Gray water lines: What diameter?

[RJ]

FWIW . here in Mass. 2" is actually required for showerstalls. A bit of an overkill it seems. mike

Mike -

Not if there are several females (or males) in the house with long hair.

Less risk of a plugged line, especially if it's a concrete slab foundation.


Steve -

Metric equivalent, if needed, would be 3.175cm = 1.25",  3.81cm = 1.5",  and 5.08cm = 2".

Whatever you do/use, be sure to get the correct glue, makes a big difference.  Beware, too, that there are "hot", "medium" and "cold" types, which correspond to how quickly they set up.  "Cold" gives you lots of time to work with the glued joint before it sets up, sometimes annoyingly so.  "Hot" sets up extremely quickly - better get it right the first time, or you'll be cutting it out to do over.  Tip: A "Fine Point" Sharpie is a very handy tool when fitting together plumbing before gluing.  Can even be seen on black ABS if work area is well-lit.

Highly recommend, if using ball valves anywhere in your plumbing, to get the models with unions on them - these valves do screw up, and with unions, are easily replaceable.  If you can't find them at a plumbing supply, try a swimming pool supply (wholesale, not retail.)  Buy spare handles at the same time - those are the first to go!

Also, two "45s" together are much less restrictive than straight or street "els", sweep els are even better. Less restriction = better flow.  (One 2" straight/street elbow = 7' of straight pipe in terms of resistance to flow.)

FWIW & HTH. . .

[luvrbus]

RJ,the Fernco couplings work better than unions on drains a screw driver and you are there lol  they are flexible and a lot cheaper to buy

[Brassman]

I agree with luvrbus, Fernco is a good friend for RV drains.

[Dave5Cs]

Fernco couplings are for apprentice plumbers. Real men use glue, LOL

Dave5Cs

[belfert]

Fernco couplings are for apprentice plumbers. Real men use glue, LOL

I don't think anyone is saying to use Fernco couplings exclusively.  (At least I hope not.)  Using a few of them to make it easy to remove a tank for repair isn't a bad idea.  I had to cut my plumbing to remove my tank once.  The only time I have used a Fernco coupling is for the drain line on my sump pump at home so I can remove the pump.  It drips a little as they aren't designed for pressure.

[Dave5Cs]

All seriousness aside, I have actually used them for hooking up sewer lines when the owner didn't want to pay the price to change all the clay line to ABS and we took out a portion of it and the used one between to hook up to ABS and clay pipe. They work well. Also if I were to do the tanks again in the coach I would put on on all the top connections to the tanks just incase I had to remove them. Makes life easy.

Dave5Cs

[RJ]

Clifford (and others) -

I understand your comment about using Fernco couplings, but I you missed what I said:

Highly recommend, if using ball valves anywhere in your plumbing, to get the models with unions on them - these valves do screw up, and with unions, are easily replaceable. 

Completely different application than what you'd use a Fernco for.

Sorry if I didn't make that clear in my original post.

FWIW & HTH. . .