Is Water Flow More Important Than Pressure?

The short answer is yes.

Most people shopping for a pressure washer concentrate on the pressure (BAR or PSI) because it’s the biggest number they see in the specifications. In reality, water flow is often just as important – and for many cleaning jobs, it’s actually more important than pressure.

If you’re wondering why two pressure washers with similar pressure ratings can clean at very different speeds, the answer usually comes down to water flow.

What is pressure?

Pressure (measured in BAR or PSI) is the force with which the water hits the surface.

Think of pressure as the power that helps break dirt away from the surface.

Higher pressure can be useful for stubborn dirt, moss and heavy soiling, but pressure alone doesn’t tell the whole story.

What is water flow?

Water flow is measured in litres per minute (L/min) or litres per hour (L/hr).

Quite simply, it’s the amount of water the machine delivers.

Once the dirt has been loosened, it’s the water flow that washes it away.

Imagine trying to sweep leaves from your driveway with a drinking straw. You could blow very hard (high pressure), but because only a tiny amount of air is moving, it would take a long time.

Now imagine using a leaf blower. The air isn’t necessarily at a higher pressure, but the much greater volume moves the leaves quickly.

Pressure washers work in a very similar way.

A simple example

Imagine two pressure washers.

Machine A

• 160 BAR
• 7 litres per minute

Machine B

• 130 BAR
• 11 litres per minute

Most people immediately assume Machine A will clean faster because it has the higher pressure.

In reality, for many jobs such as patios, driveways and large vehicles, Machine B will often clean more quickly because it is delivering over 50% more water.

That extra water carries dirt away more efficiently, meaning you spend less time going over the same area.

Why professionals choose higher water flow

Professional users rarely buy a pressure washer based on pressure alone.

Car detailers, valeters, farmers and cleaning contractors know that water flow saves time.

Higher water flow means:

• Faster rinsing
• Quicker removal of loosened dirt
• Less striping when cleaning large surfaces
• Better performance with rotary surface cleaners
• Reduced cleaning time overall

When you’re cleaning all day, even saving a few minutes on each job soon adds up.

Does pressure still matter?

Absolutely.

You still need enough pressure to break dirt away from the surface.

Too little pressure can make cleaning slow and frustrating.

However, once you reach a sensible level of pressure, increasing the water flow often gives a bigger improvement in real-world cleaning performance than simply increasing the pressure.

The ideal pressure washer combines sufficient pressure with generous water flow.

Which matters more for different jobs?

Washing cars

A moderate pressure with good water flow is usually ideal. Plenty of water helps rinse shampoo and dirt away safely without relying on excessive pressure.

Patios and driveways

Both pressure and water flow are important, but good water flow will usually allow you to clean larger areas much faster.

Agricultural and commercial cleaning

Water flow becomes increasingly important. Heavy dirt needs washing away quickly, and larger pumps delivering more water can make a dramatic difference in productivity.

Our advice

One of the biggest mistakes we see is customers comparing pressure washers using only the BAR figure.

Manufacturers know that bigger numbers attract attention, which is why pressure often receives the most publicity.

Our advice is to look at both the pressure and the water flow before making a decision.

A well-built pressure washer with slightly lower pressure but higher water flow will often outperform a machine with impressive pressure figures but a lower water output.

Need help choosing?

Every customer uses their pressure washer differently.

Some mainly wash cars, others clean patios every weekend, while some need a machine capable of daily professional use.

If you’re unsure which model is right for you, we’re always happy to help. Tell us what you want to clean, how often you’ll use it and roughly how long each cleaning session lasts, and we’ll recommend the most suitable pressure washer for your needs—whether that’s a Kranzle or another machine that better suits your requirements.

Choosing the right specification from the start is usually the best investment you can make.

For More Details Talk to Gerry or Helen on: 01373 826578 or sales@simpsons1979.co.uk