Hard water stains are caused by a build up of minerals and make surfaces look dirty and unpleasant. Granite countertops are particularly susceptible to hard water stains but fortunately, a little 'elbow grease,' chemical assistance and knowledge of the correct procedures can remove hard water stains from granite countertops relatively easily.
Step One - Protect Yourself
Before you attempt to remove hard water stains from your granite counter tops, put on protective gloves. Whether you decide to use the wire wool cleaning method or a heavy duty cleaner, always wear gloves to protect your hands from potential damage. Muriatic acid is recommended to be used as a last resort to remove really tough hard water stains. If you do use this product, always wear a safety mask to ensure you do not breath in the toxic fumes.
Step Two - Scrape the Stain away
Preferable to using chemicals, the ideal way to remove hard water stains from granite countertops is to scrape them away. Using wire wool is an effective tool for eradicating hard water stains from various surfaces in the kitchen and bathroom. Using wire wool is particularly beneficial when used on granite countertops, as it will not damage the surface. Dip the wire wool into some soapy water and carefully rub at the stain until it is finally removed from the surface. Instead of wire wool, a razor blade can be used to scrape away hard water stains. Make sure you are wearing protective gloves and slowly chip away at the stain with the razor blade.
Step Three - Apply a Stone or Granite Cleaner
If the wire wool or razor blades are unable to remove the hard water stains, you will need to purchase an alkaline or low acid heavy duty cleaner designed for use on a granite or stone surface. Apply the cleaner to a dry, clean brush, sponge or rag and rub the stain in a circular motion.
As different brands offer different application advice, it is important that you read the instructions provided with the granite cleaning product you have purchased. Leave the cleanser penetrating into the hard water stain for the amount of time advised on the instructions, allowing enough time for the chemical reaction to occur before wiping off with a cloth. The hard water stain should have disappeared. Exercise caution if you are tempted to use a hard water and mineral remover, as most of these products advise that they are not to be used on natural stone surfaces.
Step Four - Use Muriatic Acid
If commercial stone and granite cleaners or hard water and mineral removers are not removing the stains, purchase muriatic acid. This is a weak form of hydrochloric acid and can be applied to the stain. Since muriatic acid is toxic, be sure to wear protective gloves and a protective mask so that you do not inhale the fumes. Wash your granite countertop thoroughly before you apply the muriatic acid, as it may react erratically if it comes into contact with other household cleaners.
Blot the acid onto the stain with a rag. Leave it for 20 seconds and quickly remove it, using plenty of water to flush any traces away. All traces of the hard water stains should have been flushed away as well.