Yes, pressure washer relies on only one thing – water! And pressure washers are extremely efficient both I cleaning and water consumption.
People end up saying pressure washers are water wasting monster! I mean, really? They either know nothing about pressure washing or do not understand how it works. These are the people who love to stick with their garden hose only.
This is why I decided to answer this question: How much water does a pressure washer use?
I am going to show you facts and true AF calculation that you’ll love to do with your pressure washer. Let’s do this!
An average pressure washer uses approximately 08 gallons (30.283 Litres) of water per minute. A pressure washer with 1.0-4.0 GPM (gallons per minute) is considered as good for a pressure washer. Higher the PSI is, the more efficient the pressure washer is while water consumption. With 1.7 GPM and 2000 PSI pressure washer, around 50 gallons of water is used pressure washing a car.
A pressure washer can reduce water consumption by half compared to a garden hose.
How Much Water Does A Pressure Washer Use? (With Calculation)
For reference, a garden hose uses 5-10 GPM water with 30-50 PSI. Please remember, the flow depends on water pressure which is PSI. So, here we can see the total cleaning unit(CU) is a maximum of 10 GMP X 50 PSI = 500 CU.
On the other hand, a pressure washer with a rating of 1.6 GPM and 1700 PSI generates 2720 cleaning units (CU). Which is 81.6% more cleaning capacity than an ordinary garden hose, even with a much higher GPM.
Here are some examples:
- 1.0 GPM and 1500 PSI = (1.0 X 1500) = 1,500 CU
- 1.3 GPM and 1700 PSI = (1.3 X 1700) = 2,210 CU
- 1.7 GPM and 1800 PSI = (1.7 X 1800) = 3,060 CU
- 2.5 GPM and 2100 PSI = ( 2.5 X 2100) = 5,250 CU
- 2.8 GPM and 2600 PSI = (2.8 X 2600) = 7,280 CU
As you can see, a small change in GPM and PSI can increase the amount of cleaning unit by a huge margin. Clearly, a higher GPM rating increase the pressure washing capacity to an extend but PSI plays a vital role here.
The higher the PSI the more water will be consumed with an increased flow rate. This does increase the chance of water wastage but this does increase the CU by a huge margin. Increased cleaning unit reduces the time required for cleaning. As a result, you can clean more area with less amount of time.
GPM is totally dependent on time. Thus, the more time you let the water flow the more water you consume. PSI only increases the water force.
Does Pressure Washing Increase Water bill?
I have done the water consumption calculation for you. You do the math.
For example, San Diego costs about $11 per 750 Gallons of water.
A typical pressure washer uses 2.5 gallons of water per minute. Let’s say you pressure washed a whole house which took you two hours or 120 minutes. So, a total of 300-gallon water is used. That costs less than $5.
So, no you can never say pressure washer increased your water bill.
Pressure Washer GPM vs PSI
If you have gone through the above discussion, you will agree that GPM and PSI both are important. Let’s learn more about them to find the real player here.
GPM (Gallons per Minute) is flow rate, the amount of water delivered by the machine in a minute. PSI (Pressure per Square Inch) refers to the amount of pressure created by the equipment. Cleaning Unit (CU) is defined as GPM X PSI.
A pressure washer with 1.3 GPM and 1700 PSI = (1.3 X 1700) = 2,210 CU
We have talked about these with examples above. So, we are going to talk about facts now.
When it comes to cleaning capacity of a pressure washer we assume the time taken for finishing a job. The lesser the time the higher the efficiency is.
There are different kinds of surfaces with different kinds of contaminants. This is the only reason that some people get a great result but others don’t with the same pressure washer.
For example, Grease on Teflon requires different cleaning pressure than grease on concrete. Agreeing on this we can count a single pressure washer for both situations. When the pressure washer reaches its peak pressure point, there’s only one thing to differ them.
“The flow rate or GPM or capacity of replacing debris from the cleaning area”
Water pressure from a pressure washer can only remove debris or spot from that place but it requires a water flow to wash that debris away. This is a simple explanation of why GPM is more important.
The higher the flow rate the more rapidly the dirt are cleaned. This is where the calculation of the cleaning unit (CU) comes into play.
Let’s assume a Sun Joe XPX 3000 pressure washer with 1.76 GPM and 2030 PSI competes with Stanley SHP2150 pressure washer with 1.4 GPM with 2150 PSI.
The Stanley has an edge over sun joe in PSI. But, do the math.
- 1.76 X 2030 = 3,572 CU
- 1.40 X 2150= 3,010 CU
The Sun Joe is the definite winner despite shorter PSI. This is why the flow rate is so crucial while measuring pressure washer efficiency.
So, if you were asking “is more GPM better for pressure washer?” I hope you have your answer.
A powerful pressure washer can clean any kind of surfaces with ease. Standard pressure washer ranges between 1.0-4.0 GPM and 1700-2500 PSI. I have an article on electric pressure washers for all-purpose uses.
Moreover, for only washing a car you’ll not need a heavy pressure washer. I have mentioned some pressure washers fit for car washing in this article.
You have to pressure wash properly to save water. Most of the time wrong use of this equipment results in a waste of water.
Source: Simpson GPM guide