How do I get a hardware idea made? (by someone else..)
vabmit: There is a start-up here in Cambridge, MA that was founded by a couple of MIT Grad Students called Course Zero Automation:http://www.coursezero.com/I've talked with them about their rates for working on physical device start-ups with me before.  And, they were very reasonable.  I know both of the founders and they're highly skilled and highly competent.  They initially founded the company to compete on the DARPA prizes related to military device needs (specifically non-GPS navigation).I'd highly recommend them if you're looking for engineers to do the consulting work necessary to develop a device like this.Also, I like your idea.  Green is big right now, and this is both an energy savings and water savings play.  If you developed the device in a way that allowed it to shut off water flow after a given amount of time, you may be able to market it to large government markets such as federal and state prisons and the US military.  One of the military challenges presented to MIT students this year was for a device capable of cleaning and disinfecting clothing with a very limited amount of water.  In current battle field theaters, the US Military is really struggling with the logistics of troop water supply.