Is Softened Water Safe to Drink? (Sodium Math + Who Should Avoid It)
Quick answer: yes, for most people. A salt-based softener adds a little sodium: about 8 mg per liter for every grain per gallon (gpg) of hardness it removes, according to North Dakota State University Extension. With 15 gpg water, that’s about 28 mg in an 8-ounce glass, or about 1% of the 2,300 mg daily limit. People on very low-sodium diets should talk to their doctor, and Health Canada advises people with kidney disease and some other conditions to avoid softened water made with potassium chloride. The easy fixes are a hard water tap for drinking or a reverse osmosis filter at the kitchen sink. NHS guidance also says not to use artificially softened water to make baby formula.
Health note: this page summarizes public health guidance; it isn’t medical advice. If you’re on a sodium- or potassium-restricted diet, have kidney or heart disease, or are preparing infant formula, ask your doctor about your drinking water.
How much sodium does a water softener add?
A softener swaps the calcium and magnesium in your water for sodium. NDSU Extension puts the amount at about 8 mg of sodium per liter for every grain per gallon of hardness removed. So the harder your water, the more sodium ends up in it:
| Hardness | Sodium added | Per 8-oz glass |
|---|---|---|
| 5 gpg | 40 mg/L | About 9 mg |
| 10 gpg | 80 mg/L | About 19 mg |
| 15 gpg | 120 mg/L | About 28 mg |
| 20 gpg | 160 mg/L | About 38 mg |
| 30 gpg | 240 mg/L | About 57 mg |
gpg × 8 = mg/L of sodium added (NDSU). An 8-ounce glass is about 0.237 liters. Add any sodium already in your water, which your utility’s water quality report may list.
For comparison, the FDA’s Daily Value for sodium is 2,300 mg, and it defines “very low sodium” food as 35 mg or less per serving. At 15 gpg, eight glasses a day add about 230 mg of sodium, about a tenth of the daily limit. You may see a figure of “12.5 mg per glass” attributed to Mayo Clinic; that page is no longer on Mayo’s site, but the number matches NDSU’s math for water of about 7 gpg.
Softened water sodium calculator
Enter your untreated water’s hardness to see how much sodium (or potassium) your softener adds to what you drink.
Enter your hardness to see the sodium.
How it works: sodium added = gpg × 8 mg/L (NDSU Extension). Potassium is calculated the same way, at about 13.4 mg/L per gpg, because the softener swaps the same amount of hardness for heavier potassium. A glass is 8 ounces (0.237 L). Limits shown are the FDA’s 2,300 mg Daily Value and EPA’s guidance levels for drinking water.
Who should avoid drinking softened water?
- People on very low-sodium diets. For people restricted to 500 mg of sodium a day, EPA recommends drinking water with no more than 20 mg/L of sodium. Softened water from just 3 gpg hardness passes that. EPA says this level is for people on that diet and shouldn’t be applied to everyone, and it advises them to talk to their health care provider about another water source or point-of-use treatment.
- People with kidney disease or other conditions, if you use potassium chloride. Health Canada says potassium from softeners is unlikely to harm healthy people, but could have significant health effects in people with kidney disease, heart disease, coronary artery disease, high blood pressure or diabetes, and in people taking medications that affect potassium. It recommends they avoid drinking softened water.
- Babies’ formula. NHS guidance says not to use artificially softened water to make up infant formula. Use your unsoftened cold tap, and follow your pediatrician’s advice.
For everyone else, softened water is fine to drink. It may taste a little different: EPA notes that taste-sensitive people can notice sodium at 30 to 60 mg/L, which softened water from about 4 to 8 gpg reaches. If yours tastes clearly salty, something may be wrong; see why softened water tastes salty.
Sodium vs potassium chloride
| Sodium chloride (salt) | Potassium chloride | |
|---|---|---|
| Adds to water | Sodium, about 8 mg/L per gpg | Potassium instead of sodium |
| Cost and use | Cheaper | Costs more, and about 10% more is used (NDSU) |
| Best for | Most homes | Cutting sodium, if no one at home has a condition that requires limiting potassium |
| Avoid if | Very low-sodium diet, unless you keep a separate drinking tap | Kidney disease or the other conditions Health Canada lists |
From NDSU Extension and Health Canada. Check that your softener’s manual allows potassium chloride; Whirlpool’s, for example, has a salt-type setting for it.
How to get unsoftened or low-sodium drinking water
- Keep a hard water tap for drinking. Run a separate unsoftened cold line to the kitchen sink. NDSU suggests leaving one kitchen tap unsoftened, and Health Canada recommends having some water bypass the softener. Idaho’s plumbing code even requires a cold hard-water line at the kitchen sink in new homes with a softener loop; see how to install a softener.
- Add reverse osmosis at the kitchen sink. RO removes the sodium a softener adds, along with other dissolved solids. A softener ahead of it also protects the RO membrane. See softener vs RO.
- Switch to potassium chloride, if no one in your home needs to limit potassium.
- Consider a salt-free system if what you mainly want is scale control; it adds no sodium but doesn’t soften. See salt vs salt-free.
Reverse osmosis systems for softened water
Waterdrop G3P600
A tankless under-sink RO system that makes up to 600 gallons a day, so there’s no storage tank taking up cabinet space.
- Certification: certified by IAPMO R&T to NSF/ANSI 58 and NSF/ANSI 372 (lead-free)
- Efficiency: 2:1 pure-to-drain ratio
- Needs: an electrical outlet under the sink
Good to know: check its Performance Data Sheet for the specific contaminants it’s certified to reduce. Full details in our softener vs RO guide.
Check price on AmazoniSpring RCC7AK
A traditional six-stage RO system with a storage tank and a remineralization stage that adds some minerals back after filtering.
- Capacity: up to 75 gallons a day, with a storage tank
- Certified reductions: iSpring lists TDS, fluoride and lead among others
Good to know: the tank takes more cabinet space than a tankless system, and we didn’t find an official drain ratio.
Check price on AmazonIs softened water OK for plants?
Avoid using softened water on plants. NMSU Extension notes that sodium is toxic to plants at fairly low concentrations and builds up in the soil over time, and Colorado State University’s PlantTalk lists softened water as a source of salt buildup in houseplants. Use an unsoftened tap instead; Whirlpool also recommends leaving outside faucets on hard water. If salts have already built up in a pot, flush the potting mix with plenty of water.
Frequently asked questions
Can you drink water from a water softener?
Yes. Softened water is the same tap water with its hardness swapped for sodium or potassium. Most people can drink it; the exceptions are the groups above.
Are water softeners bad for your health?
Not for most people. The concerns are the added sodium for people on very low-sodium diets and added potassium for people with kidney disease or similar conditions. For the benefits and downsides, see water softener benefits.
Does softened water raise blood pressure?
The sodium it adds is small compared with food: about 28 mg per glass at 15 gpg, against a 2,300 mg daily limit. If you have high blood pressure and are told to limit sodium, talk to your doctor, and consider a hard water tap or RO for drinking. If you use potassium chloride, Health Canada lists high blood pressure among the conditions where extra potassium could be a concern.
Can I cook with softened water?
The same sodium math applies. For most people it’s fine; if you’re limiting sodium, cook with water from your hard water tap or RO faucet.
Is softened water safe for babies?
NHS guidance says not to use artificially softened water to make up infant formula. Use the unsoftened cold tap, and ask your pediatrician what they recommend.
Related guides
- Water softener vs reverse osmosis
- Salt vs salt-free water softeners
- Water softener benefits: is it worth it?
- Best water softeners
Sources
- NDSU Extension, Water Softening (Ion Exchange), WQ1031 (revised May 2022): sodium added, potassium chloride, a hard water tap.
- U.S. Environmental Protection Agency, Drinking Water Advisory: Consumer Acceptability Advice and Health Effects Analysis on Sodium, EPA 822-R-03-006 (February 2003).
- U.S. Food and Drug Administration, Sodium in Your Diet.
- Health Canada, Guidance on Potassium from Water Softeners.
- NHS, How to make up a feed.
- NMSU Extension, Southwest Yard & Garden (May 1999), and Colorado State University Extension, Leaching Salts from Potting Mixes.
- Idaho plumbing code amendments via Cornell Law School’s Legal Information Institute; Whirlpool WHES48 manual.
- Waterdrop and iSpring product pages, via our softener vs RO guide.