About this Blog
MAPEI Tech Talk is a blog devoted to the flooring and construction industry. It is updated on a regular basis by the social media team at MAPEI Americas, and it will feature guest bloggers occasionally as we provide you with viewpoints from across the industry.
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Nick joined MAPEI in 2012 as the technical expert for the UltraCare™ line. He has more than 25 years of experience in the sealers and cleaners product line.
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January 7, 2019 - 16.36
Blue Stains on Tile
by Nick Valenti
Blue pipe
Are the tiles in your shower, or perhaps the shower head or faucets, turning blue? What causes this discoloration and where does it come from? In most cases, it is caused by the water flowing through your pipes having a low (acidic) pH. Chances are your water pipes are made of copper and the blue discoloration is the result of the insides of the pipes being attacked by the aggressive low pH water.

To better understand, pH is the measure of acidity in water. Below is the pH scale which ranges from 0 to 14, with 7 being absolute neutral. Any measurement below 7 is acidic, any measurement above 7 is alkaline. If the pH of your water is 6.8, it is considered “aggressive” and can damage metal pipes, faucets and fixtures. Blue stains begin to appear when the pH of the water is 6.8. To further add insult to injury, each 0.10 of a point is exponentially more aggressive than the number before it.
For instance, if your water tests show a pH of 6.5, you may not be too alarmed because it’s only a few points away from 6.8. Right? Unfortunately, this is a big mistake. Water with a measured pH of 6.5 can cause considerable damage over time, eventually causing serious problems with metal plumbing in your home, and other household appliances, like water heaters, dish washers and ice makers. Although acidic pH water is the most common cause of blue tiles, the opposite effect, or too much alkalinity, can also have damaging effects, such as clogged pipes and fixtures, or slow running faucets. It is important to have the pH of the water coming into your household tested. Simple water test kits can be purchased at most hardware stores or online. Blue stains can be removed but will only return, unless the source cause is determined and repaired.
Remove these blue stains using MAPEI UltraCare Heavy Duty Stone, Tile & Grout Cleaner mixed with equal parts water. Apply the solution to the affected area and allow it to stand for 5-10 minutes. Apply UltraCare Abrasive Surface Cleaner directly onto the same area and scrub using a white scrub pad. Rinse with clean water and dry with a clean towel.
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