When it comes to getting hard water stains off of clear glass, there are a few different methods that you can use. One popular method is to use a vinegar and water solution. Simply mix equal parts vinegar and water together in a bowl and then use a clean cloth to wipe the solution onto the glass. Let it sit for a few minutes and then use a second clean cloth to wipe it away. You may need to repeat this process a few times to get the best results. Another method that you can use is to make a paste out of baking soda and water. Again, mix these two ingredients together in a bowl until you have a paste-like consistency. Rub the paste onto the glass using a clean cloth and let it sit for a few minutes. Once the time is up, use a second clean cloth to wipe the paste away. You may need to repeat this process a few times as well. If you have any stubborn hard water stains that just won't seem to come off, you can try using a glass cleaner that contains ammonia. Simply spray the cleaner onto the glass and then use a clean cloth to wipe it away. Be sure to open a window or door to ventilate the area while you are using this cleaner, as the ammonia fumes can be quite strong. Hopefully one of these methods will work for you and you'll be able to get those hard water stains off of your clear glass.