic, or a broad range of dissolved contaminants, reverse osmosis is the more common point-of-use option. Under-sink RO equipment typically costs $200–$600, with installed costs around $300–$900. Running costs are estimated at $60–$150 per year for filters and membrane replacement. RO membranes usually last 2–3 years, and rejection rates commonly fall in the 80–95 percent range depending on the contaminant and membrane condition. Whole-house RO systems are substantially more expensive, typically $3,000–$8,000 installed. ## Salt, Regeneration, and Ongoing Costs Water softeners use salt to regenerate the resin. A typical regeneration cycle uses an estimated 8–12 pounds of salt, depending on the unit size, programming, and salt setting. Annual salt costs are estimated at $120–$400 for most households, though actual usage varies with water hardness, volume, and local salt prices. Equipment alone generally runs $600–$2,500. Installed, a softener system typically costs $1,200–$4,500, depending on plumbing access, bypass requirements, and whether electrical work is needed. Resin beds typically last 8–12 years before a rebed is needed, which is estimated at $300–$600. The overall softener life is commonly 10–15 years with routine maintenance. If you are comparing purchase options, it helps to look at the full installed price rather than the equipment price alone. More detail on installed pricing is available in our guide to water softener installation cost. ## Alternatives for What Softeners Miss Because a softener only addresses hardness minerals, many homes pair it with other equipment. A whole-house sediment filter protects plumbing and appliances from particles and is often sized for 8–15 GPM flow rates. Carbon filtration addresses chlorine taste and odor and some organic chemicals. Carbon cartridges typically need replacement every 6–12 months at an estimated $80–$300 per year, while sediment cartridges are usually replaced every 3–6 months. For microbiological concerns such as bacteria in private well water, UV treatment is a common option. UV lamps are typically replaced every 12 months at an estimated $30–$90 per lamp. Salt-free conditioners do not remove hardness through ion exchange; they alter how hardness minerals behave, and installed systems typically run $500–$1,800. Sulfur or hydrogen sulfide odors usually require dedicated filtration rather than a softener. Sulfur filter systems are typically $1,000–$3,000 installed. If you are evaluating multiple treatment layers, our whole-house water filter cost guide covers equipment and installation ranges. ## Test Before You Buy Equipment Water treatment decisions should start with a water test, not a product purchase. A laboratory water test typically costs $40–$150 and can measure hardness, iron, pH, nitrate, TDS, and other parameters relevant to sizing and equipment selection. Knowing your actual hardness in GPG and any co-existing contaminants prevents overbuying or choosing the wrong technology. Private well owners are responsible for their own testing schedule, and municipal water customers can request a consumer confidence report from their utility. Once you have results, match the equipment to the specific contaminants found rather than assuming a softener solves every water quality issue. ## Bottom Line A water softener removes calcium and magnesium hardness through ion exchange, and it does so within the limits of its grain capacity and salt programming. It does not remove chlorine, sediment, bacteria, nitrate, or most dissolved solids. If your water contains multiple issues, a combination of softener, filtration, and possibly reverse osmosis may be necessary. Start with a lab test, compare installed costs, and size the system to your measured hardness and household water use. 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