If you’re in the market for a pressure washer, then you will have seen that there is a lot of different stuff to learn before buying.
Between different nozzle types, electric washer vs petrol washer, how to care for it, it can easily become overwhelming already.
On top of that, you also need to know a bit about the pressure output of the washer you want and what kind of pressure you need to do the cleaning you want.
Pressure washers come with a range of different pressure outputs (measured in psi). In general, you can match the pressure to the sturdiness of the surface you’re cleaning. Lower pressures are best for fragile surfaces, medium/middle pressures for more durable surfaces that you might clean regularly and the highest pressures are best for more niche situations like stubborn grime/stains.
What is psi?
If you’re reading this and already feel lost, then don’t worry, we’ll be starting at the beginning!
Psi, which stands for pounds per square inch, is one of the units we use to measure pressure. You’ve probably come across it in other areas like bicycle or car tyre pressures.
Pressure is sometimes also quoted in bars (1 bar, 2 bar etc.) but it’s possible to easily compare and convert between the two (like switching between inches and centimetres).
It’s tempting to think that a higher pressure is just overall better for your pressure washer. But there’s another factor to think about when picking the washer and that’s water flow.
Water flow is how much water is actually being sprayed out by the pressure washer and is measured in gallons per minute (gpm).
The best cleaning power and efficiency will come from matching these two characteristics to each other in a beneficial way.
Having a really high pressure will certainly break up dirt and grime, but without enough water being sprayed out to back it up, the dirt is liable to just sit there. You need a high enough gpm to wash away the dirt that you’ve broken apart.
The perfect combination of these two numbers will give you the most efficient cleaning with your washer, giving you lower cleaning times while still maintaining good water force.
Pressure washers have a large range of advertised pressures but they can be divided into three categories: light duty, medium duty and heavy duty.
Each one will be more suited to different cleaning tasks.
It can be hard to contextualise different pressure outputs, but to put it into perspective, a regular garden hose is about 60 psi.
With that in mind, let’s look at some of the pressures and what they can do!
Light duty (low psi) pressure washers
These pressure washers give the lowest maximum pressure output. Generally, a light duty pressure washer will reach pressures of around 1500 psi.
These are almost exclusively electric powered washers, which can mean they’re generally much smaller and lighter, meaning they’re easier to move around (as long as you can plug them in while using them).
A low psi pressure washer is great for washing more fragile surfaces such as windows (though for these, a much lower pressure is best), garden furniture, BBQ’s, washing out bins and even cars and bicycles.
They’re especially great for cars and bicycles, since a lot of the surfaces on cars require lower pressures (such as tyres, windows, lights).
The lower psi pressure washers are also cheaper in general, due to the lower maximum output, but if you’re buying one of these then it’s likely you wouldn’t be using it heavily, making it a sound investment.
Due to the nature of these being electric, they do not require much maintenance either, meaning you can get them out and they’ll be pretty much ready to go for a quick car clean.
If you need to cover a large area with water, a light duty washer is unlikely to be able to manage this effectively, as adding a wider nozzle to the washer will lower the pressure, giving you a weaker spray.
Medium duty (middle psi) pressure washers
The next step in pressure washer psi comes from the medium duty washers. While the low duty washers usually max out at about 1500 psi, these washers can range from 1500 to about 2800 psi.
These washers are the most commonly bought washers, as they are applicable to a lot of the different surfaces that you would have outside which need regular cleaning.
Again, these washers come in electric powered varieties, meaning good mobility.
A medium duty pressure washer will be great for washing larger areas than a light duty washer. Patios, driveways, fencing, decking and walls are all able to be washed effectively with a medium duty pressure washer.
Combining the higher pressure with a wide nozzle will let you cover a wide area with water quickly, as the higher pressure compensates for the reduced pressure that comes with a wide spray nozzle.
If used on their highest pressure setting, these pressure washers will be able to deal with some of the more stubborn stains and dirt that can be found around the home.
These washers will be useful for most people with outside spaces with large areas that need regular cleaning and they are pretty versatile.
Heavy duty (high psi) pressure washers
And now we come to the heavy duty washers. These washers have the highest pressure output and can be very powerful pieces of kit.
The higher pressures can easily exceed 2800 psi and some even go up to 4000!
To power these washers, electric power doesn’t cut it, so these are powered with petrol or diesel engines. This will limit their mobility as they’re generally a lot heavier, and you need to carry a fuel canister around with you.
These washers are a bit more niche, as it’s unlikely that you’ll have anything dirty or stubborn enough to need that much power.
Again, large surfaces are easy with these washers. They can cover a large wall in no time.
A heavy duty washer is even powerful enough to strip rust from metal!
A further use of these washers is to strip paint from surfaces. If you’re thinking of upgrading a paint job around your garden, then this is a good choice as you’ll be able to easily remove the old paint and clean the surface before applying a new paint job.
These washers are, however, the most expensive variety, so they’re only worth buying if you’re really sure!
And hopefully that’s made things a little clearer!
A medium duty washer will probably suit most of your cleaning needs as you will get the benefit of a light duty washer as well (if you want lower pressures, you can use a wider nozzle).
Medium duty washers are definitely the most versatile and, unless you have some serious grime or rust you need to get rid of, will perform most of your cleaning tasks quickly and effectively, which is all you really need!