Why Is My Bathroom Sink Yellow in the Bottom?

A major cause of yellow staining in a bathroom sink is hard water, or water with an overabundance of minerals. This source of staining is especially likely if your home uses well water. Since yellowing due to hard water occurs where the stream of water hits the sink, the stains are likely to appear only in the sink bottom. Hard water stains can be difficult to remove once they set in, so prevention is key.

Several solutions may be used to eliminate hard water stains. House Cleaning Central recommends scrubbing hard water stains with a solution of 1 cup of vinegar and 1 tablespoon of lime or lemon juice on sink surfaces other than marble, though another option is to purchase cleaners recommended for hard water stains. Once stains have been removed, prevent hard water stains by ensuring that the faucet in the sink does not drip, cleaning the sink after each use and having a water softener installed in the water lines if the problem persists.

Another common cause of yellow staining in a bathroom sink is the accumulation of oil in the bottom of the sink. Though you may not be using products that you consider to be oils in the bathroom, you likely use several products with oil bases, such as lotions. When you use oil-based bathroom products near the sink and rinse them down the sink without wiping them up, the oils may accumulate at the sink bottom and eventually cause staining.

Yellow oil stains in a bathroom sink may be prevented by using oily products away from the sink to prevent spills. Since that may be inconvenient for many people, however, you can prevent staining in the same way that you prevent hard water stains, through regular cleaning. The Cleaners register recommends orange-based products or heated vinegar for cleaning up foreign substances on bathroom fixtures. You can also be proactive in preventing yellow oil stains by simply cleaning up any spills with a wet rag.