Final answer:
An effective solution for cleaning hard water residue from glasses includes cleaning agents with acid, like vinegar, or chemicals with water softening properties such as sodium triphosphate,
Step-by-step explanation:
The best cleaning solution for removing hard water residue from drinking glasses is one that includes water softeners and acidic components like vinegar. Since hard water contains minerals like calcium and magnesium, it's important to use a cleaner that can bind and remove these ions. Acidic solutions like vinegar can effectively dissolve mineral deposits. However, for everyday cleaning, a combination of an alkaline detergent and a water-miscible solvent such as isopropyl alcohol can also be effective.
This combination can be found in many glass cleaners, which are applied directly or with a soft cloth and removed with a lint-free duster. For better efficiency, adding some vinegar to soft water used for rinsing the glasses can prevent residue from forming. Lastly, a synthetic water softener like sodium triphosphate in all-purpose cleaners can enhance the cleaning power in hard water environments by binding calcium and magnesium ions, thus preventing hard water scale deposits from forming on glass surfaces.