Most standard 120 volt household outlets can supply a maximum of less than 15 amps. This determines the maximum power that is available and this translates into the maximum horsepower that is available. Most small pressure washers that run on standard household outlets will be a compromise between pressure and volume. If this type of pressure washer can provide for example 1200 PSI it may be capable of delivering 1.8 GPM. If this same type of pressure washer is designed to provide 1600 PSI, it may only be able to deliver 1.4 GPM.

Pressure and volume will trade off to stay within the limits of the power available. If more cleaning performance is required, a pressure washer designed to run on higher voltages and/or higher currents may be necessary.

Another way to obtain higher pressures is with the use of gasoline or diesel engines which are not limited by any electrical power source. This often increases a washer's portability as well.