Water softener vs. UV water purifier: running cost
A water softener is cheaper to run: about $6 a year versus $63 for an UV water purifier at typical use and 17.99¢/kWh, a $57 difference.
| Water softener | UV water purifier | |
|---|---|---|
| Typical watts | 4 W | 40 W |
| Watt range | 0–15 W | 15–100 W |
| Typical use | 24 hours a day | 24 hours a day |
| Energy per year | 35 kWh | 351 kWh |
| Cost per hour | 0.07¢ | 0.7¢ |
| Cost per day | 1.7¢ | 17¢ |
| Cost per month | $0.53 | $5.26 |
| Cost per year | $6 | $63 |
| Per year in Hawaii (43.51¢) | $15 | $153 |
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What drives the difference
- Water softener: Electric water softeners use a control valve that draws about 3-6 W continuously plus a little during regeneration, roughly 30-50 kWh a year. Non-electric models like Kinetico use none.
- UV water purifier: Whole-house UV systems for well water run their lamp 24/7 at about 25-60 W, so they use 220-500 kWh a year.
Ways to cut either cost
Regenerates based on actual water use, cutting salt and water waste.
See options on AmazonA unit matched to your flow rate avoids overpaying for a larger lamp.
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Frequently asked questions
Which costs more to run, a water softener or an UV water purifier?
At typical use and the U.S. average rate (17.99¢/kWh), an UV water purifier costs about $63 a year versus $6 for a water softener. That's $57 more, or 10.0× as much.
How many watts do water softener and UV water purifier use?
A water softener typically draws 4 W (range 0–15 W). An UV water purifier draws 40 W (range 15–100 W). Watts alone don't decide cost. Hours of use, cycling and standby matter just as much.
Rates: EIA, 12 months ending 2026-07. Methodology.