Even though manufacturers emphasise the low water consumption of pressure washers in ecological and economic terms, there is another decisive parameter. In contrast to the water hose on the public supply line, the device consumes electricity, which puts the water savings into perspective.
Effectiveness only in relation
The water consumption of a pressure washer is not only a cost factor, but the decisive technical criterion for effectiveness and efficiency. The impact pressure of the high-pressure cleaner of 100 to 200 bar must be put into relation with the amount of water.
Also of interest: How many Bar do I need for my Pressure Washer?
If the water pressure is too low, a lot of pressure is lost through the atomising and non-impacting water jet. The less concentrated the pressure is used, the more pressure force is lost. The relationship between water volume and pressure is not linear. The more water flows in, the less hydraulic or technical pressure the high-pressure cleaner needs.
- 180 bar set pressure and 700 litres of water per hour = 0.6 bar working pressure
- 180 bar set pressure and 1200 litres of water per hour = 1.2 bar working pressure
Example calculation for surface cleaning
A garden hose delivers water at a line pressure of two and four bar. With a pressure washer, the drive energy (electricity consumption) must be included in the cost calculation. The following consumption values can be compared for one hour:
- A water hose with four bar needs about 3,500 litres of water per hour.
- A pressure washer with 145 bar needs about 500 litres of water and 2,000 watts (2 kW) per hour.
The average cost of water in United Kingdom is about two pound cents (0.02 £) per litre. The average cost of electricity in United Kingdom per kW/h is about thirty pound cents (0.30 £).
- Using a water hose costs about 3,500 x 0.2 £, which is equivalent to seven pounds
- With the high-pressure cleaner there are about 500 x 0.2, which corresponds to one pound
and 2,000 kW/h electricity consumption, which equals six pounds.
The decisive savings factor is the time spent on cleaning. If the desired cleanliness is achieved after twenty minutes with the pressure washer, a cost saving of two-thirds (4.33 pounds) can be booked.