back to back toilet plumbing

Back to Back Toilet Plumbing – (Common Problems and Solutions)

Selecting the ideal toilet may be difficult, whether you’re remodeling your bathroom or building a new one. It might be difficult to figure out where to begin! Back to back toilets have been a trendy toilet style in the last few years. What does ‘back to back toilet plumbing’ mean?

Here is a comprehensive overview of back to back restrooms. Learn about the benefits and the need for it, as well as how to put it. Find out whether there might be any issues with back to back lavatory drainage.

What is Back to Back Toilet Plumbing?

A back-to-back toilet is a pair of toilets connected by a single wall. The common fluid, vent, as well as waste sources for the toilets are located on the same wall.

The material in a single pan travel to the other as you flush a single, and the opposite is also true. Before it hits the stack, a straight line is where the pans are joined.

If two bathrooms are put back-to-back, homes constructed before 1965 may utilize a twin sanitary tee to facilitate drainage. For setups utilizing restrooms with bulk capacity flushes, the double tee might not work.

The water in the bowl is forced out through the toilet by bulk capacity flushes. A strong flush may result in a little water entering the waste pipe of the toilet located right behind the one being flushed after passing through the second tee.

When installing back-to-back toilets, the fresh build employs a 45° dual wye connection. By directing the water downhill, the “Y” connector prevents direct flow through the opposing waste line.

When is Back to Back Toilet Plumbing Necessary

When is Back to Back Toilet Plumbing Necessary?

The following will need to be done if you ever need to get to the piping that powers these devices back-to-back.

You’ll either need to draw a tub or reach down to the story beneath to get to the drain pipes; for a first story installation, this would be the cellar; for a second floor installation, it would be the first-story ceiling.

The bathroom valve’s escutcheon panel may frequently be removed for maintenance. However, you would need to cut the old one away and solder on another one in the event that you ever needed to get rid of the valve when the grout hole was too tiny to allow for appropriate access to the piping.

Typically, accessing the valve requires cutting an opening through the wall from the opposite side to the wall, repairing the damage from the opposite end of the barrier, and then patching the drywall.

You might need to break through some tiles in order to replace the control panel because the wall is tiled on both sides. That is not meant to discourage you from performing back-to-back plumbers. A thing to think about in case anything does appear.

What are the Advantages of Back to Back Toilet Plumbing?

The use of pooled drains serves as an alternative to individual vents. In this setup, two toilets are connected to a single drainpipe that is connected to a main sewage line.

Sharing a drain throughout installation between two toilets might help save labor and supplies.

Although sharing drains can reduce the amount of area needed for several drainpipes, there may also be disadvantages. As an example, since scents might spread across the two linked toilets, they might become more common.

Additionally, there is a higher chance of blockages since solid waste leaving one toilet may impair the drainage of the other.

Savings on Expenses

You may save cash on construction and supplies by using the same drain.

Saves Space

Compared to installing separate drainage for every toilet, you can accommodate two bathrooms in a lot less room.

The Effectiveness of Water has Increased

The quantity of water used overall is decreased when two bathrooms are connected to a single drain and utilize a comparable quantity of water.

Simpler to Maintain

It is simpler to take care of cleaning the system when two toilets are joined to a single drain.

There will be Less Clutter

Less plumbing supplies and accessories are required when two toilets are connected to a single drain, which reduces the amount of clutter in the restroom.

How is Back to Back Toilet Plumbing Installed?

Upon the wall foundation plate, draw a line along the middle for the drain pipe. In addition to the drainage center range, draw another center line 4 inches towards the right of it as well as 4 inches towards the left.

Using the drill as well as the hole saw, create a two 1/4-inch cut at the middle of the plaster plate where the drain is located. Every water distribution point needs a 1-inch hole to be drilled in the wall plate’s middle.

In addition to the measurement of the ground joists, cut a length of a two-inch drain pipe at 24 inches in length. Attach a 2-inch drainage line’s dual sanitary tee with cement at the tip.

Into the two 1/4-inch openings, insert the pipe, and fasten it with belting and nails. Place the tee’s middle line 18 inches off the ground.

CPVC, as well as PVC 3/4-inch pipe, should be cut to a length of 22 inches, including the highest point of the ground joist. To every conduit, cement the appropriate 3/4-inch tee.

PVC pipe should be dropped through the correct hole, while CPVC pipe should be dropped via the left one. At an angle of twenty-one inches from the ground, fix the middle of the 3/4-inch tees.

Make your way to the level below and attach the cold and hot water lines, as well as the line for drainage, to the appropriate pipes. Pass a two-inch pipe via the roof opening and top plates. After installing the pipe, add cement at the bottom tip.

What are the Potential Problems with Back to Back Toilet Plumbing?


The drain needs to be particularly big to fit both garbage streams when two bathrooms are linked to a single drain. Alternatively, the limited drainage ability might result in blockage.


Water might overflow from a drain that is shared by two toilets. The spread of germs and other toxins makes this a health risk.

What are the Potential Problems with Back to Back Toilet Plumbing

Odor Problems

The potential for odor problems, when two bathrooms share a drain is another frequent worry. Poor ventilation might happen if two toilets share a drain because there is no route for air to move away from the bathroom. When sewage gas seeps back into the restrooms, this can happen.

Leaky Pipes

Water leaks might develop over time as a result of loose or broken pipes that link the two bathrooms to a single drain. This can result in flooding and is a huge hassle.

Increasing Water Intake

Since both toilets will consume the same quantity of water, having two linked to identical drains might result in greater water usage. The cost of your water may go up as a result.

Can Two Toilets Share the Same Drain?

Yes. If both bathrooms are linked back to back, they might share a single drain pipe. However, they can only do so if they stay at the identical end of the home. If your restrooms are located at both ends of your home, think about sharing the sewer line.

Current plumbing advancements make it feasible to connect two toilets to a single drain. A “wet vent,” which effectively merges two fittings into one pipe to save space and simplify the structure of the plumbing overall, is commonly used in this situation.

You should be aware that using the same drainage for two toilets might lead to significant issues. You should also make sure the drains are big enough to manage the fluid flow coming from the toilets.

What is a Back to Wall Toilet?

In contrast to a cistern, the back wall-mounted toilet is one in which the individual’s backrests flush with the wall while seated. The toilet pan will be in front of you once you enter the bathroom. However, the cistern, which stores the water needed for flushing, won’t be.

Back-to-wall toilets function similarly to normal toilets. The biggest distinction here is the fact that there’s a lot more room available once you approach the restroom stall. This is so that you will only be able to observe the toilet bowl since the cistern is out of sight.

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