Most bathroom sinks have a small hole located near the faucet. Many people wonder if this hole is unnecessary or if it has a specific purpose.

In fact, this small, modest hole, located about one-third of the way up the basin, is a clever feature that demonstrates the thoughtful and foresighted design of the sink’s creator, anticipating possible scenarios.

This small hole is connected to the drainage pipe below. During use, there are many instances when users forget to turn off the faucet (for example, leaving to answer a phone call while waiting for the sink to fill). In such cases, once the water level reaches two-thirds of the sink, it will drain through the hole into the pipe, preventing water from overflowing onto the floor and flooding the bathroom.

While beneficial, this overflow hole can also cause users some inconvenience. Since it is located in a somewhat awkward spot, it can easily accumulate bacteria and mold, leading to unpleasant odors rising from the pipes.