Pressure washer PSI seems like an important metric, but what PSI is really needed for a typical homeowner? In this article, we will cover the basics of PSI and GPM, the reliability of PSI ratings, whether purchasing a small PSI or GPM pressure washer is worth it, and recommendations for PSI and GPM.
The basics of PSI and GPM
PSI, or pounds per square inch, is a metric that is widely understood to mean the “power” a pressure washer has. This is often seen as the only useful metric when deciding on what pressure washer to get by many, although it is not the only (or the most) important metric.
GPM is another, arguably better, metric that pressure washers have. GPM stands for gallons-per-minute and is a rating that assesses how much water the pressure washer pump can handle per minute.
PSI is measured at the nozzle as the water immediately leaves the machine. As the pressurized water travels further from the nozzle and spreads out, the PSI rating is reduced. The less water is coming from the nozzle, the greater this reduction can be.
A pressure washer PSI is an important metric to be sure, but GPM is going to really make the difference on the quality, abilities, and speed of the pressure washer being assessed. Above a certain value, PSI is irrelevant and GPM is going to make the difference with residential pressure washing needs.
“PSI normally isn’t as important as the flow of water. Using lower PSI and higher flow will allow the home to be cleaned safely using low pressure” - Nicholas Flemion, Central Virginia Power Wash
PSI and GPM both play a part in how long a pressure washing task will take. For more information on this, read our article How Long Does Pressure Washing Take?
The reliability of PSI ratings
Unfortunately, PSI ratings cannot be trusted from anyone but the very top brands. If a pressure washer is being purchased on Amazon or anywhere online and it is a no-name brand, the PSI ratings are almost certainly fake and unreliable. As a general rule of thumb, in 2024, a pressure washer less than $100 is not going to have more than 2000 PSI, which is barely enough to wash a driveway.
Simpson, a trustworthy(ish) brand, is largely on point with PSI ratings and they sell 2800 PSI units for approximately $500 in 2024.
M-iT-M, another trustworthy brand, is almost always exactly correct with PSI ratings and sells 2800 PSI pressure washers for upwards of $700 in 2024.
If it seems like the PSI rating is too good to be true for the price, it is. Pressure Washer manufacturers employ plenty of tricks to mislead consumers about the power of their machinery.
Is purchasing a small PSI or GPM unit worth it?
For basic pressure washing tasks around the house, a pressure washer with less than 2500 PSI and a 2.0 GPM flow is essentially a garden hose extender. It will struggle to clean algae from siding, dirt from concrete, and flaking paint. Even if you can get it to work, it will take significantly longer and more effort to have a similar result to a pressure washer at or above the 2500 PSI and 2.0 GPM mark.
Unless you are only getting a pressure washer to clean a boat or a car, a small unit won’t cut it and will take up valuable space in your garage. Renting a larger unit or hiring a professional could be a cheaper method. For more on this, read our article on Renting a Pressure Washer here.
PSI and GPM recommendations
For tasks around the house, a pressure washer from a reputable brand, with 2500+ PSI and 2.0+ GPM will be perfectly suitable. As the PSI goes up, it diminishes in extra utility at about 3500 PSI. Above this mark there is no extra advantage from a speed perspective and almost anything around the house can be removed at about 3500 PSI.
For GPM, more is better up to 4.0 GPM. This is because most residential exterior water spigots will only release four gallons per minute so any additional pump capacity will require an exterior water tank with large hoses. This is a huge inconvenience and many pressure-washing companies will avoid such large pump capacity. If you are interested, check out our article Do Pressure Washing Companies Use My Water for more info on GPM ratings.
PSI is certainly an important metric when picking which pressure washer is right for you. While it is not the only important measurement, make sure the pressure washer is from a brand you can trust and will suit your exact needs. If hiring a professional seems to be the right decision for you, please contact EcoWash.