Water Pressure PSI Guide

Water Pressure PSI Guide

How to Choose the Right PSI for Your Pressure Washer

Pressure washer shoppers often ask how much pressure they really need from a pressure washer, and the answer is: it depends on your project. The pressure put out by a power washer is measured in PSI (pounds per square inch), and the PSI requirements can vary based on what you need to clean.

For example, it'll take a lot less pressure to clean dirt and salt from your vehicle than it will take to clean oil stains from your garage floor. Another factor that's equally as important, but not often considered, is the gallons per minute rating (GPM). This measures how much water your pressure washer puts out per minute, and more water equals faster cleaning.

How Much Pressure Does It Take?

Pressure Washing on a Sidewalk

When determining what range of PSI you want from a pressure washer, there are two general schools of thinking. The first is, buy for the pressure you'll eventually want because you can dial the pressure down enough to handle any lesser project, and you'll benefit from the 'buy it right and buy it once' effect, instead of later upgrading down the road.

If, for example, you want a pressure washer to clean your car, but later realize you want to use it to clean your driveway, remove stains, and strip paint, the ranges of PSI recommendations are very different, and you might be disappointed when yours isn't powerful enough to handle the job efficiently.

PSI and GPM Comparison Chart 
On the other hand, if you're never going to exceed 2,500 PSI for your projects, then you can save some money by choosing a 2,600 PSI pressure washer over a 4,000 PSI pressure washer. Remember that pressure ranges are variable - in other words, there isn't always a noticeable difference between 1,500 and 1,600 PSI, and you should always start with lower pressure recommendation and work your way up, instead of starting at the upper end of a recommended PSI range and risk damage to whatever you're cleaning.

The list below has some recommended PSI ratings for a few common household cleaning projects.

Pressure Washer PSI Chart
Shop Pressure Washers by PSI

How Much Water Flow Does It Take?

Pressure Washing Sidewalk

While water pressure provides the power to break up stains and dirt, water volume is what flushes that broken-up filth away.

Essentially, the more water that moves through your nozzle in a minute, the faster you'll be able to clean. Greater GPM (gallons per minute) cleans quicker because there's more flowing water present to lift and carry away the dirt.

Imagine a garden hose that is flowing. On its own, you've got flow for wetting, but not pressure for cleaning. Now apply your thumb over the end of the hose, and you can wash clumps of dirt off your driveway or sidewalk. This principle applies to PSI and GPM: if you can combine the pressure of your thumb (PSI) with the volume of the hose (GPM), you'll have a great cleaning tool. Pressure washers allow you to do just that, combine high pressure with high volume to clean stubborn surfaces in record time.

GPM relation to Cleaning Time

Why PSI Matters When Using Attachments

Attachments make pressure washing more efficient and effective, and as a result, more fun to use. Choosing the right accessories can make all the difference for your cleaning project(s).

For example, a surface cleaner has minimum requirements with GPM in order to properly dispense water during cleaning jobs at the rated PSI. Can you use one with pressure washers that don't meet that requirement? Maybe. But doing so would greatly diminish performance, and might leave you thinking the surface cleaner doesn't work, when in fact it just wasn't being supplied the correct amount of water.

Pressure Washer TipsSimilarly, choosing the proper tips and attachments will directly impact your PSI results as well. Below is a helpful orifice sizing chart that helps determine which tips can adequately deliver the proper desired PSI ratings. Here's how to choose the right spray tip for your pressure washer.

While different tips allow different angles of pressure, the orifice size matters here because it determines which tips will fit on your pressure washer lance in order to clean. This is the same as when you are attaching a turbo nozzle, extension lance, or other similar attachment. The numbers illustrated in the chart below refer to the orifice size the tips are in order to attach to your pressure washer lance. Example: 4,000 PSI at 3 GPM requires an orifice size of "3" to attach properly.

Pressure Washer Nozzle Orifice Chart

Frequently Asked Questions

There are many questions people often ask about pressure washers, so we created an article to capture the most commonly asked questions and provide answers with context. Please read our FAQ article for more information.

 NEXT: Frequently Asked Questions About Pressure Washers

Jim, the Pressure Washer Expert
Pressure Washer Expert
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