You probably need a water softener if your water is above about 7 gpg (120 mg/L) and scale is costing you time or money; below about 3.5 gpg (60 mg/L) you almost certainly don’t. In between, it’s a judgement call that depends on your appliances, how much the scale bothers you and whether you’re happy to keep buying salt. Hardness isn’t a health issue, so this is a household decision, not a safety one.
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Use the checklist below, then weigh the running costs in the table. If you’re new to the topic, hard water vs soft water and water softeners explained cover the basics. If you don’t know your hardness yet, our guide to what hard water is shows where to find it.
Step 1: find your number
Look up your hardness in your water utility’s annual report, or test a well. Then place it on the scale:
| Your water | USGS class | Case for a softener |
|---|---|---|
| 0–3.5 gpg (0–60 mg/L) | Soft | None. Nothing to remove. |
| 3.5–7 gpg (61–120 mg/L) | Moderately hard | Weak. Descaling and appliance settings usually cope. |
| 7–10.5 gpg (121–180 mg/L) | Hard | Reasonable, especially with the checklist items below. |
| Over 10.5 gpg (180+ mg/L) | Very hard | Strong. Scale builds quickly on anything heated. |
Some examples from utility data: Austin averaged 5.4 gpg in 2025, Las Vegas is 16 gpg and San Antonio 15 to 20 gpg.
Step 2: the checklist
Each “yes” strengthens the case. Two or more on water above 7 gpg, and a softener is likely worth it.
- You have a tankless water heater, boiler or espresso machine. Their narrow heat exchangers scale up fastest. Check the manual: some set a maximum hardness or require more frequent descaling on hard water.
- You use a reverse osmosis system or UV unit. The Vermont Department of Health notes that hardness scales RO membranes and UV bulbs, and that industry guidance suggests keeping hardness at or below about 120 to 170 mg/L (7 to 10 gpg) for membrane systems.
- You’re descaling something every month. Kettle, shower heads, coffee maker, glass doors. If that’s a chore you resent, a softener removes most of it.
- Your water heater rumbles or has been replaced early. The USGS points to scale reducing the efficiency of electric water heaters and shortening equipment life.
- Soap and detergent don’t lather. Hard water reacts with soap to form scum, so you use more of it.
- You’re on a well with high hardness. Well water is often harder than nearby mains supplies, and there’s no utility treating it.
Step 3: the reasons to hold back
- Your utility already softens. The Minnesota Pollution Control Agency points out that some cities soften their water before it reaches you. Austin, for instance, uses lime softening at all three of its treatment plants.
- Sodium. Salt-based softening adds sodium: about 0.46 mg for every mg of hardness removed, according to the Vermont Department of Health, or roughly 7.9 mg/L for each gpg, according to Morton. If you’re on a sodium-restricted diet, ask your doctor; many water companies suggest keeping the kitchen cold tap unsoftened anyway.
- Local rules and the environment. Softener brine adds chloride to wastewater. The MPCA reports that 68 Minnesota lakes and streams exceed its chloride standard, and some areas restrict or discourage salt-based softeners. Check before you buy.
- Ongoing effort. Salt bags, monthly checks and the occasional salt bridge.
Step 4: what it costs to run
For a family of four using 80 gallons each a day, with an efficiency-rated softener (3,350 grains of hardness per lb of salt, the NSF/ANSI 44 minimum) and salt at $8.76 per 40 lb bag:
| Hardness | Salt per year | Salt cost per year | Regeneration water per year |
|---|---|---|---|
| 3 gpg (51 mg/L) | 105 lb | $23 | 1,752 gal |
| 5 gpg (86 mg/L) | 174 lb | $38 | 2,920 gal |
| 7 gpg (120 mg/L) | 244 lb | $53 | 4,088 gal |
| 10 gpg (171 mg/L) | 349 lb | $76 | 5,840 gal |
| 15 gpg (257 mg/L) | 523 lb | $115 | 8,760 gal |
| 20 gpg (342 mg/L) | 697 lb | $153 | 11,680 gal |
The purchase and installation come on top. The running cost scales with hardness, so at 5 gpg you’d spend about $38 a year on salt to avoid fairly mild scale, while at 20 gpg you’d spend $153 to avoid a lot of it. Try your own numbers:
This calculator needs JavaScript. Salt per year (lb) = people × 80 × hardness × 365 ÷ 3,350.
Alternatives to a full softener
Descale on a schedule. For moderately hard water, vinegar or citric acid a few times a year handles kettles, shower heads and taps. See how to remove limescale.
Point-of-use protection. A scale filter on a coffee machine, the dishwasher’s own softener set correctly, a wire scale collector in the kettle.
A salt-free conditioner. Wessex Water describes conditioners as changing the minerals so they’re less likely to form scale when heated, without removing them. The MPCA lists them as a salt-free option that costs more and doesn’t remove minerals. Results vary more than with a softener, so look for independent test data.
Tank exchange. The MPCA also mentions services that swap in a pre-softened tank and recharge the used one off-site, so no brine goes down your drain.
If you decide yes
- Size it to your hardness and household: what size water softener do I need.
- Choose a demand-initiated (metered) model. The MPCA notes these use only the salt needed, unlike timer models.
- Bypass outdoor taps and consider leaving the kitchen cold tap unsoftened.
- Set the hardness correctly: hardness setting guide.
- Check for local rebates; the MPCA mentions city rebates for high-efficiency softeners in Minnesota.
Frequently asked questions
Is a water softener worth it for 10 gpg water?
Often, yes. 10 gpg is “hard” on the USGS scale, and a family of four would spend about $76 a year on salt. If you have a tankless heater, an RO system or a lot of descaling to do, the case is stronger.
Do I need a water softener if I have city water?
It depends on the city. Look up your utility’s hardness figure; some cities soften at the plant and deliver moderately hard water, others deliver very hard water.
Is hard water bad for my health?
No. The USGS calls hardness a nuisance rather than a health concern, and the EPA has no limit for it.
Can a softener damage pipes?
Very soft water can be more corrosive than hard water; the Las Vegas Valley Water District notes that its hard water is less corrosive to pipes. Follow the installer’s guidance on settings, and don’t soften more than you need to.
