City water coming into my home during January measured about 34.7 F - 2 C. To pre-heat the water for the hot water heater, I decided to use the water going down the shower drain.
Finished the hot water heater plumbing tonight. Have it pressured up. No major leaks so far. I arranged shut offs so I can cut out the Pre-warmer. Tomorrow I'll plumb in the drain water from the shower. When I have time I'll add the drain water from the dish washer.
This is the south facing wall of my home. During the summer I hope to add a Solar water heater to the side of the house And add four barrels to pre heat the water.