Yes, softened water is safe to drink. That’s the short answer, and for most people it’s the complete answer.
The longer version is worth knowing because the concern isn’t irrational. Ion exchange softeners do add sodium to water. Whether that matters depends on how much hardness you started with and whether you have specific health reasons to watch sodium.
Where the Concern Comes From
When a water softener works, it replaces calcium and magnesium with sodium. The calcium and magnesium stay trapped on the resin. The sodium goes into the water you drink. That’s the mechanism, and it’s accurate.
For people managing heart disease, hypertension, or kidney disease, sodium in drinking water sounds like a problem. The question is whether the amount is actually significant.
The Actual Numbers
Sodium added by softening scales with source water hardness. The harder your source water, the more sodium the exchange adds.
At 10 gpg source hardness, a liter of softened water contains approximately 200 mg of sodium. At 15 gpg, around 300 mg/L. At 20 gpg, approximately 400 mg/L.
For comparison: a slice of white bread contains about 150 mg of sodium. A tablespoon of soy sauce has around 1,000 mg. A can of chicken noodle soup typically has 800+ mg. A person drinking 2 liters of softened water per day from a 15 gpg source is adding roughly 600 mg of sodium, which is about 26% of the FDA’s 2,300 mg daily reference value.
That’s not zero. But it’s also not the primary driver of sodium intake for most people eating a typical diet.
The WHO Guideline
The World Health Organization’s advisory level for sodium in drinking water is 200 mg/L. This threshold is based on taste detection, not health effects. Softened water from very hard source water (above 12 gpg) can exceed this. Exceeding the taste threshold doesn’t make water unsafe. It means some people might notice a slight salty character at high hardness levels.
Who Should Pay Closer Attention
If your doctor has put you on a strict low-sodium diet, meaning below 1,500 mg/day for a specific medical reason, mention your water softener. The sodium contribution from softened water at high hardness is real and worth including in that conversation.
Infants on formula are another group worth mentioning. Formula prepared with softened water adds sodium from the water itself. This isn’t a danger at typical hardness levels, but parents should be aware of it and mention it to their pediatrician if they have concerns.
The Potassium Chloride Option
This solves the sodium question completely.
Potassium chloride (KCl) is a direct substitution for sodium chloride (NaCl) in the brine tank. The softener works identically. Instead of adding sodium to the water, it adds potassium. Potassium is an electrolyte that most people’s diets are slightly low in, and it doesn’t carry the same restrictions as sodium for most cardiovascular conditions.
Potassium chloride costs 2-3x more per bag than sodium chloride. For most households, the cost difference is $30-60 per year, not a dramatic expense. If sodium is a health concern, the switch is worth it.
The Bypass Drinking Tap
Many water softener installations include a separate faucet at the kitchen sink that pulls from the unsoftened line, bypassing the softener entirely. You get softened water to the dishwasher, washing machine, showers, and all hot water fixtures, and you drink hard water directly from the bypass tap.
This approach makes the sodium question irrelevant and is common in households with people on sodium-restricted diets who still want the appliance and scale benefits of whole-house softening.
The Calcium and Magnesium Question
Some people worry about losing minerals from their water. The idea is that calcium and magnesium in hard water are a meaningful dietary source, and softening removes them.
They aren’t a meaningful dietary source. Milk has 300 mg of calcium per cup. Hard water at 15 gpg contains approximately 170 mg of calcium per liter. You’d need to drink over 3 liters of very hard water to get the calcium equivalent of a single glass of milk. Dietary calcium and magnesium from food dominates completely. Don’t choose hard water for mineral intake.
The Bottom Line
Healthy adults don’t need to worry about softened water. If you’re managing a specific condition with a sodium restriction, switch to potassium chloride regenerant or add a bypass tap. Ask your care team if you’re uncertain about your specific situation.
For a full explanation of how softening works and why sodium gets added in the first place, see how a water softener works. If you’re comparing softeners or deciding between a salt-based and salt-free system, water softeners vs. salt-free conditioners explains the key differences. And for product comparisons, see water softener options.