Once in a while, people accidentally forget to turn off a water faucet (e.g. a bathroom or kitchen faucet) and leave it running all day.
This wastes water, and is unacceptable.
There are existing solutions to automatically turn off faucets, but generally they are either incredibly annoying (the motion-activated faucets that work approximately 50% of the time) or require some powered / electrical component, which makes them unsuitable for normal home installation.
Since we want to avoid mixing electricity and water (and avoid having to call an electrician for this simple home improvement), the proposal is as follows:
- 1. A standard sink faucet that operates as normal under most circumstances, except for:
- It has a tiny waterwheel in the path of the flowing water that (very, very, slowly) winds up a spring. (Note that we are siphoning off an incredibly small amount of water pressure here, to power the water wheel.)
- Once the spring has been sufficiently wound up (over a period of, say, 5 minutes), it triggers and applies a force the to the faucet handle, causing the tap to close, as illustrated in Figure 1.
This automatic-tap-closing solution requires no electrical components and has very few moving parts.
Additionally, if the spring mechanism does fail, it will cause the tap to simply revert to being a normal tap, rather than negatively impacting the use of the faucet.
In the rare instance when the user does want to leave a tap running indefinitely for some reason, there could be a special lever that disconnects the waterwheel from the spring, letting the faucet run indefinitely.
The actual implementation of the waterwheel and spring is left as an exercise to the reader.
PROS: Saves water, maybe?
CONS: May be excessively mechanically complex for a situation that only occurs about 0.01% of the time someone turns on a tap.