View Full Version : Design Issue: Standard or rear discharge?

Amish Electrician
11-18-2011, 10:46 AM
Folks, as my name suggests, I'm no plumber.

I bought a rather well-worn house, one that needs a complete gut remodel. Plus, the 1957 cast iron sewer is toast.

My remodel will involve relocating every plumbing fixture, as well as shifting some walls. I'll have room for a rather generous chase between the kitchen and the bathroom. The toilet will be relocated about 24", into an area currently occupied by the wall behind the toilet.

Starting with such a 'blank slate,' I have to ask: is there any advantage to choosing a rear-discharge toilet over a bottom-discharge model?

11-18-2011, 11:30 AM
A floor discharge tends to work easier. Anytime the plumbing can go down, it's an advantage.

Gerberit and Toto have an in-wall system for a wall carrier, or the American Standard Glenwall uses the standard wall hung carrier.
I've been toying with the idea of installing the in-wall in my master. Somethiings are just cool. If I do the in-wall, it will be just the bowl hanging on the wall. Thinking, thinking...........


11-18-2011, 02:38 PM
Rear discharge could be a floor mounted or wall-hung. I see no advantage to a floor mount-rear discharge, but a wall hung has some merit...easier to clean and typically, will project into the room less. Keep in mind that you have lots more choices on a traditional toilet, but that may not be an issue.

11-19-2011, 01:19 PM
A floor mount OR a wall mount will have the same projection because both of them fit against the wall. The ONLY advantage to a floor mount is that you MAY NOT have to break into the floor, depending on how the pipes are arranged, butyou do NOT need an expensive wall carrier fitting that a wall hung one needs.

Amish Electrician
11-20-2011, 04:51 AM
Thanks for the replies!

You've hit on my dilemma. I ask in another thread about curbless showers. I'd like to have the entire bath floor (total bathroom will be appx. 8' x 10') act as a shower pan. Eliminating the connection under the toilet would remove that complication. (Piercing the membrane, the floor being sloped there, etc.)

Why bother? Well, I have used such bathrooms and I like them. True, most of them were very small bathrooms- but even the best bathroom gets water on the floor. Whether from wet feet or overflown fixtures, it's really nice if there's a drain for the water to head to.

Returning to the topic of the back-discharge toilet, my decision will depend on two factors: whether I'm inviting clogging problems, and the price / availability of the rear discharge. If I'm required to have access to the drain pipe from the backside of the wall, the idea won't work. I'll have a generous chase -the wall wil be about a foot wide between the drywall faces- it won't be nearly wide enough for a man to enter. With the kitchen counter/ range on the other side of the wall, I might not be able to have an access door there.

11-20-2011, 05:48 AM
I suspect, but do not have data....that they have a little more trouble flushing the wall mount type, whether floor mount, or hung, because they are ONLY made today with pressure assisted flush, or of cours flushometers for a hung toilet. You will not need access inside the wall once properly installed.

Remember, if you put in a main floor drain, you will need a trap primer. Or are you planning to have the only drain be the shower drain?

11-20-2011, 06:22 AM
The floor and wall for a floor mount rear outlet toilet HAVE to be perpendicular to each other, otherwise you will have to shim and caulk the bottom of it so it is level. The floor in a shower room would NOT be level if you want good drainage. The plane of the floor is immaterial with a wall hung toilet, with the added benefit that you can mount the toilet at any height you feel is comfortable. You do NOT need access behind the toilet, and with the proper installation do not even need an overly thick wall.

11-20-2011, 06:46 PM
http://totousa.com/ProductDetail.aspx?productid=729 is a wall-hung, dual-flush version of the Toto Aquia. It projects into the room about 8-9" less than the 'tanked' version (regular bottom discharge). I'm sure there are probably others.

Amish Electrician
11-21-2011, 03:43 PM
Presenting me with actual FACTS, and a practical look ... I'm beginning to really like this forum!

Thanks for setting me straight about there not being any need to access the back side of the wall-mounted toilets. Until now, my only exposure to them was a prison remodel, where everything you could work on / tamper with was set in a secured chase. (Not your usual situation).

I also like the mention of less projection ... a little more room in the bath is never wasted.

Also mentioned was a flushometer. While I actually like that idea ... does your usual household water line supply enough water for that to work? The pipes I see on commercial units look like they're 1" or even larger.

As to the drain issue .... I'm not sure what a 'trap primer' is. While I am here asking questions, I do intend to have a real plumber do the work. Let me put it this way .... the effort and time I spent learning my trade has given me a great respect for every trade.

The 'shower' thread pointed out the need for a second drain in the bath. I can accomplish that (killing two birds with one stone) by having the lavatories drain into 'floor sinks,' which can connect to the sewer separate from the shower drain.

I'll have to get a sketch scanned and posted here, but I'll try to describe my proposed layout:

Imagine you're standing in the doorway, looking in. You are looking across the 8ft. dimension. About two feet to your left is one wall. Along that wall are, in sequence, a lavatory/ counter, a hair-wash sink, and the toilet.
On the right is a narrow set of shelves (linen closet) and a glass partition for one side of the shower area. After that is an 'aisle' between the shower and the tub, and then the tub. The tub is arranged with the short side toward the toilet, and the long side facing the shower area.

With the combination of a worn-out sewer line and a crawl space, I have exceptional freedom to run things as I wish.

11-21-2011, 05:53 PM
Tankless flushing toilets generally require one of two things: an internal pump or a water supply large enough to provide a surge of water. For the later, that's generally something in the 1" or larger water pipe all the way back to the main supply. There are ways to circumvent this, but you need space and somewhat of a kludge.

01-10-2012, 10:41 AM
I am redoing my bathroom and have decided to go the wall mounted Toto or geberit route. I just got back from a business trip to Amsterdam and most of the toilets there are this design. What was unique about them was that the walls were never flat all the way to the ceiling, the extra 2" that protrudes from the 6" stud that is required for the in wall tank was extended a couple inches to make a nice little shelf where the top of the tank ends. It was usually a nice granite shelf. I am considering doing this as well to give the bathroom a better look. It did not look as commercial as a standard installation. I should have taken a picture of one. I like the fact that the cleaning of the floor will be that much easier.