[3dfernando]

A stream of water can be made with particle flow/spray particles (if you don't know how to use particle flow)
I think you are a bit late, because you will discover that it's a lot of render time for raytraced particles... But if you want to get a good water...

Water is basically transparent, 75% refractive and 50% reflexive (we're talking about pure water)... These are the configurations you should use (well, I do use it =p) with your raytraced material. Remember that a reflexive/refractive material need an environment to reflect/refract, and if you haven't got one, you should fill the "environment" slot of your material with an HDRI map.

Then to make a flow, you need to set up a particle emitter: super spray may work, but if you want to get more flexibility, use particle flow. I recommend you to look for a tutorial with google, because I need images to get further explanation.

Good luck with it =P