Keystone RV Forums - View Single Post - Shower and bathroom sink grey water tank.

MarkEHansen · 10-21-2018, 07:35 AM

I'm not aware of any downsides to leaving the gray valve open (others may), but one thing is that you need sufficient gray water to assist in the flush of the black tank through the dump hose. When you're planning to dump the black tank, you'll want to make sure you close the gray valve enough in advance that you have sufficient gray water to aid in this dump/flush.

10-21-2018, 07:35 AM	#3
MarkEHansen Senior Member Join Date: Oct 2018 Location: Sacramento Posts: 1,005	I'm not aware of any downsides to leaving the gray valve open (others may), but one thing is that you need sufficient gray water to assist in the flush of the black tank through the dump hose. When you're planning to dump the black tank, you'll want to make sure you close the gray valve enough in advance that you have sufficient gray water to aid in this dump/flush.