This is an excellent idea that would substantially reduce fresh water consumption on a global scale, which is becoming a major ecological concern. Actually, there have been a number of concepts developed that allow recycling of "grey water" in a home for certain purposes, such as doing laundry, watering the lawn, flushing toilets, etc. They require separate plumbing systems that, of course, are completly separate from sewage plumbing. Grey water recycling systems have filtering, storage and pumping equipment and include a purification device so the grey water system doesn't become a health hazard.

There have been two "problems" associated with commercial installation of these systems. Firstly, they doesn't meet existing building codes and public health regulations, which architects and engineers will tell you is a huge legal hassle. Secondly, they're expensive compared to just using city water and throwing it away. However, I believe that as water shortages continue to grow around the world, we'll start to see more forward looking communities approving, even demanding, domestic water recycling concepts for new construction. However, retrofitting such systems into existing homes, while possible, will be expensive.

I agree, last thing I need while trying to relax is feeling guilty.

Even if the water went into a tank and was used to flush the toilet, it would be a great savings. Maybe someone will invent a holding tank under the shower/tub that can be used with a switching device when the shower water is used up you can still flush from the city water.

Kohler has such a product. Its bodyjet spa both recycles the water and heats it. It is a bit pricey and the main reason for doing this is to increase the water pressure.

You could also "recycle" the heat of the water, by letting the used hot water go through a circuit that heats the house. Alternatively the outgoing hot water could be usedto heat the incoming hot water via a heat exchanger.

I saw this toilet in a magazine some years ago. It has a tank that filled with the water from the shower. Now, I was searching that photo on the Internet and I found this site... maybe if we all search we will find it.

I thought of the same thing years ago. I figured that the ultimate way to do it would be to connect a jacuzzi pump input to the drain just below the tub and have the output connect into the pipe to the shower. You could shut the drain (this assumes that you have a built in tub plug down below the tub) and put a few gallons of water in the tub. You turn on the pump and presto, the water recirculates! Most jacuzzi pumps also have a heater, so it would even keep the water hot.

As a simpler system, you could get a sump pump (available at any hardware store) and simply set it in the tub. You shut the drain and put a few gallons of hot water in the tub. Then, you connect the output of the pump to the lower faucet in the tub (that is, the one you use to just fill the tub). When you turn on the pump, the water in the tub will go up into the lower faucet and come out the showerhead. This won't be as nice looking as the other system, but it wouldn't require major alteration to the plumbing (though you may have to alter the lower faucet in order to connect to it).

i have pondered this idea while taking long showers as well, it would be nice after the first few minutes when one is clean, to be able to switch from the standard piping to a recycling system. also, this saves the cost of heating more water, as the water you are recycling is already at the desired temperature, or if it has cooled slightly, perhaps you could have an adjustable in-line heater, or simply have that water mixed with small amounts of water from the standard hot line. i think it is an excellent idea,

I have thought about something like this over and over again in my head for years. I have always told my wife that when we are rich and get our own place (renting now...), we would incorporate a system exactly as you are describing and for the exact same reasons as you are describing.

One important component to take into consideration in the energy budget would be the heating load. Maybe solar would be a good option... It is an interesting problem that I will certainly look at someday! Thanks for bringing it up.