I decided to put a shower in by my pool to rinse off if needed. After mulling the design over and looking on here I came up with something that may work. I built a 6" dia schd 40 "tank" x 84" long. This is mounted inside a 8" dia steel pipe which is anchored into the ground. The 8" pipe is filled with water to help conduct the heat from the sun shining on the steel pipe to water in the 6" tank. My theory is the water in the 8" pipe will warm in the sun heating the 6" tank, when the shower chain is pulled, cold water will come in at the bottom, mixing and forcing the warmer water out at the top. I think this will give me a minute or two of a warm shower. Even when the water has cooled there will still be a +- 1" layer of hot water surrounding the tank to start rewarming the new water. I'll post some pics later. I still hav'nt recieved the rain showerhead and valve but will have the rest done today.