How much does it cost to run an UV water purifier?
An UV water purifier costs about 0.7¢ per hour, 17¢ a day, $5.26 a month and $63 a year at typical use (24 hours a day) and the U.S. average rate of 17.99¢/kWh. 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.
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Cost by hours of use
| Hours per day | kWh/day | Per day | Per month | Per year (all year) |
|---|---|---|---|---|
| 1 hour | 0.04 | 0.7¢ | $0.22 | $3 |
| 2 hours | 0.08 | 1.4¢ | $0.44 | $5 |
| 4 hours | 0.16 | 2.9¢ | $0.88 | $11 |
| 8 hours | 0.32 | 5.8¢ | $1.75 | $21 |
| 12 hours | 0.48 | 8.6¢ | $2.63 | $32 |
| 24 hours | 0.96 | 17¢ | $5.26 | $63 |
Cost to run an UV water purifier in every state
The same UV water purifier costs $43 a year in North Dakota and $153 in Hawaii, at each state's average residential rate (12 months ending July 2026).
| State | Rate | Per hour | Per month | Per year |
|---|---|---|---|---|
| North Dakota | 12.32¢ | 0.5¢ | $3.60 | $43 |
| Idaho | 12.65¢ | 0.5¢ | $3.70 | $44 |
| Nebraska | 12.86¢ | 0.5¢ | $3.76 | $45 |
| Louisiana | 12.99¢ | 0.5¢ | $3.80 | $46 |
| Utah | 13.32¢ | 0.5¢ | $3.89 | $47 |
| Nevada | 13.36¢ | 0.5¢ | $3.90 | $47 |
| Arkansas | 13.43¢ | 0.5¢ | $3.92 | $47 |
| Tennessee | 13.56¢ | 0.5¢ | $3.96 | $48 |
| Oklahoma | 13.70¢ | 0.5¢ | $4.00 | $48 |
| Montana | 13.84¢ | 0.6¢ | $4.04 | $49 |
| Kentucky | 13.92¢ | 0.6¢ | $4.07 | $49 |
| Missouri | 13.95¢ | 0.6¢ | $4.08 | $49 |
| Wyoming | 14.01¢ | 0.6¢ | $4.09 | $49 |
| Washington | 14.12¢ | 0.6¢ | $4.13 | $50 |
| Iowa | 14.13¢ | 0.6¢ | $4.13 | $50 |
| South Dakota | 14.20¢ | 0.6¢ | $4.15 | $50 |
| Mississippi | 14.77¢ | 0.6¢ | $4.32 | $52 |
| North Carolina | 14.77¢ | 0.6¢ | $4.32 | $52 |
| Kansas | 15.09¢ | 0.6¢ | $4.41 | $53 |
| Georgia | 15.12¢ | 0.6¢ | $4.42 | $53 |
| New Mexico | 15.32¢ | 0.6¢ | $4.48 | $54 |
| Florida | 15.39¢ | 0.6¢ | $4.50 | $54 |
| Arizona | 15.40¢ | 0.6¢ | $4.50 | $54 |
| West Virginia | 15.48¢ | 0.6¢ | $4.52 | $54 |
| Oregon | 15.50¢ | 0.6¢ | $4.53 | $54 |
| South Carolina | 15.64¢ | 0.6¢ | $4.57 | $55 |
| Texas | 15.96¢ | 0.6¢ | $4.66 | $56 |
| Minnesota | 16.22¢ | 0.6¢ | $4.74 | $57 |
| Alabama | 16.44¢ | 0.7¢ | $4.80 | $58 |
| Virginia | 16.48¢ | 0.7¢ | $4.82 | $58 |
| Colorado | 16.58¢ | 0.7¢ | $4.84 | $58 |
| Indiana | 16.94¢ | 0.7¢ | $4.95 | $59 |
| Delaware | 17.79¢ | 0.7¢ | $5.20 | $62 |
| Ohio | 18.25¢ | 0.7¢ | $5.33 | $64 |
| Wisconsin | 18.74¢ | 0.7¢ | $5.48 | $66 |
| Illinois | 18.79¢ | 0.8¢ | $5.49 | $66 |
| Pennsylvania | 20.70¢ | 0.8¢ | $6.05 | $73 |
| Maryland | 21.03¢ | 0.8¢ | $6.14 | $74 |
| Michigan | 21.05¢ | 0.8¢ | $6.15 | $74 |
| New Jersey | 23.78¢ | 1.0¢ | $6.95 | $83 |
| Vermont | 23.80¢ | 1.0¢ | $6.95 | $83 |
| District of Columbia | 24.20¢ | 1.0¢ | $7.07 | $85 |
| New Hampshire | 26.67¢ | 1.1¢ | $7.79 | $94 |
| Alaska | 26.85¢ | 1.1¢ | $7.85 | $94 |
| Connecticut | 27.99¢ | 1.1¢ | $8.18 | $98 |
| New York | 28.39¢ | 1.1¢ | $8.30 | $100 |
| Rhode Island | 29.27¢ | 1.2¢ | $8.55 | $103 |
| Maine | 29.31¢ | 1.2¢ | $8.56 | $103 |
| Massachusetts | 30.43¢ | 1.2¢ | $8.89 | $107 |
| California | 32.99¢ | 1.3¢ | $9.64 | $116 |
| Hawaii | 43.51¢ | 1.7¢ | $12.71 | $153 |
How to cut the cost
- Don't switch the lamp off between uses; it needs to stay on to stay effective, so size it correctly instead.
- Replace the lamp yearly; aging lamps lose UV output but not power draw.
- Pre-filter sediment so a smaller UV unit is adequate.
Cheaper ways to get the job done
A unit matched to your flow rate avoids overpaying for a larger lamp.
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Compare with similar appliances
| Appliance | Watts | Typical use | Per month | Per year |
|---|---|---|---|---|
| UV water purifier | 40 | 24 hours a day | $5.26 | $63 |
| Water softener | 4 | 24 hours a day | $0.53 | $6 |
| Well pump | 1,400 | 1 hour a day | $7.67 | $92 |
| Septic aerator | 80 | 24 hours a day | $10.51 | $126 |
| Home security system | 8 | 24 hours a day | $1.05 | $13 |
| Electric gate opener | 250 | 3 minutes a day | $0.72 | $9 |
| Security camera | 5 | 24 hours a day | $0.66 | $8 |
Head-to-head comparisons
Frequently asked questions
How much does it cost to run an UV water purifier per hour?
An UV water purifier drawing 40 watts uses 0.04 kWh per hour. At the U.S. average of 17.99¢/kWh that's 0.7¢ per hour. In North Dakota (12.32¢) it's 0.5¢. In Hawaii (43.51¢) it's 1.7¢.
How much does it cost to run an UV water purifier per month?
At typical use (24 hours a day), an UV water purifier costs about $5.26 a month and $63 a year, at the U.S. average rate. Enter your ZIP in the calculator above for your utility's rate.
How many watts does an UV water purifier use?
Most UV water purifiers use 15 to 100 watts. Check the label on the back or bottom for your model's exact rating.
How many kWh does an UV water purifier use?
About 0.96 kWh a day and 351 kWh a year at typical use (24 hours a day).
Does an UV water purifier use a lot of electricity?
It's a moderate load: 351 kWh a year is about 3% of the average U.S. home's yearly use.
Is it cheaper to run an UV water purifier or a water softener?
At typical use, an UV water purifier costs about $63 a year versus $6 for a water softener. So the water softener is cheaper by about $57 a year. Use the comparison table above to compare them at your own settings.
How can I lower the cost of running an UV water purifier?
- Don't switch the lamp off between uses; it needs to stay on to stay effective, so size it correctly instead.
- Replace the lamp yearly; aging lamps lose UV output but not power draw.
- Pre-filter sediment so a smaller UV unit is adequate.
Rates updated 2026-10-21: EIA data through July 2026. Typical wattage and usage reviewed against DOE, ENERGY STAR and manufacturer specs. Methodology.