How short can a nozzle be made?

For best performance, the minimum nozzle lengths for various nozzle designs are listed below:

Custom stainless and semi-rigid copper nozzles can physically be made down to 2" long. However, going shorter than a 4" nozzle will result in choppy/pulsed fluid output and it will be very difficult to get steady fluid output from the nozzle especially at slower pump cycle rates.