How much water does a pressure washer use?
Before you make your decision on what pressure washer to buy, it’s worth considering just how much water a pressure washer uses. This is a relevant question, from both cost and environmental grounds. The only way I can see of making an easy comparison is by comparing pressure washer water usage with hose pipe water usage.
How Does A Pressure Washer Work
A pressure washer works by means of an electric pump that forces water supplied via a hose pipe from the mains through a small nozzle at high speed. The smaller the nozzle, the more power the water jet has. The strong water jet is used to dislodge dirt and debris, if needed most power washers have detergent attachments which allow you to remove stubborn stains using detergent.
Pressure Washer Vs Garden Hose
Most people use a garden hose to wash down their patio or driveway, and also to wash their car. And at face value it would appear to be a water efficient way to clean your property, but the facts stack up against it.
The average garden hose uses around 20 gallons of water per minute whereas the average water usage for a pressure washer is 2 gallons of water per minute, according to the Long Beach Water Department.
A garden hose is powered by the amount of pressure that water leaves the tap with. This is on average between 30-50 Pounds Per Square Inch (PSI). A pressure washer averages between 1750-2600 PSI.
So using a pressure washer potentially gives you anywhere between 5-18% more power and uses 68% less water. Saving you time, money and water.
How Much Water Does A Pressure Washer Use Per Minute
This is dependent on the make and model of pressure washer used, but the average amount of water used by a pressure washer is around 1.6 gallons per minute (GPM). It’s not the quantity of water used that cleans away dirt and debris, it’s the amount of pressure that water is projected at the dirt.
If we take a medium duty DIY home pressure washer, which has a flow rate of between 2-2.5 GPM and compare this with an average shower head, that averages around 2.5-3 GPM you can easily see it’s not the amount of water that’s important it’s the amount of pressure that water is under.
As stated earlier, a garden hose has a typical pressure rating of between 30-50 PSI and the average pressure washer has an average pressure rating of around 1750-2600 PSI. Putting all this information into practical terms, let’s look at individual tasks and see if we can work out how much water they use.
How Much Water Does A Pressure Washer Use To Wash A Car
If it takes around 20 minutes to wash a standard car using a hose, with an average water usage of 8 GPM, that equates to 160 gallons of water. Doing the same task using a regular pressure washer, would use around 40 gallons of water. Just to make that crystal clear, using a pressure washer to wash your car could save you 75% of the water you would use if you washed the car using a hosepipe.
How Much Water Does A Pressure Washer Use To Clean A Patio
This is not an easy question to answer accurately without knowing the size of the patio, what it’s made from, and how dirty it is. Other considerations include what the stains are from (grease will be harder to remove than general dirt), how dirty the patio is etc.
Let’s assume it’s a standard size patio, that takes around half an hour to pressure wash clean, that would use around 60 gallons of water, at a rate of 2 GPM with the calculation being
2GPM X 30 minutes = 60 gallons
How Much Water Does A Pressure Washer Use To Clean A Driveway
This is again one of those questions with many variables affecting the answer. It is dependent on the size and shape of the driveway, what material it’s made from and how dirty it is. Plus what the stains came from, grease and oil will take longer to remove than just dirt, debris and moss.
But assuming it’s a standard size driveway with average amounts of dirt and debris, it will usually take an hour to power wash clean, which would use around 120 gallons of water at the 2GPM as before with the calculation looking like this:
2 GPM x 60 minutes = 120 gallons
This might sound a lot but if we consider that the garden hose has a 20 GPM flow rate, that figure would be a whopping 1,200 gallons for the same driveway.
Does Pressure Washing Waste Water
As we have seen above, pressure washing uses on average 10 times less water than a garden hose to do the same jobs. So even though it looks like pressure washers use a lot of water they are in fact saving water.You can even use water from other supplies, not connected to the main water supply at all.
Water Butts
Many pressure washers have the ability to suck water up via a length of pipe that is placed into the water butt. This allows you to use collected rainwater in your pressure washer, thus saving water and costing you less too.
Buckets
Most pressure washers have the ability to use water from a standard bucket via a short length of hosepipe. This allows you to keep absolute control on the amount of water you are using.
Wells
Some people are fortunate to have a well in their garden, as long as the pipe is long enough, it is possible to use the well water in your pressure washer.
How Much Pressure Is Safe
Some surfaces can be damaged with too much pressure, wood for instance, when wet can easily flake if too much water pressure is applied to it. So how much is too much?
| Type Of Surface | Maximum PSI |
|---|---|
| Car | 1900 |
| Concrete Driveway | 3000 |
| Wooden Decking | 1500 |
| Block Paving | 1500 |
| Wooden Fencing | 1800 |
| Vinyl Fencing | 1800 |
| House | 3000 |
| Asphalt | 1800 |
| Metal Garden Furniture | 3000 |
| Railings | 1500 |
The pressure ratings in the above guide are the maximum PSI for each task, it is not recommended to exceed these limits. Most pressure washers can have the pressure per square inch lowered by either fitting a different nozzle or by adjusting the spray flow.
Be careful when using a pressure washer on a house, as old mortar can disintegrate under the power of water from a pressure washer, always check the integrity of the building before use. It’s best to use a lower than recommended pressure for pressure washing houses for reasons of safety.
