Garden 
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An unheated in-ground pool typically runs $60 to $200 a month in season, and the pump is usually more than half of it. Rather than trust an average, work out your own: pump wattage divided by 1,000, times hours per day, times 30, times your electricity rate. Add roughly $25 to $60 a month for chemicals, $8 to $15 for evaporated water, and — if you heat — a heating bill that can exceed everything else put together. Every figure below is worked at a representative US residential rate of $0.17 per kWh, which is a stated example, not a claimed national average. Substitute the rate printed on your own bill; it may be anywhere from about $0.11 to over $0.30 depending on your state and utility, and the Energy Information Administration publishes the state averages.
The pump: the arithmetic that decides everything
The formula is short:
Monthly cost = (watts ÷ 1,000) × hours per day × 30 × rate per kWh
Worked for a common setup — a 1.5 HP single-speed pump drawing about 1,800 watts, running 8 hours a day, at $0.17 per kWh:
- 1,800 ÷ 1,000 = 1.8 kW
- 1.8 × 8 hours = 14.4 kWh per day
- 14.4 × 30 = 432 kWh per month
- 432 × $0.17 = about $73 per month
Now the same pool with a variable-speed pump running at a low filtration speed, drawing roughly 250 watts, for 12 hours a day:
- 250 ÷ 1,000 = 0.25 kW
- 0.25 × 12 = 3 kWh per day
- 3 × 30 = 90 kWh per month
- 90 × $0.17 = about $15 per month
Same pool, same water turnover, roughly a fifth of the cost. That is not a marketing claim — it falls out of the physics. A pump's power draw rises steeply with speed, roughly with the cube of it, so halving the speed cuts power far more than it cuts flow — ENERGY STAR puts a half-speed pump at one eighth the energy. Running slow for longer is simply a cheaper way to move the same water, which is why federal efficiency standards have made variable-speed the default for most in-ground pool pumps.
| Pump | Draw | Hours/day | kWh/month | At $0.17/kWh | At $0.30/kWh |
|---|---|---|---|---|---|
| 1.5 HP single-speed | 1,800 W | 8 | 432 | $73 | $130 |
| 1.5 HP single-speed | 1,800 W | 12 | 648 | $110 | $194 |
| Variable-speed, low | 250 W | 12 | 90 | $15 | $27 |
| Variable-speed, low | 350 W | 16 | 168 | $29 | $50 |
| Above-ground cartridge pump | 600 W | 8 | 144 | $24 | $43 |
Find your own wattage on the motor nameplate. If it lists amps and volts instead, multiply them — 8 amps at 230 volts is about 1,840 watts. If your utility charges time-of-use rates, moving the main filtration block into the off-peak window costs nothing and can cut this line by a third.
Chemicals
For a typical 20,000-gallon residential pool, budget roughly $25 to $60 a month across the swimming season. Chlorine is the bulk of it; the rest is pH and alkalinity adjusters, occasional shock, stabilizer, and algaecide if you use it preventively.
| Item | Typical seasonal use, 20,000 gal | Rough cost |
|---|---|---|
| Chlorine tablets or liquid | Continuous, all season | $150 to $350 |
| Shock | Weekly to fortnightly, plus after storms | $60 to $150 |
| pH and alkalinity adjusters | As testing dictates | $40 to $100 |
| Stabilizer (cyanuric acid) | Occasional top-up | $20 to $40 |
| Algaecide | Weekly preventive dose, optional | $30 to $80 |
| Test strips or reagents | All season | $25 to $60 |
The number that moves this line most is not brand choice — it is whether you test regularly against the CDC targets of at least 1 ppm free chlorine and pH 7.0 to 7.8. Chasing a problem after it has developed costs several times what preventing it does, and an algae bloom can put an extra $80 of shock into a single week. Target ranges are in pool water chemistry.
Water and evaporation
Evaporation is invisible on the bill until you work it out. A typical uncovered outdoor pool loses in the region of a quarter of an inch of depth a day in warm, dry, breezy weather. Worked for a 16 by 32 foot pool, which is 512 square feet of surface:
- 0.25 inch = 0.0208 feet. 512 × 0.0208 = 10.7 cubic feet per day
- 10.7 × 7.48 gallons per cubic foot = about 80 gallons per day
- 80 × 30 = 2,400 gallons per month
- At a combined water and sewer rate of $4 per 1,000 gallons: about $10 per month
Utility rates vary hugely by municipality, so check your own bill for the per-1,000-gallon figure. Also worth knowing: filling a 20,000-gallon pool from scratch at that same rate is about $80 in water, which is why draining and refilling to fix high cyanuric acid is an expense worth avoiding through better tablet discipline. Backwashing a sand filter adds a few hundred gallons each time; vacuuming to waste can move thousands.
A solar cover cuts evaporation substantially and pays for itself on this line alone within a season or two on most pools. The comparison is in the best pool solar covers.
Heating: the line that dwarfs the others
If you heat, everything above becomes a rounding error. The two common systems cost very different amounts to run.
| Gas heater | Electric heat pump | |
|---|---|---|
| How it works | Burns fuel to add heat directly | Moves heat from the outside air into the water |
| Speed | Fast — raises temperature in hours | Slow — 24 to 72 hours for a meaningful rise |
| Typical draw | 200,000 to 400,000 BTU/hr of fuel | 4 to 7 kW electrical |
| Rough cost per running hour | $3 to $8 on natural gas; considerably more on propane | Around $0.70 to $1.20 at $0.17/kWh |
| Best use | Occasional, on-demand heating | Holding a temperature through the season |
| Cold-weather limit | Works at any air temperature | Efficiency falls sharply below about 50°F |
Two practical points follow. First, a heat pump costs far less per hour but runs for many more hours, so the monthly bill is not automatically lower — it depends on whether you are holding a temperature or raising one. Second, and more important: a cover is worth more than any efficiency upgrade on a heated pool, because evaporation is the dominant way an outdoor pool sheds heat. Heating an uncovered pool overnight is close to heating the yard. The options are compared in pool heating options.
Everything else
| Item | Frequency | Typical cost |
|---|---|---|
| Filter media — sand | Every 5 to 7 years | $100 to $250 |
| Filter media — cartridges | Every 2 to 5 seasons | $40 to $150 each |
| Salt cell replacement | Every 3 to 7 years | $400 to $900 |
| Pump replacement | Every 8 to 12 years | $500 to $1,500 installed |
| Vinyl liner | Every 8 to 15 years | $1,500 to $4,500 installed |
| Opening and closing service | Twice a year, optional | $250 to $600 each |
| Weekly pool service | Weekly, optional | $100 to $250 a month |
| Homeowners insurance increase | Annual | Varies; ask your insurer directly |
These are the costs that surprise people, because they arrive in lumps rather than monthly. Setting aside a modest amount each month against liner, pump and heater replacement turns a $2,000 shock into a planned expense.
Where the savings actually are
- Upgrade to a variable-speed pump. Nothing else on this page comes close. Check for a utility rebate first.
- Cut pump hours to what circulation actually requires, not a habit — but do not starve the pool, because an algae bloom costs more than the electricity saved.
- Use a solar cover, and use it consistently. It saves water, chemicals and — on a heated pool — a great deal of heat.
- Shift the pump to off-peak hours if your utility has time-of-use pricing.
- Test twice a week. Prevention is dramatically cheaper than recovery.
- Keep the filter clean. A clogged filter makes the pump work harder for less flow, which costs money on both ends.
Costs are illustrative and stated as of 2026 at a representative $0.17 per kWh and $4 per 1,000 gallons. Energy and water rates vary widely by state and utility, so run the arithmetic with the numbers on your own bill.
Where to go next
The pump line is where the money is — see variable-speed vs single-speed pool pump and how many hours a day to run a pool pump. For the heating side, pool heating options. Chemistry costs drop when the numbers are right: pool water chemistry. And saltwater vs chlorine covers the running-cost trade between the two sanitation systems. Everything else sits under the pools and spas hub. Our research method is on how we rank.