In this guide, I focus on using a plastic cleaner/polish called Meguiar’s PlastX. This product is generally used to polish plastics, but I’ve found it to be useful for mild hard water spots on glass that can’t be removed chemically. The level of abrasion with this formula is quite mild, so it has negligible effect on the clarity of the glass. You don’t even need to use a machine polisher, you can actually do all of this by hand with either a microfiber towel or a microfiber applicator pad (preferred). If you have a considerable amount of glass that needs water spot removal, then you might consider using a machine polisher, although you can still do it by hand; you just need a bit it of elbow grease.