Would something like this be part of your solution?
http://www.dripdepot.com/drip-irrigation-kits-for-clean-water
It’s not quite what you are looking for but you may be able to adapt some ideas/parts from it.
That picture has a rain barrel. If you wanted to have an indoor rain barrel you could attach a pump to it. That would get you the pressure needed to connect regular valves to.
Craig