Low point drain valves are little valves you will find at the lowest points of your RV. Their function is to make sure all your freshwater lines can be emptied thoroughly for storage, cleaning and to prevent freezing in the lines.
Many install a valve in place of the plug to make it more convenient to use: https://www.amazon.com/Cash-Acme-22222-Push-Fittings-2-Inch/dp/B000KE4NUO
