How do you remove blue stains on your fiberglass shower and what causes them?

The most common causes of blue staining on fiberglass bathroom fixtures depend on your source of household water. If you are on a municipal water supply, the stains will likely be limited to areas where the water drips, such as beneath the jets in a toilet bowl, or around the faucets and drains of the sink and tub. This is due to chlorine saturation in these spots. Municipalities treat their water with chlorine to disinfect it and keep it that way until it reaches the farthest customer. This chemical, when applied continuously to a particular surface through dripping or leaking, will leave a blue/green stain.

If you have a well that supplies your household water, blue/green staining will almost certainly be due to your water having a low pH factor. This makes the water slightly- to significantly corrosive to soft metals like copper piping. This corrosive action causes the copper to leach into the water, and it is then oxidized as it passes through the aerator in your faucet, depositing a copper oxide stain on the porcelain or fiberglass fixture. Improper grounding of the household electrical system can also cause this leaching, by electrolytic action.

Removal can be accomplished reasonably well and without too much effort using such products as CLR, The Works, or other similar tub/shower cleaners. If you stay on top of it, the cleaning is more like a weekly wipe-down, as these products do most of the work by chemical action. If you have low-pH well water, ask a water professional about getting an acid neutralizer installed to permanently stop the problem.