My fifth wheel has four low point drains also. One is to drain the hot water lines, one is to drain the cold water lines, one is to drain one of two fresh water tanks, and one is to drain the second of two fresh water tanks (in mine, the tanks are ganged together - that is, if you fill or empty one, you fill or empty the other. Each having its own drain just makes the draining faster. On mine, the two fresh water tank drains are small valves with handles that rotate. The two drains for hot and cold water are push - pull drain valves (you pull up on the valve handle to drain, and push it back to snap it closed.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch