[jfgvbdvw] Leaving the toilet running

Leave the water running, most commonly to keep the pipes from freezing.  However, we would like to stop the water if the drain should become clogged for any reason (perhaps the drain pipe froze) to prevent a flood.  (Better to take our chances with the uncertain possibility of pipes freezing and bursting, than the certainty of a flood from a clogged drain.)  Need some feedback system that will shut off the water if it is not draining.

A toilet almost works: the tank has a float which measures water level.  However, it doesn't quite work for this purpose because a clogged drain will overflow the bowl.

Create a toilet tank draining directly into the drain.  If the drain fails (clogs) and the feedback system also fails, then it will flood.  A normal toilet has an overflow tube for if the feedback system fails, but it is useless in this case.

One could have multiple failsafes, for example, the tank overflows into another tank which also measures water level and which can also shut off water if this second tank fills up.

The toilet flush and refill mechanisms elegantly do not require electricity, which is always iffy in severe whether anyway.