Toilets, Sinks, Showers, Tubs and Disposals - Remodeling Basement Bathroom

I have a finished basement that has had some moisture problems in the past, so while I have the sheetrock out and have easy access to piping and electrical I have decided to remodel the bath, among other things like upgrading my copper pipe to CPVC. We have had a problem with the septic backing up through the shower stall drain (which doesn't seal all to well to the pan, hence my "moisture" problem) when we have prolonged hard rains. So I have decided to replace the stall (36x36) with a shower/tub enclosure. My idea is that if there was any further backup through the drain that the deeper tub would be able to contain it better than the shower which only has a three inch lip and leaks around the drain.

The one drawback to that is that the septic backs up into the toilet as well, choosing the path of least resistance. I thought about trying to install a ball valve at the floor flange to isolate it from the drain, but am not 100% sure it is a good idea. Anyone have any ideas concerning this?, is it possible to do it?, and are there any valves designed with this purpose in mind?

I would have backflow prevention installed in the septic line, but there is a substantial (20' x 30') attached deck built over the tank location (this is OK per our local code, as long as the tanks can be pumped).

I'd sure look at backwater valves. Totally different than backflow valve, so do not confuse them. Use these on the drains in the basement.

I don't know about the upgrade from copper to cpvc. I'm kinda a copper guy and don't like plastic for water supply.

Forget the ball valve idea all together. At some point someone will forget to open it to take a shower.

Remodelling your bathroom with new plumbing to deal with backflow seems a lot more fuss and expense to me than just going through the deck - even if you have a fibreglass deck it will be less work I think. Then you can get to the source of the problem.

Or if you must accommodate (i.e. live with) septic backflow, maybe better keep it below the traps by raising the shower and toilet, rather than put in a tub to... yuck. Can you guess the level it'll climb to during heavy rains? Still have showering headroom above that?

I'll second notuboo's opinion of the CPVC. Upgrade from metal to plastic? CPVC is a cost-cutting downgrade I'd only use cynically in a big job after getting the contract. At the scale you're working, you can afford to overbuild a little.

The purpose of the remodeling is not so much to deal with the plumbing as it is to replace the old leaky shower. Raising it is not an option due to the fixed ceiling height (currently 92 ") and I am rather tall (6'4"). I guess I could conceivably raise the toilet. That should not be a problem, in fact I have considered it.

I'd like some more information on the backwater valves, do they install in existing drains, or will I need to break up the concrete slab around the drains to install them?

I wasn't too crazy about the ball valve idea, but was just looking for a solution.

The reason that I am looking at CPVC for the piping is that my water is quite acid (pH of 5.7), and I am concerned that it is wasting the copper piping (I am seeing green stains in the basement fixtures, but nowhere else in the house). I am not thrilled with the idea that one day I will have a pin hole leak or worse a rupture behind a wall or in the basement ceiling, and have to rip it all out again to fix it.

Given my water condition, what would be a viable piping alternative?

Thanks to both of you for the information. I am not a pro by any stretch of the imagination, but I am not a novice either. I have over 20 yrs of Navy experience (retired as a Senior Chief Machinist Mate), so I have done my share of piping changes, valve installs, and pump rebuilds.

Okay, now you gave us sound reasoning for the "upgrade". You should be concerned with the copper pipes and low pH. Look at pex also before you decide on a plastic pipe. You can rent the tools for crimping pex fittings which make it more difficult than CPVC, but the cost and durability is a good option.

A backwater valve is like a check valve installed on the drain line leaving the building. It must be accessable for maintenance as it does need cleaning from time to time. There are little float balls that screw into floor drains to stop water from backing up, but for larger lines, you are looking at backwater valves.

Another option, and this would be work, would be to just install a pump in the basement, drain the toilet and shower to that. Seal off the existing basement drains and have the pump discharge at the level of the ceiling. End result would be the basement can not be flooded from a backup. This would be a very pricey and hard work fix, but it would solve your problem.

Good luck with your project and I am sure others will chime in with more info and options....