How to Get Rid of a Greenish-Blue Stain in a Porcelain Tub

Cleaning a bathtub can be a formidable task at the best of times and even more so when your tub has developed some tricky stains. A greenish-blue stain in a bathtub, which is typically caused by acidic or low-pH water, needs some heavy-duty scrubbing action and abrasive cleansers. These can be commercial cleaners or DIY versions prepared from common household products. If your stained bathtub is porcelain, the good news is that it's sturdy enough to withstand such aggressive cleaning without risk of scratches or other damage.

Abrasive cleaning products are necessary to scrub away a blue stain in a tub. If you prefer to use commercial cleaning products, opt for a powder-type abrasive cleaner. Mix this type of cleaner into a paste with plain water before applying it to the stains. Alternatively, look for an abrasive, cream-type all-purpose cleaner or bathroom cleaner.

If you want to take a DIY approach, which can be just as effective as using store-bought cleaners, prepare a similar abrasive cleaning paste using your choice of household products:

• Two parts baking soda to one part hydrogen peroxide
  
  
• White vinegar and baking soda
  
  
• Salt dissolved into warm white vinegar, approximately 1 tablespoon of salt per cup of vinegar
  
  
• White vinegar and cream of tartar
  
  
• Baking soda and warm water

Do not use abrasive cleaning products or tools on an acrylic bathtub, which is not as hard-wearing as porcelain. Make sure you know what type of bathtub you have before tackling these kinds of tough stains.

After completing your regular bathtub cleaning, tackle any remaining blue stains in the tub with your choice of abrasive cleansing powder. Wear protective gloves and open windows for ventilation. Apply the product liberally over the stained areas and let it sit for at least 10 minutes. Then, scrub the stains with a melamine sponge, also known as an eraser sponge, soaked with warm water. You could also use another type of abrasive sponge, scrubber, microfiber cloth or scrubbing brush of your choice.

Rinse off the cleaning product with plain water. If the blue stains on the tub remain, repeat the process. Consider switching to a different cleanser or scrubbing tool if your first choice is ineffective.

A good way to prevent more blue stains on the bathtub in the future is to remove all sitting water with a spare towel or squeegee after every use. Another way to keep the bathtub clean and prevent stains is to use a DIY shower spray of one part white vinegar to three parts water. Keep this in a spray bottle on the side of the tub and spray it over all the surfaces after you use the bath.

Tackling blue stains as soon as you notice them is important to prevent their buildup as well. Leaving blue stains to build up makes them harder to clean away, and eventually, they can become impossible to remove. Left untreated, these types of stains might cause permanent damage to a porcelain bathtub as well.

Greenish-blue stains on a tub are typically caused by acidic or low-pH water. They can be an indication that your water is corroding copper pipes and other plumbing fixtures, which can become a problem and lead to costly repairs. If you have an ongoing problem with blue stains in the tub or elsewhere in the home, consider a professional plumbing inspection. Solutions such as acid neutralization systems might be available to you that will solve the staining issue and prevent potential damage to your home's plumbing system.