A successful trip to a public bathroom includes using your hands as little as possible, so motion sensors should be a welcome feature. The technology is meant to offer convenience and cleanliness, but it’s instead become associated with stingy air dryers, phantom flushes, and faucets that won’t respond to anything less than 30 seconds of intense flailing.  

To know what’s happening when these sensors fail, it’s important to understand how they’re meant to work in the first place. Products can vary, but the majority of bathroom sensors rely on infrared technology. When a toilet isn’t being used, the sensor emits a continuous beam that covers the area of the toilet seat. When a user sits down, it switches to “hold mode” and waits to flush until the immediate space has been vacated. Some models adjust their flushing strength depending on how long the user was there (so you can add “how much time you spend on the toilet” to the growing list of things you can’t hide from robots).

If the automatic flush fails to activate, it’s likely because the sensor hasn’t been cleaned properly. Hard water can cause calcium and lime build-up, which is the most common source of performance issues. Sometimes the problem can be explained by people sitting too far away from the sensors or peeing while standing up. Dead batteries could also be the culprit. 

These are the results when the technology fails, but it can be even more frustrating when the motion sensors function exactly the way they were intended. To speed up traffic flow in busy bathrooms, owners will dictate how long their faucets and air dryers run. If you’ve noticed speedier bathroom appliances in stadiums and casinos, that’s not in your head. The allotted time per use is optimized to account for heavy foot traffic, making sure users get in and out quickly no matter how wet and soapy their hands are.

Because this technology can be easily regulated to suit the owners’ preferences, it’s extremely popular with prison markets. Prisons have become something of a testing ground for bathroom sensor innovation, with technology like remote controlled bathrooms already becoming well-established there before taking off in the commercial sphere. If a future high-functioning, micro-managed public bathroom waits on the horizon, you'll have the prison system to thank. 

[h/t: Vox]