White vinegar is one of the the best eco-friendly cleaners for removing water marks particularly if a bit entrenched. Mix white vinegar with water (50:50) and use it as a cleaner to remove the water spots on your glass shower screens. Dip a microfiber cloth into the vinegar cleaning solution and wipe the glass surfaces. Some scrubbing may be required if the water spots have been allowed to accumulate for a while. After cleaning, use another microfiber to dry it and bring out the shine on your glass shower doors.
If you prefer not to have any vinegar smell in your bathroom, another alternative is to use the plain old lemon juice. Just cut a lemon half and scrub the door with the lemon. Rinse with water and dry it with a microfiber cloth.
The key to keeping your glass shower doors clean and shining is to maintain it regularly. Don’t allow the mineral deposits in the water to build up on the glass surfaces. To prevent this, keep the surfaces dry after you shower. Keep a rubber squeegee in the bathroom and use it to quickly remove the majority of the water residue. This will keep the watermarks down to a bare minimum.