Are high pressure pumps really necessary?

Yes, high pressure pumps allow for the creation of a mist that will evaporate faster, without getting you wet.

HydroMist's misting systems use high pressure pumps (1000 psi) and misting nozzles with very small holes (0.008".) Very small misting holes require the high pressure pumps to expel water as a very fine, fast evaporating, mist or fog.

Low pressure systems are not be able to expel water from very small holes, therefore large holes are necessary in the misting nozzles. The combination of low pressure and large misting holes results in large water droplets, which do not completely evaporate—this can often produce the appearance of "spitting" or “raining” upon people causing them to get wet.

High-pressure systems use less water, compared to low-pressure systems with a similar nozzle count.