TL;DR
Pressure alone does not clean; flow does half the work, so compare PSI and GPM together rather than chasing the biggest pressure number. For most home exteriors, 1,800 to 2,800 PSI at 1.5 to 2.5 GPM is plenty, and the nozzle you choose matters more than the machine's top rating.
PSI and GPM Do Different Jobs
PSI is the force the water hits with. GPM is how much water arrives per minute. Cleaning needs both, because pressure breaks the bond between dirt and surface while flow carries the dirt away.
A machine with high pressure and low flow blasts a narrow stripe and leaves you standing there. A machine with moderate pressure and good flow covers ground.
Multiplying the two gives a rough comparison figure sometimes called cleaning units. It is a blunt tool, but it stops you from paying for pressure you cannot use.
What PSI Do I Actually Need for Home Exteriors?
Most home jobs sit in the 1,800 to 2,800 PSI range at 1.5 to 2.5 GPM. That handles concrete driveways, walkways, patios, fences, and outdoor furniture without difficulty. Higher ratings from 2,800 to 4,000 PSI are aimed at heavy concrete, commercial work, and paint stripping, and they will damage most residential siding.
Siding, in fact, usually needs far less pressure than people apply. Soft washing, which uses low pressure with a cleaning solution and dwell time, is the correct approach for painted siding, stucco, and anything with a coating.
Roof surfaces should not be pressure washed at all. High pressure strips the granules off asphalt shingles and drives water under them.
Electric Versus Gas
Electric machines typically deliver about 1,300 to 2,300 PSI at 1.2 to 1.6 GPM. They are quiet, need no fuel or oil, start instantly, and can be used on a covered patio. Their limit is flow, so large areas take longer.
Gas machines typically deliver about 2,500 to 4,000 PSI at 2 to 4 GPM. They cover ground much faster and require fuel, oil changes, and outdoor-only operation because of exhaust. They are also heavy.
For a typical suburban lot with a driveway, a patio, and a fence, an electric unit in the upper part of its range is usually enough. If you have long stretches of concrete, gas will save real hours.
Check the pump type too. Axial cam pumps are common on consumer machines and are generally not rebuildable. Triplex pumps cost more, run cooler, and can be serviced, which matters if you will use it heavily.
What Do the Pressure Washer Nozzle Colors Mean?
Nozzles are color coded by spray angle, and the angle changes both force and coverage. Red is 0 degrees, a pinpoint jet that concentrates all force in one spot. Yellow is 15 degrees for stripping and heavy concrete. Green is 25 degrees, the general-purpose tip. White is 40 degrees for gentle rinsing and delicate surfaces. Black is a low-pressure soaping tip that lets the machine draw detergent.
The red 0-degree tip is the one to leave in the box. It concentrates enough force to cut into wood, gouge concrete, and injure skin, and it cleans a stripe so narrow it is impractical anyway.
A rotating or turbo nozzle spins a 0-degree jet in a cone, which gives the coverage of a wide tip with more bite. It is aggressive and will mark soft surfaces, so test it somewhere hidden.
A surface cleaner attachment, essentially a spinning bar under a shroud, is the single best add-on for driveways and patios. It cleans evenly without the striping that a wand leaves behind, and it commonly runs about $60 to $200.
Safety Rules That Are Not Optional
A pressure washer is not a garden hose with attitude. The stream can cause a serious injection injury that looks like a small puncture and needs immediate medical attention.
- Never point the wand at a person or a pet, even briefly.
- Never use the 0-degree tip on any surface you care about.
- Never spray up under lap siding, which drives water behind it.
- Keep the stream away from window glass, screens, light fixtures, outlets, meters, and vents.
- Wear eye protection and closed shoes, and expect the wand to kick when you pull the trigger.
- Plug electric units into a GFCI-protected outlet, and keep the cord out of standing water.
- Work off a ladder only with great caution; the recoil is what causes falls. Use an extension wand from the ground instead.
Never run bleach through a machine that is not rated for it, and never mix cleaning products in the detergent tank. Bleach mixed with any acid or with ammonia releases toxic gas, and household cleaners contain both.
Features Worth Having
Hose length and quality matter daily. A 25 to 35 foot pressure hose covers most work, and a flexible non-marking hose beats a stiff one that fights you.
An onboard detergent tank with a siphon makes soap application easy, but check whether it draws only through the black tip. Most do.
Look at the wheels and the frame. A machine you have to drag across grass by the handle gets used less than one that rolls.
Total stop systems shut the pump off when you release the trigger, which extends pump life and cuts noise. It is worth looking for.
What a Pressure Washer Will and Will Not Fix
It excels on concrete, brick, pavers, fences, decks at low pressure, and outdoor furniture. It is the wrong tool for windows, screens, roofs, soft or aging wood, painted surfaces with failing paint, and anything with an electrical connection.
Organic growth on shaded concrete often comes back quickly after a pressure-only cleaning, because pressure removes the visible layer and not the biological one. A cleaning solution with dwell time before rinsing lasts longer, and we walk through the approach in exterior surface cleaning.
Glass is a separate discipline entirely, since pressure will not give you a streak-free result and can force water past seals. That job wants the tools in window cleaning kits. For water that ends up somewhere it should not, see wet dry vacuum basics.
What Pressure Washers Cost
Consumer electric units commonly run about $120 to $300. Higher-output electric and entry gas machines generally run $300 to $500. Gas units with triplex pumps and higher flow typically land in the $500 to $1,200+ range.
Renting is worth considering if you will use it once or twice a year. Daily rentals for residential machines commonly run about $50 to $110.
If exterior work is not something you want to take on yourself, our pressure washing service covers it, and our home cleaning services handle the interior side of the same house.
FAQ
What PSI do I need for a home pressure washer?
For most residential work, 1,800 to 2,800 PSI at 1.5 to 2.5 GPM handles driveways, patios, fences, and furniture. Higher ratings are aimed at heavy commercial concrete and paint stripping and will damage siding. Flow in gallons per minute matters as much as pressure for how fast you finish.
What is the difference between PSI and GPM?
PSI is the force the water strikes with, and GPM is how much water arrives each minute. Pressure breaks the bond between dirt and the surface, while flow carries that dirt away. A high-pressure, low-flow machine cleans a narrow stripe slowly; balanced numbers cover ground.
What do pressure washer nozzle colors mean?
Red is a 0-degree pinpoint jet, yellow is 15 degrees for stripping, green is 25 degrees for general work, white is 40 degrees for gentle rinsing, and black is a low-pressure soaping tip. Green and white cover most home jobs. The red tip damages surfaces and can injure skin.
Can I pressure wash my house siding?
Not with high pressure. Painted siding, stucco, and coated surfaces should be soft washed, which uses low pressure with a cleaning solution and dwell time. High pressure forces water up behind lap siding and into wall cavities, and it can strip paint. Keep the stream angled downward.
Is it safe to pressure wash a roof?
No. High pressure strips granules from asphalt shingles, shortens roof life, and drives water under the shingle course. Roof cleaning is done with low-pressure solutions rather than force, and it involves working at height. It is generally a job worth handing to someone equipped for it.
Should I buy or rent a pressure washer?
Buy if you will use it several times a year on a driveway, patio, or fence. Rent if it is a once-a-season job, since daily rentals commonly run about $50 to $110 and you avoid storage, winterizing, and pump maintenance. Renting also lets you try a higher-output machine.
Every property has different surfaces and different problems, so the right approach depends on what you are actually cleaning. If you would rather not handle the exterior work yourself, get a quote and we will walk you through the options.