Remember this guy?
It was pretty cool what he did. The only problem was what he did looked like shit, and more importantly, he was being an asshole about it, refusing to tell anyone how he did it.
So I decided to do it right and do it myself.
It's very easy to do what he did, and I did it 10x better. I'm at work right now so i can't give specifics, but all it involves is a collision controller in the particle system.
The only problem is i can't think of what to do with it gameplay-wise. You can't detect particles in a volume so you can't do anything like filling up buckets :(
Here's a download link if you want to play around with it.
If you do it in GMod you don't need the particle_manifest.txt file. Also if you're going to mess with it in GMod you'll probably want this:
You'll have to type the name of the system manually into the tool. Its name is "water_faucet".