automatic water saving toilet
 

Has anyone thought about designing a mechanism for a toilet that varies the amount of water used when flushing depending on whether the seat is up or down? I'm thinking of a purely mechanical system that uses a strong magnet attached to the bottom of the seat to activate a mechanism inside the tank.

Seat up vs. seat down savings would only apply to men, I believe.

Interesting idea Mike! I'd have to agree with Piwoslaw though. The dual flush retrofits aren't that expensive and might even be fairly doable as a DIY if you look a little closer at the systems if you wanted to save the ~$50.

having two flush buttons is to hard? I live with two females so a toilet like that wouldn't work for them and we all close the lid (not just the seat) when we are done, so what would happen then?

even on a city lot I pee out side if you I, being on the upper leavle of the house makes it harder and that the yard has no privacy until after dark is the biggest challenge.

What about have some way to sense weight on the seat? Maybe have the tank fill only partially until there is a significant weight (say, over 25lbs or so) on the seat, at which point the tank continues to fill. It can be designed so the weight of the lid is not enough to activate it. (One drawback is that it might surprise someone who is not expecting it.)

Or what about a solenoid connected to the exhaust fan that activates the mechanism?

I have a holding tank at my house for wastewater, so I DO pay plenty of attention to how much water gets used.

My toilet simply has the chain from the flap to the handle adjusted so that the flap only stays open as long as you hold the handle.

Simply press down the handle briefly for a small flush, and longer for a bigger flush!

I believe this method of producing a #2 sized flush is still flawed in the case of the fairer sex.

Easy,
forget about replacing the toilet with a new (stupid) dual flush system.

Replace the chain from the flush handle to the ball ****, with a rod.

You now have the ability to lift UP on the handle to limit the flush cycle
to any thing you desire.

Also helps greatly to aleviate stress when there is a "backup"
as you can stop the flow right now.

You're right - the noise would startle them. Easy workaround is to add an "EcoFlush" label to briefly describe the operation of the mechanism. Or slow down the water flow to keep it quiet.
Good idea, and it can be combined with some other ideas. Those unaware of this feature will not use it, however. My idea works completely automatically.

If you're using a pump to fill the toilet, it's even easier to integrate the controls. Replace the existing fill valve with a piece of pipe to just above the water level (cheaper, more reliable, and less pressure drop than a check valve) and add some sort of sensor to sense the water level. Then add a weight sensor to sense weight. (Or maybe a switch that activates only when the seat is down and the lid is up?) Design the controller to only fill to a low level until the weight sensor is activated, at which point the pump starts back up to continue filling. In addition to saving a rather limited supply of used water, it also saves energy used to pump the water. (Proper circuit design can ensure the controller standby losses are negligible.)

"(Proper circuit design can ensure the controller standby losses are negligible.) "

Controls ?

And when the electricity goes out ?

Repeat after me....A toilet should not have a P.L.C. on it,
nor electricity wired to it.

"Those unaware of this feature will not use it"

A simple label should work well. Something like
"lift handle to stop water flow"