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A consumer pressure washer uses 1.2 to 2.6 gallons per minute — far less than the 8 to 17 gallons per minute an open garden hose delivers. A standard 1.76 GPM electric machine consumes about 106 gallons per hour of trigger time; a 2.5 GPM gas machine about 150. Because a washer also finishes the job several times faster than a hose and a brush, the total water used per car, deck or driveway is typically one third to one fifth of the hose equivalent.
Flow Rate by Machine Class
| Machine class | Typical GPM | Gallons per hour | Gallons per 15 minutes |
|---|---|---|---|
| Compact electric (1,600–1,900 PSI) | 1.2–1.4 | 72–84 | 18–21 |
| Mainstream electric (2,000–2,500 PSI) | 1.76 | ~106 | ~26 |
| High-end electric (3,000–3,400 PSI) | 1.76–2.0 | 106–120 | 26–30 |
| Residential gas (3,000–3,400 PSI) | 2.3–2.6 | 138–156 | 35–39 |
| Prosumer gas (4,000+ PSI) | 3.5–4.0 | 210–240 | 53–60 |
| Cordless / battery | 0.6–1.0 | 36–60 | 9–15 |
| Open 5/8-inch garden hose | 8–17 | 480–1,020 | 120–255 |
Read the bottom two rows together and the point becomes obvious. The pressure washer is not a water-hungry appliance — it is a water-efficient one. It gets its cleaning ability from pressure, so it needs far less volume than a hose that relies entirely on flooding a surface.
Note also that these are trigger-time figures. Most machines have a total-stop system, so water only moves while the trigger is held. Across a real session, actual trigger time is usually 50 to 70 percent of elapsed time, because you are moving the hose, changing tips, applying detergent and waiting for it to dwell.
Water Used by Job
Working from typical trigger times on a 1.76 GPM electric machine:
| Job | Trigger time | Water used | Hose equivalent |
|---|---|---|---|
| Wash one car | 10–15 min | 18–26 gal | 80–140 gal |
| Patio furniture set | 10 min | ~18 gal | 60–100 gal |
| Two-car driveway (600 sq ft) | 60–120 min | 105–210 gal | Impractical with a hose |
| 400 sq ft deck | 45–60 min | 80–105 gal | 250+ gal |
| Single-story house wash | 90–150 min | 160–265 gal | Impractical with a hose |
| Two-story house wash | 3–4 hours | 320–420 gal | Impractical with a hose |
For scale, the EPA notes that the average American family uses more than 300 gallons of water per day at home, with roughly 30 percent of that going to outdoor use. A whole-house wash, then, is about one day of normal household consumption — and it happens once every one to three years.
What the Electricity Actually Costs
This is the second half of the running-cost question, and the answer is reassuring.
An electric pressure washer with a 13 to 15-amp motor on a 120V circuit draws roughly 1,500 to 1,800 watts — comparable to a hair dryer, a toaster or a small space heater. One hour of continuous running is therefore about 1.5 to 1.8 kilowatt-hours.
US residential electricity averages somewhere around 17 cents per kilowatt-hour nationally as of 2026, according to the Energy Information Administration's monthly retail price table, though state variation is enormous — from roughly 11 cents in parts of the South to well over 40 cents in Hawaii and California. At the national average:
| Session | Energy used | Cost at 17¢/kWh |
|---|---|---|
| 15 minutes (one car) | 0.4–0.45 kWh | 7–8 cents |
| 1 hour trigger time | 1.5–1.8 kWh | 26–31 cents |
| Half-day driveway job | 3–4 kWh | 51–68 cents |
| Full house wash | 4–6 kWh | 68 cents–$1.02 |
So no, pressure washers do not use a lot of electricity. What they do demand is current, all at once. A 15-amp motor on a 15-amp household circuit is running near the limit, so plug into a dedicated outdoor circuit, avoid sharing it with anything else, and if you must use an extension cord, use a heavy outdoor-rated one — 12 gauge for anything over 25 feet. Undersized cords are the most common cause of a machine that "keeps tripping the breaker" or "lost power after a few minutes".
Gas machines, for comparison, burn roughly 0.4 to 0.6 gallons of fuel per hour on a 200 to 220cc engine. At $3.50 a gallon that is about $1.40 to $2.10 per hour — several times the electric running cost, though still small against the time saved on a big concrete job.
Will Your Faucet Keep Up?
This is the water question that actually causes problems. A pressure washer must be fed at least as fast as it consumes, or the pump starves — and a starved pump cavitates, which damages it quickly.
To check your supply, run your outdoor faucet wide open into a five-gallon bucket and time it. Under 40 seconds means roughly 7.5 GPM or better, which is comfortable for any consumer machine. If it takes over a minute, you have under 5 GPM and should be cautious with a high-flow gas unit.
Three things throttle supply more often than the faucet itself: a kinked or undersized inlet hose, a clogged inlet screen at the pump — check and rinse it, it is the most-missed maintenance item on these machines — and a long, narrow garden hose. Use a 5/8-inch or 3/4-inch supply hose, keep it as short as practical, and open the faucet fully before starting the machine.
Using Less Water Still
- Let detergent do the work. Chemistry and dwell time reduce trigger time more than any technique change.
- Use a surface cleaner on flat areas. It cleans a full swath per pass instead of a strip, cutting driveway trigger time by roughly two thirds.
- Sweep before you wash. Never use water to move debris a broom can move.
- Match the tip to the surface. A wrong tip means going over the same area repeatedly.
- Direct runoff to a lawn or bed rather than a storm drain, so the water at least irrigates something.
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