I believe there’s a pretty good preset in Particular that will put you a good way toward water from a hose. Another option if you have a bit of money to spend is Particle Illusion – it has several killer water presets, from waterfalls to hoses:
https://www.wondertouch.com/default.asp
It can be purchased as a plugin for After Effects, or a free-standing package. I would suggest the free-standing package, since it gives you a lot more under the hood control of particle size, color, and hundreds of other parameters. That said, the presets are so good that you might get away with the plugin version – read up on it. It has a very deep set of capabilities, from explosions, to water, to fairy dust, and more…
Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com