That Crusty Bathroom Scum Is Actually a Buildup of Lime

Special to The Times

That crusty scum around your faucets seems impenetrable. You’ve tried scrubbing, but it just won’t come off. What is it? How can you remove it?

These household nuisances are buildups of lime, actually calcium oxide, which occurs in the earth’s surface and is carried to your sink and tub through the water supply. It builds up on itself, forming a crust, when water puddles and dries around faucets and drain lips.

Lime can be removed by applying an acid-based cleaning product. The acid is phosphoric, in most cases, but may be even stronger in some products, such as hydroxyacetic acid found in the product Lime-A-Way.


Whatever cleaner you use, apply the product, let it sit, loosen the lime with a stiff brush or abrasive pad. Be careful not to scratch your faucet or porcelain--only rub the caked on lime. Reapply as necessary, rinsing well between applications. For extremely heavy buildup, scraping or chipping with a blunt tool such as a butter knife may be necessary after the buildup is somewhat loosened.

Do not use these acid-based products in combination with ammonia or bleach or their derivative products, as toxic fumes will result. Read and follow label directions.