Specs are compiled from manufacturer listings and verified buyer reviews and can change over time — please confirm the key details on the product page before buying.
If your waste pipe leaves through the back wall instead of the floor, a standard toilet simply will not fit — and that is the whole reason you are here. A back outlet toilet (also called a rear discharge or back flush toilet) sends waste horizontally out the rear, so you can add a bathroom over a concrete slab, in a basement below the sewer line, or in a shop building without breaking up the floor. The one number that decides whether any of these will work in your home is the rough-in: the measurement from the finished wall to the center of your drain outlet. Get that number right and the rest is easy.
I’m Mohammad Maruf — the founder and writer behind KitchPrep. This guide is built by comparing the manufacturers’ published specifications and the patterns across verified customer reviews, so you get each pick’s real strengths and trade-offs instead of marketing spin.
Every pick below was checked against real owner experience, from basement installs to weekend cabins, so you can match the right bowl height, flush volume, and drain setup to your space. This breakdown of the best back outlet toilet covers rough-in fit, flush gallons, and rough owner feedback.
Our Picks at a Glance
How To Choose The Best Back Outlet Toilet
A back outlet toilet solves a plumbing problem, not a style problem. Before you compare flush volumes or seat shapes, confirm the waste can actually leave your room the way the toilet sends it. Waste leaves a rear discharge toilet horizontally through the back of the bowl, so you need either a wall drain already in place or a macerating pump (a device that grinds waste and pushes it uphill or sideways to your sewer line). If neither exists, a pump-equipped system is the answer.
Start with your rough-in measurement
Rough-in is the distance from the finished wall behind the toilet to the center of the drain opening. Rear discharge toilets list this number because a mismatch means the toilet will not seat against the wall correctly. The back outlet models here run from a 7-inch rough-in up to a standard 12-inch rough-in, so grab a tape measure before you order. If your measurement is off by more than an inch, no amount of adjusting will fix the fit.
Decide if you need a pump
If your new bathroom sits below the main sewer line — a basement, for example — gravity cannot carry waste away. A macerating pump (a grinder that turns waste into slurry and pushes it up and out) behind the toilet handles that, and the models with built-in pumps here can lift waste several feet vertically and far more horizontally, which opens up basements and additions that gravity toilets cannot serve. If you already have a wall drain at the right height, a standard gravity rear discharge toilet is simpler and cheaper to run.
Match the flush volume to your household
GPF stands for gallons per flush. A full flush around 1.28 to 1.6 GPF clears solid waste, while a half flush around 0.8 to 1 GPF handles liquid waste and saves water on every trip. Dual-flush toilets give you both buttons. Single-flush models keep it simple with one lever. For a busy family bathroom, dual flush saves the most water over a year; for a guest or shop bathroom, a single strong flush is often all you need.
Pick the right bowl height and shape
Standard bowls sit between 15 and 17 inches, while comfort-height models reach 18 to 19 inches — easier on knees and hips for seniors or anyone with mobility challenges. Elongated bowls give more room front to back; round bowls save space in tight bathrooms. Both are fine, but measure your available depth because a longer bowl eats into floor space.
Quick Comparison
| Model | Best For | Flush | Bowl Height | Weight | Amazon |
|---|---|---|---|---|---|
| Simple Project 600w Macerating Toilet System★ Best Overall | Basements below the sewer line | Macerating pump system | Not listed | 86.2 lb | Amazon |
| SUPERFLO Rear Outlet Toilet 19 Inch TallComfort Height Pick | Height and comfort | 1.28 / 0.8 GPF dual | 19 in | 92 lb | Amazon |
| Simple Project Rear Discharge Toilet 19″ ADABiggest Flush Pick | ADA-height access | 1.6 / 1 GPF dual | 19 in | 90.4 lb | Amazon |
| SUPERFLO 19” High Round Tall Toilet | Tight basement projects | 1.28 / 0.8 GPF dual | 19 in | 88 lb | Amazon |
| Compact 16.5” Two-Piece Rear Outlet Toilet | Narrow bathrooms | Eco-friendly flush | 16.5 in | 79 lb | Amazon |
| Rear Outlet Toilet with Tank (MaceratingFlo) | High-rise and compact spaces | High-efficiency flush | 16 in | 78 lb | Amazon |
| Skirted & Elongated Rear Outlet Toilet | Elongated seat comfort | 1.28 GPF tornado | 17.6 in | 101 lb | Amazon |
| Swiss Madison SM-2T120 Calice | Looks and build quality | 1.6 / 1.1 GPF dual | 15-17 in | — | Amazon |
| ARES 18″ Tall Rear Outlet Toilet | Accessible comfort height | Rimless 360° flush | 18 in | 110 lb | Amazon |
| Maxwell Wall Hung Back Outlet Combo | Wall-hung replacements | 1.28 GPF | 15 3/4 in | 105 lb | Amazon |
In‑Depth Reviews
1. Simple Project 600w Macerating Toilet System, Silent & Powerful
Our pick — over 4.5★ from 70+ verified ratings; the strongest balance of quality and price.
A 600w macerating pump that lifts waste 29 ft vertically and 295 ft horizontally.
For anyone finishing a basement or adding a bathroom below the main sewer line, this is the system that makes the whole project possible. A macerating toilet uses a pump to grind waste and push it uphill and sideways, and this one runs that pump with a 600w motor (the motor’s power rating, and a bigger number here means stronger push). It lifts waste up to 29 feet straight up and pushes it 295 feet horizontally. That reach is what lets you place fixtures far from the main stack instead of directly above the sewer.
What makes it flexible is the four water inlets — connection points that let you tie in a shower, laundry sink, wash basin, and more into the same unit. Owners in basement builds report it handles a raised shower, a tub, a sink, a washing machine, and even an ice maker on one system. As one buyer put it about their install: “8-9ft lift, 15-20ft downhill run to septic.” If you have ever priced a name-brand macerating system, the value angle here is real — this one comes in well under the brand-name equivalents owners mention comparing it against.
The honest trade-off is the small hardware. Owners find the pump itself quiet and reliable, but the flexible toilet connector that ships with it has leaked on some installs and been replaced with standard PVC and a rubber coupling. Directions are described as vague, so budget time to watch a fitting video first. Weighing 86.2 pounds, it is lighter than the 92-pound SUPERFLO gravity model above, though the two are close on the scale. At 4.6 stars across 70+ ratings, it is the highest-rated system here, and the install-friendly design is what wins people over.
Where It Pulls Ahead
- 600w macerating pump lifts waste 29 ft vertically and 295 ft horizontally
- 4 water inlets let you connect a shower, sink, and laundry to one unit
- Goes in below the sewer line without breaking concrete
- Runs quiet thanks to stainless steel macerating blades
Worth Knowing
- Included flexible toilet connector has leaked on some installs
- Instructions are thin; rely on install videos
- Tank seat is plastic, not a premium lid
Best for: Basement and below-sewer bathrooms where gravity cannot drain waste.
Think twice if: You already have a wall drain at the right height — a simpler gravity toilet will cost less to run.
2. SUPERFLO Rear Outlet Toilet With 19 Inch Tall Toilet Rear Discharge
A 19-inch bowl height, above the standard 15-to-17-inch range.
If bending low is the problem, this is the one to look at first. The bowl sits at 19 inches tall, well above the standard 15-to-17-inch range, which makes it easier to use for seniors or anyone with mobility challenges. It measures 27″D x 17″W x 34.3″H overall, and against the Simple Project ADA model it is the larger footprint by a noticeable margin. The P-Trap (the curved pipe that holds a water seal to block sewer gas) works with both rear drain and wall drain setups, and you can add a macerating pump later if your layout needs one.
The dual-flush button lets you pick a full 1.28 GPF flush or a half 0.8 GPF flush, so liquid trips use less water. That 0.8 GPF half flush is the lowest half-flush volume among the dual-flush models here, which matters if water use is a priority. The soft-close seat (a hinge that lowers the lid gently instead of slamming) keeps the bathroom quiet, and the top-mounted design makes the tank easy to reach for maintenance.
What wins people over is the build and the flush — owners describe a strong, quiet flush that clears waste in one pass. The one recurring gripe is the seat itself, which some find flimsy for the price, so a seat upgrade is worth budgeting. An owner who did not want to cut concrete summed the appeal up plainly: “Needed to add a toilet to our weekend getaway shop house, but didn’t want to cut the existing concrete.” It carries a 4.5-star rating across 100+ reviews.
The fit note: At 27 inches deep it needs real floor space behind the wall — measure before you commit. It is a compact-looking unit but not a small one.
Height leaders: The best balance of tall comfort height, dual flush, and broad installation flexibility.
Look elsewhere if: You want the seat to match the toilet’s quality from the start.
3. Simple Project Rear Discharge Toilet, 19″ ADA Tall Toilets for Seniors
A 1.6 GPF full flush and a 24.4-inch depth, both ahead of the SUPERFLO 19-inch.
This is the model to compare directly against the SUPERFLO 19-inch above, because they solve the same problem differently. Here the full flush is 1.6 GPF and the half flush is 1 GPF — both 25% above the SUPERFLO’s 1.28 and 0.8 GPF. If you have ever run a toilet twice because the first flush was thin, that extra water per press is the point. The bowl also sits at 19 inches tall for the same easier-standing benefit.
It measures 24.4″D x 14.5″W x 33.4″H, which makes it the shallower of the two by several inches, and at 90.4 pounds it is lighter than the 92-pound SUPERFLO. That shallower depth matters in a small bathroom where a long bowl crowds your knees. One number to check before ordering: the center of the rear drain outlet sits 7.5 inches from the ground, so confirm your existing pipe lines up at that height.
Buyers report the finish and the fit favorably, with the assembly going together cleanly. The catch is quality control on accessories — an owner reported missing bolts and fittings that sent them hunting for hardware, while another noted a small leak the seller refunded in full. The good news is the after-sale support is repeatedly called out as responsive, which softens the rare rough unit. It holds 4.3 stars across 18+ ratings.
Rough-in reminder: That 7.5-inch outlet height and the 24.4-inch depth are the two specs to match against your plumbing before you buy.
Pick it for: A stronger dual flush paired with a taller bowl in a tighter floor space.
skip it if: You want the widest possible cushion of owner reviews — this one has far fewer than the top pick.
4. SUPERFLO 19”High Toilets Round Tall Toilet, Rear Outlet Toilet
A 19-inch round bowl with a 0.8 / 1.28 GPF dual flush for wall-drain basements.
Circled out for a concrete-floor basement where the drain already lives in the wall, this round-bowl model keeps thing simple. The comfort height sits at 19 inches, and the dual-flush system uses 0.8 or 1.28 gallons depending on which button you press. A siphon flush pulls waste through a glazed trapway, and owners say it clears clean without the double-flush some rear discharge toilets need.
The slim round shape is a plus in a small basement bathroom where a longer elongated bowl would crowd the room. The slow-drop lid kills the lid slam, and the extension pipe is included so you are not chasing a separate part.
The catch here is consistency. A couple of owners hit fitment and hardware snags — one returned the unit unopened over a fit mismatch and ran into a restocking fee, while another flagged gasket and fill-valve issues during install. Those reports are the exception rather than the rule, but they do mean you should test the seal and connectors early. It rates 3.9 stars across 17+ ratings, the lowest here, so weigh that against the lower price tier.
What to know: This one is for the DIY installer who is comfortable swapping a gasket or fill valve if the factory part disappoints, and who wants a compact tall bowl over a wide one.
Reach for this if: You have a wall drain in a small concrete-floor basement and want comfort height without a big footprint.
Consider the top two instead if: You want the most consistent out-of-box hardware and the strongest review record.
5. Compact 16.5” Two-Piece Rear Outlet Toilet with Extension Pipes
A 16.5-inch bowl with a 7-inch rough-in, the shallowest drain set here.
Not every back outlet install needs height or a pump — sometimes it just needs to fit. This one stands at a compact 16.5 inches and uses a 7-inch rough-in, the shallowest drain set here, so it works in narrow rooms where a standard-depth toilet would jam against the wall. It weighs 79 pounds, one of the lightest in the group, and ships with two types of extension pipes so you can match whichever outlet you have.
The glazed surface is smooth and repels grime, and the soft-close seat stops the lid from banging. The eco-friendly flush keeps water use down while still clearing the bowl. With a round shape and a 26.1-inch depth, it stays out of the way in a small powder room or guest bath.
Now the honest part: the seat that comes in the box is a weak spot — owners call it a complicated assembly and suggest swapping it, even though they rate the toilet itself as solid. That is a minor, fixable gripe on an otherwise well-liked unit. Packaging and shipping are called out positively, which matters for a heavy ceramic item. It sits at 4.4 stars with a smaller base of 15+ ratings.
Small-space verdict: For a tight bathroom, that 7-inch rough-in and 16.5-inch height are the two numbers that decide whether this works where nothing else will.
Best for: Narrow bathrooms and small powder rooms that need a low, shallow rear-discharge bowl.
Look past it if: You want comfort height — this sits below the standard range.
6. Rear Outlet Toilet with Tank: Powerful Flush & Space-Saving Design
A 16-inch rear-discharge toilet with a 2-year manufacturer warranty.
Built for apartments, basements, and older renovations where a bottom-outlet toilet simply will not work, this model pairs a rear discharge design with a compact 26-inch depth and a 16-inch height. It weighs 78 pounds, the lightest in this lineup, and includes an extra extension pipe so the install can adapt to awkward layouts. A finely glazed surface keeps it easy to wipe down, and the manufacturer backs it with a 2-year warranty.
The flushing mechanism is designed to clear waste in one pass without a second press, though a couple of owners found the flush weaker than they hoped and had to work at it. That said, the customer service story is the standout — when a tank arrived without the flush lever hole, the company shipped a replacement tank right away, and owners describe support that goes well beyond the norm. Packaging is repeatedly praised for protecting a heavy ceramic shipment.
The one installation snag worth planning for is the gasket: sealing it to the pipe takes patience, and cutting the connection pipe is not advised since it is not a true 3-inch pipe. Owners who worked through that reported it sealing fine in the end. It rates 4.2 stars across 41+ ratings.
Flush reality check: The rear-discharge flush here is adequate rather than forceful — fine for a home theater bathroom, less ideal if you want maximum power per press.
Lean this way if: You want a lightweight, compact rear-outlet toilet backed by a real 2-year warranty and strong service.
Think twice if: Your priority is the strongest possible flush with no extra effort.
7. Skirted & Elongated Rear Outlet Toilet with 7″ Rough-In
A 17.6-inch elongated seat with a skirted trapway that hides the plumbing.
For anyone who finds round bowls cramped, this one swaps to a 17.6-inch elongated seat that gives more room to sit. The skirted trapway hides the plumbing behind a smooth panel, so there is no exposed pipework to dust around, and the fully glazed interior keeps the flow moving. A 3-inch outlet diameter and 7-inch rough-in let it fit rear-drain setups, and it ships with both flexible and hard extension pipes so it can pair with a toilet pump if needed.
The flush is a 1.28 GPF tornado design, which swirls water around the bowl rather than dumping it from the rim. Owners describe the flush as getting the job done, though at least one found it less forceful than hoped. The elongated seating and quiet soft-close hinge win the most praise, and the included warranty — a 1-year replacement and a 2-year repair — covers the mechanicals.
Ceramic this size does not travel lightly, and a small number of units have arrived scratched or cracked. That is a shipping risk rather than a design flaw, so inspect the bowl on arrival before you discard the packaging. At 101 pounds it is the heaviest of the mid-tier picks, so plan for a two-person lift. It holds 4.5 stars across 20+ ratings.
Why owners rate it: The elongated comfort and the skirted look are what stand out, along with a customer service team owners say responds fast and well.
Choose this if: You want the extra room of an elongated seat plus a clean skirted exterior around a 7-inch rough-in.
Pass if: You need a compact round bowl in a very tight room.
8. Swiss Madison SM-2T120 Calice Two Piece Elongated Rear Outlet Toilet
A skirted, elongated rear-discharge toilet on a standard 12-inch rough-in.
Most rear outlet toilets look like plumbing. This one looks like furniture. The skirted trapway hides the pipe for a clean silhouette, and the fully glazed interior prevents clogs while keeping water flowing freely. It uses a standard 12-inch rough-in, which is the most common set here, so it drops into many existing setups without an extension splice. The dual flush offers a low 1.1 GPF or a fuller 1.6 GPF depending on the button.
The elongated bowl adds front-to-back room, and the standard height sits between 15 and 17 inches for a familiar feel. Owners rate the quality and the appearance at the top of what buyers mention most, and the design is repeatedly compared to premium European fixtures. One reviewer noted it plainly: “Best looking rear outlet toilet I have seen.” It pairs easily with a macerating pump for a basement install.
The honest catch is the water level in the bowl, which sits low. That is the trade-off of saving water — a couple of owners note the shallow bowl means occasional scrubbing, so if you want a deep water spot, look at the 1GPF half-flush Simple Project again. Installation instructions are also thin, with no guidance on prepping the drain or mating the connector to the wall, so plan on some research. It carries a 4.2-star rating across 63+ ratings.
Installation heads-up: The included discharge tube can run short if you are pushing it through an exterior wall — owners have had to add a 4-inch schedule 40 pipe extension to reach.
Go here for: The best-looking rear outlet toilet with a skirted, easy-clean profile and a 12-inch rough-in.
Not your pick if: You want a deep water level in the bowl and detailed factory instructions.
9. ARES 18″ Tall Rear Outlet Toilet with Comfort Seat & Dual Flush
A rimless bowl that flushes all the way around, set at an 18-inch comfort height.
Accessibility is the headline: the bowl sits 18 inches tall with an 18.5-inch elongated seat, a combination that suits seniors and anyone who finds a low bowl hard on the hips. The rimless design skips the usual rim ledge and sends water around the whole bowl in a 360° pattern, so there is no hidden lip for grime to collect on. It ships with both flexible and rigid extension pipes and a back-mount design that fits 3-inch or 4-inch PVC or ABS couplings, with an adjustable rough-in to dial in the fit.
The fully skirted exterior (a smooth cover that hides the trapway) keeps it looking smooth and easy to wipe down, and it weighs 110 pounds — the heaviest unit here, so have a second person on hand for the lift. Quality and design are the two things buyers mention most, and the finish is called out as excellent on a clean install.
The honest caveat: the drain connection is the weak link. Owners mention the rubber connector not seating tight enough, causing leaks at the wall, and a weak flush that sometimes needs a second press. The silver lining is responsive support that diagnosed the issue and walked owners through a fix. It rates 4.0 stars across 26+ ratings.
Support note: If the rear connection drips, you are not stuck — customers note fast, helpful diagnosis from the maker’s team that resolved it.
Right for: A senior-friendly, rimless comfort-height toilet with an elongated seat and flexible rough-in.
Reconsider if: You want maximum flush strength from the start.
10. Maxwell 1.28gpf Wall Hung Back Outlet Combo
A wall-hung combo that mounts clean and frees up the floor underneath.
Different in shape from everything else here, this one hangs on the wall rather than sitting on the floor. The bowl is a 15 3/4-inch ErgoHeight ADA compact elongated design, and it adjusts to fit in-wall plumbing for extra comfort. It pairs a 2-inch glazed trapway with dual-fed siphon jets for a consistent flush, and a 3-inch flush valve drives strong water flow at 1.28 GPF. Waste leaves through the back, so it suits rear-discharge setups and wall-mounted plumbing.
The rear-wall mount keeps the floor clear underneath, which helps in a small bathroom or where floor space is tight around a door swing. It is built from vitreous china, and the front-mounted tank lever keeps the controls within easy reach. Owners replacing older wall-hung units report it fitting the existing bolts, and the pressurized flush system is described as working well and using notably less water than older models.
Now the catches: the seat is sold separately, so budget for one, and you will want the correct gasket because a wax ring is not recommended for this design. One owner flagged quality concerns, so inspect on arrival. It carries a 4.1-star rating across 17+ ratings.
One thing to buy: A seat and the proper gasket are not in the box, so add both to your order before installation day.
Go for this if: You need a wall-hung rear outlet toilet on ADA-compact height with an efficient 1.28 GPF flush.
Avoid the upgrade if: You want a floor-mounted toilet with the seat already included.
Understanding the Specs
Rough-In and Drain Height
Rough-in is the distance from the finished wall to the center of the drain opening. Rear discharge toilets list this because the waste exits horizontally, so a mismatch leaves a gap or won’t seal. The models here span a 7-inch rough-in on the compact and skirted picks up to a standard 12-inch rough-in on the Swiss Madison Calice. One Simple Project ADA model notes the rear drain outlet center sits 7.5 inches from the ground — that height, not just the wall distance, has to line up with the pipe you have. Measure both before ordering.
GPF and Flush Type
GPF stands for gallons per flush. A full flush around 1.28 to 1.6 GPF clears solid waste; a half flush around 0.8 to 1 GPF handles liquid and saves water. Dual-flush toilets give you both buttons, while single-flush and rimless designs use one lever. A tornado or rimless flush directs water around the bowl for broader coverage, while a siphon flush pulls waste through the trapway. More water per flush generally means stronger clearing, which is why the Simple Project ADA model’s 1.6 GPF full flush leads the dual-flush group here.
FAQ
How do I measure rough-in for a back outlet toilet?
Do I need a macerating pump for a rear outlet toilet?
What does GPF mean on a back flush toilet?
Is a 19-inch tall toilet good for seniors?
Can a rear outlet toilet connect to an existing floor drain?
How long does a back outlet toilet last?
What is the difference between rear discharge and back outlet?
Can I install a back outlet toilet myself?
What rough-in does the Swiss Madison Calice need?
Do rear outlet toilets come with a seat?
Final Thoughts: The Verdict
The winner for most below-sewer and slab projects is the Simple Project 600w Macerating Toilet System — its 600w pump lifts waste 29 feet up and 295 feet across, and the four water inlets let you fold a shower and laundry into the same line. It is the highest-rated system on this list, and if you want the widest cushion of owner experience backing your purchase, this is the one to reach for. If you already have a wall drain and want height plus a bigger dual flush, the Simple Project Rear Discharge Toilet 19″ ADA is the pick, with its 1.6 GPF full flush (1.6 gallons per flush). And for a narrow room where nothing else fits, the Compact 16.5” Two-Piece Rear Outlet Toilet gets you in with a 7-inch rough-in and a 16.5-inch height.
How We Picked
We do not accept paid placement. Every pick is matched to a real buyer and a real use-case; we do not hands-on test units.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of September 2026. Pricing: not shown on this page (it changes often); check the current price via the retailer link.
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