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Tag: faucet

With this enhanced hand-washing sink timer, you may reduce your chance of contracting a deadly plague!


It is well known that washing hands for a surprisingly long time (30 seconds!) substantially reduces microbial contamination (Figure W1).



Figure W1. Image contributed to Wikipedia by user Pöllö, for article “https://en.wikipedia.org/wiki/Hand_washing“: “Microbial growth on a blood agar plate without any procedure (sector A), after washing hands (sector B), and after disinfecting hands with alcohol (sector C).” Source

The issue:

Unfortunately, people generally feel, psychologically speaking, that their hands are clean immediately upon rinsing them with even the slightest hint of water.

The challenge, therefore, is to encourage people to wash their hands for the recommended 30-ish seconds.

Although hand washing timers already exist, these are not sufficient—they don’t enforce the washing time.


To improve on the existing “hand washing timer” product, we will enhance the sink’s faucet with a “wash hands” button (Figure 2) that can control the faucet to perform pre-programmed behavior.


Fig. 2: A regular sink (left), and a modified sink with a “wash hands” button (right). A user who wants to, say, fill a water bottle, would use the sink normally. But a user who just wanted to wash their hands would press the wash button instead of interacting with the faucet handle.

When the wash button is pressed, the tap performs the following actions (shown in timeline form in Figure 3):

  1. The tap turns on for ~5 seconds, allowing the user to get their hands wet.
  2. The tap turns down to a trickle for 20 seconds (allowing the user to wash their hands, but not providing enough water to wash off the soap)
  3. Finally, the tap turns on again, allowing the user to wash the soap off their hands.

Fig. 3: Here, we see the timeline of water flow (Y-axis: flow rate. X-axis: time since the button was pressed). The interval lengths could be adjusted as desired.

Bonus fact:

Apparently water temperature doesn’t make a difference: “Contrary to popular belief however, scientific studies have shown that using warm water has no effect on reducing the microbial load on hands” (from https://en.wikipedia.org/wiki/Hand_washing). You can fact check that one yourself, if you want!

PROS: May reduce the spread of deadly deadly.

CONS: Could increase the rate of dry hands; this discomfort must be weighed against the severity of any to-be-prevented plagues.

Stop wasting water: with this new incredible invention, you won’t have to worry about leaving a water faucet running again!

The issue:

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. 1. A standard sink faucet that operates as normal under most circumstances, except for:
  2. 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.)
  3. 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.




Fig. 1: This automatically-turning-off water faucet is entirely mechanical, and has no electrical components to fail and/or electrocute the user. The waterwheel and spring/gear mechanism (not shown) would go in the path of the water flow.


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.