Originally Posted by Bama Rambler
Take the Y off back to the valves (and the valves if you want to replace them) and leave the hubs on the holding tank side in place. Unless of course the flange is broken on the holding tank side. Then you'll have to do a little plumbing and you'll need a coupling for the repair.
My problem was freezing.
The lowest part of the gray water system is the fragile ABS plumbing from the tank to the valve. We had put just a few glasses of water in the sink and it wound up in the low part. Two segments of pipe split lengthwise. I had to replace two elbows, three pipe segments, and the hub that goes on the upstream side of the valve. It wasn't expensive at all.
The tricky part was the hub. They come in both male and female, and the illustrations here
are so murky you can't tell which is the male and which is the female. (HINT: Spigot is male; Hub is female). Once you get the part number, you can order from Amazon.
Unlike PVC pipe, ABS pipe and fittings slip completely together when dry (like copper pipe). This means you can cut all the pieces and dry-fit them, then cement them together.
The larger "A" Lowe's stores have a pretty good range of ABS fittings. The smaller "B" and "C" stores do not. Amazon also has a wide range at reasonable prices.