[SnaggyJoker]

If they used less hot water they would use less energy heating the water.

That was the original thought until I went off on the tangent about saving the hot water in a separate tank from the bathtub after it is "used" for the bath allowing the heat to be harvested and the water to be re-used.

The original post is about leaving the hot water in the bath to use the energy to heat the house or help heat incoming water. The idea of an external tank made out of conductive material would eliminate some of the problems and also allow the water to be re-used for the toilet.

[anigbrowl]

I see your point but I am not sure about this. I suspect a lot of people use just as much water but spread it out longer. In California there are a lot of devices mandated to reduce consumer use (flow restrictors and so on), but interior water use often demands fixed quantities. For example if you want to have a bath rather than a shower then people will use the capacity of the tub, likewise if you boil water for cooking a flow restrictor just means it takes longer to fill the pot to the required level. So people use just as much but just suffer lower pressure.

Toilet cisterns arguably do reduce usage but then many people complain about less effective flushing which requires additional water; I don't have data to know if these objections are just a cliche or reflect an actual problem. My understanding is that lawn-watering is the biggest waste of water by consumers, to the point that some local authorities will subsidize people reorganizing their gardens to be more suitable for a dry climate.

[Baeocystin]

What California really needs to do is ban alfalfa farming for export. It is infuriating how much water goes to that crop alone for absolutely trivial amounts of return, compared to what the water consumed could have been used for. Water rights in the American West are an absolute cluster.

[briHass]

As for the issues flushing large, ahem, amounts of waste with the low-water toilets, it's mostly just cliche now. When the restrictions were first added, the toilet manufacturers weren't ready. Probably a lot of the complaints were from experiences with these early models.

Now, low-flow toilets have an amazing amount of research and design put into how to meet the guidelines while still performing as well as, and often better than, old 4+ gallon flushes.

A few (ill-informed) complainers aside, this actually seems like a win all around. Toilets don't cost more than they used to, they use less water, and perform better than ever.