You will never know the answer. I searched but didn't see any post about the ones in the water works bay. I have been using the low point drains to empty all the water out when needed and have never really noticed the cutoff valves in the water works bay. I opened one up and noticed clean water rushing out. My question is, what are these valves for? Are they a second set of low point drain for the front bathroom? The second set, the ones I have always used are under the rear bathroom? Again, if you don't ask a stupid question you will never know...lol I have enclosed pics for reference. Thanks,
Glenn
Inside water works bay
Underneath bay
Fresh water low point drain
Rear hot cold low point drain