Water Conservation-Shower Timer

I want to transition to using captured rainwater, and I've considered various means of water conservation, but I know that for me the best option would be a timer that I could set for two minutes, it turns the water off, and then when I'm ready I set it for another two minutes. I searched the internet and all I can find is a thing that lets the shower run for 5 minutes (not adjustable) and then turns itself off for another 5 minutes (also not adjustable). That is definitely not what I want. The YMCA I went to as a kid had a timer that looked like these:
http://www.intermatic.com/Products/Timers/InWallTimers/Springwound_Auto-Off_Timers/FFCommercialSeries.aspx set in the shower wall, but it would only run for three minutes. The linked product is not made for use in showers. Does anyone have an idea of how to rig up something?

No ideas for a shower timer, would a foot operated switch help.?


http://m.instructables.com/id/Cozy-Low-Energy-Shower/

He has other great ideas for saving water in there...

Thanks for the link. It has several good ideas, including those in the comments. I have used the shower heads with the button on/off on the head before and that helps a lot when taking a "Navy shower" to keep the water at the right temperature in between rinses. I'll probably do that again, although even better would be a shower head that requires pressing and holding a button/lever to release the water, rather than pressing to stop it. One other thing I've seen in the past is a heat lamp above the shower, which directs heat only where you need it without having to heat up the whole space. That would be good for the cold days when I don't want to turn off the shower.

Apparently a shower head that you have to hold lever to keep on is only sold in Europe: http://www.everydropisprecious.com/thumb-operated-lever-shower-head.html. There's also something similar called a "Muslim bidet," also only sold in Europe. Perhaps a kitchen sink sprayer or an outdoor hose sprayer could be modified to work. (One too little pressure, one too much??)

The items you are looking for can be purchased from Europe or Japan. The internet is a great tool for items that can't be found in the Americas. My brother regularly buy items from Europe the biggest hassle appears to be the shipping cost. Most companies will ship FedEx or UPS, so customs will be taken care of easier than if you were shipping with other methods.