Blog Post

Understanding how much water your pressure washer uses is essential—not only for managing utility costs but also for improving job efficiency and reducing environmental impact.

Whether you're a DIY enthusiast or a commercial cleaner, knowing your water usage can help you plan better and clean smarter.
 

What Determines Water Usage in a Pressure Washer?

Two main metrics determine your water usage, your pressure washer’s GPM (Gallons per minute) and your PSI (Pounds per square inch). Knowing these is essential to calculate your water usage.

GPM: Gallons Per Minute

The key metric to understand is GPM—Gallons Per Minute. This indicates the volume of water your pressure washer consumes per minute of operation. You can look up your pressure washer model to learn your exact specifications.

PSI vs. GPM

While PSI (Pounds per Square Inch) determines pressure, GPM tells you how much water is being delivered. For effective cleaning, both must work in harmony, but GPM directly affects water usage.

Nozzle Size and Type

Different nozzles affect both the flow rate and spray pattern. A wider nozzle may deliver water faster, increasing your GPM temporarily.

For more information on GPM and PSI check out our blog What PSI Should I Use for Pressure Washing?
 

What Are Cleaning Units (CU)?

When it comes to real-world performance, GPM usually plays a more significant role than PSI. The formula for Cleaning Units (CU) is:

CU = PSI x GPM

This means a lower-pressure, higher-flow machine can often outperform a high-pressure, low-flow one when cleaning large, dirty surfaces.
 

Calculating Your Pressure Washer's Water Consumption

To calculate water usage, use this simple formula:

Total Water Used = GPM x Total Minutes Used

Example: A 4 GPM washer used for 30 minutes consumes 120 gallons of water.

With that being said the key to estimating your water consumption is knowing how long it takes you to complete certain tasks and the GPM required to complete those tasks. Here are some job-based estimates:

• Driveway cleaning (1 hour @ 4 GPM): 240 gallons

• House siding (2 hours @ 3 GPM): 360 gallons
   

How Big of a Water Tank Do You Need?

If you’re operating a mobile unit like a Mud Dog Trailer , tank size is crucial. A 4 GPM unit running for an hour requires at least a 250-gallon tank with some buffer.

It is vital that you understand your average job duration, GPM used per task within that job, how/where you can refill, and how many jobs you wish to complete in a given period. Using the formula above and your estimates you should have a rough idea of how big of a tank you need.

Mud Dog Trailers custom-build systems with appropriately sized tanks—from compact builds to large-scale trailers for high-GPM jobs.
 

What Is a Reclaim System and How Does It Help?

A reclaim system is a water recovery system designed to capture used water during pressure washing, filter it, and reuse it. This dramatically reduces the overall water footprint of pressure washing operations.

At Mud Dog Trailers, we integrate cutting-edge reclaim systems into many of our trailer builds. These systems allow commercial cleaners to operate in eco-sensitive areas, meet local regulations, and save significantly on water costs over time.

Benefits of a reclaim system include:

1. Water conservation through reuse

2. Compliance with environmental regulations

3. Lower operational costs

4. Ability to work in areas without easy water access

Pressure washer water usage can add up quickly—but with the right tools and knowledge, you can clean efficiently while saving water. From understanding GPM and PSI to optimizing your tank size and embracing water reclaim systems, there are many ways to make your pressure washing more sustainable.

If you're ready to maximize efficiency, reduce water waste, and get a trailer system that’s built for your needs, check out Mud Dog Trailers . With decades of experience and a commitment to innovation, we’re the trusted name in pressure washing trailer solutions and offer prebuilt and custom pressure washer trailers perfect for any business. Call 910-759-6222 to talk to an expert today.