A few years ago we had our master bathroom re-floored. I took this opportunity to have two water lines brought through the floor for the toilet. One of them is normally connected to the house plumbing. The second is connected to a rain barrel outside. I can easily change which line is connected to the toilet in times when the rain barrel has run out of rain.

The line runs from the barrel into the crawlspace beneath the house and into a 12V RV water pump. The pump is powered by two old car batteries.

Does this save any real amount of money? Probably not. There’s just something satisfying about flushing freely available rain instead of drinking water.