Traditional Culture Encyclopedia - Hotel accommodation - Why did the washbasin of the hotel get dirty for no reason the next day?

Why did the washbasin of the hotel get dirty for no reason the next day?

Impurities in tap water. Hotels generally use tap water as water source. There are many impurities in tap water, among which metal ions precipitate on it, which will lead to yellowing, resulting in scale and stains, which is why the washbasin of the hotel will be dirty for no reason the next day.