Plumbing Diagrams and Layouts for Bathroom: The Ultimate Guide — Kevin Szabo Jr Plumbing - Plumbing Services│Local Plumber│Tinley Park, IL (2023)

Technology and modern conveniences are common in our homes today. In fact, the market for do-it-yourself home improvements is set to grow at a 4.5% CAGR through 2027. And one of the nooks in your house that needs improvement is your bathroom. They can be small or large, with all kinds of fixtures, including sinks, tubs, toilets, and showers.

Nothing beats the comfort and luxury of relaxing in your own bathroom. And you don't have to stick with the standard layout of only a few square feet. So, why not make use of all your space with the right professional plumbing services? Bathroom plumbing layouts are as important as the fixtures within them.

Your bathroom renovation is beyond the safety of your existing pipes. It also addresses issues like space and future needs. This guide will walk you through bathroom layouts, dimensions, and other considerations.

1. Choose the Right Plumbing Supplies

Your bathroom should be functional, safe, and efficient. That means you have a comfortable bathtub, smooth drains, and everything placed exactly where you need it. But that doesn't mean you have to spend a lot of money doing it. You can make plumbing fun and affordable if you want to.

Designer plumbing supplies are one thing. You can also add ergonomic bathroom layouts to them. Plumbing supplies from PlumbersStock distinguish your bathroom in any market. A few unique designs can help you raise the bar for your home.

Consider these materials for your plumbing plans:

  • PVC pipes. Use PVC pipes with a 3-inch diameter for the main drain and the small section connecting the toilet to the drain. Use a 2-inch one for vents and more drain lines.

  • Cast-iron pipes. Cast-iron pipes don't make a lot of noise compared to plastic pipes. That's why most homeowners prefer these materials. If you want one, make sure to leave the installation to the professionals.

  • Rigid copper pipe. This is the most common material used for water delivery lines. Standard plumbing for bathrooms is 1/2-inch pipe. For the best water pressure, run 3/4-inch pipe to the bathroom and only use half an inch for short lengths.

Your bathroom layout depends on the plumbing fixtures and fittings you select. So, you should get them as early in the process as possible. But do make sure that your plumbing supplies match your budget. You don't want to spend a lot on the materials only to be short in other aspects of your bathroom.

2. Select from Popular Bathroom Layouts

Spend some time considering your needs and designing an efficient bathroom layout. After that, you can begin arranging the components, such as the bathtub, shower, toilet, and sink. See which of the well-liked bathroom layouts below best suits your needs and home.

Three-Quarter Bath Layout (No Tub)

This efficient design for a guest bathroom has one sink, a toilet, and a shower. Having all plumbing on one wall reduces labor and material costs. This makes it the most cost-efficient layout in the list.

But since it's small, make sure you organize the space efficiently.

Full Bath Layout

A full bathroom has a shower, a sink, a tub or shower, and a toilet. This floor layout is the best choice if you have a small house.

Much like the three-quarter bath layout, the plumbing fixtures are all on one wall. A full bathroom also offers room for a large or double vanity.

Versatile Primary Bathroom Layout

This bathroom layout starts at 36 square feet. This is ideal if there are people sharing a bathroom, yet you have little space.

The plumbing fixtures are set on two walls, with the vanity and toilet on one side and the tub or shower on the other. Using a double vanity is space-efficient, with end shelves for more storage. Consider a walk-in shower as well, since it costs less because there isn't a door needed for it.

Large Primary Bathroom Plan

Spread out your fixtures in a 10 by 12-foot area for a more opulent bathing experience. To create a nice focal point, place the bathtub next to a window.

With this bathroom layout, you can have double vanities. This gives each of your family members their own space. You can also add a door to the toilet space, which also increases privacy.

Handicapped Bathroom Layout

Bathrooms for people with disabilities must be at least 3 by 5 or 15 square feet in size. The doorway is at least 32 to 36 inches wide, or 2.5 feet.

Since it's a handicapped bathroom, make sure the toilet and handle are closer to the ground. You should also have safety bars and other handhold supports.

3. Consider Rough-In Plumbing Dimensions for Bathroom

Remember that not all dimensions are absolute. Think of these dimensions as broad principles: they change based on your bathroom. If you want a more specific measurement, you can refer to the instructions that came with the fixture.

Toilet Rough-In Details

  • Supply line (height). The water supply pipe for the toilet should enter the space 8 and a quarter inches above the floor. The pipe for cold water only leaves a single hole 5 to 10 inches above the ground.

  • Supply line (horizontal). The hole for the water supply line should be 6 inches away from the center. To verify the location of the water supply connection, check the toilet.

  • Discharge hole from the back wall. The hole is 12 1/2 inches away from the back wall.

  • Discharge hole (vertical). The drain is at floor level; there is no distance.

  • Fixture (side-to-side buffer): There must be 15 inches of clearance from any wall or other fixture. Recommended size: 18 inches.

  • Fixture (front buffer): The clearance to the nearest obstruction, measured from the front rim of the toilet forward, is 21 inches. Recommended size: 30 inches.

Sink Rough-In Details

  • Supply line (height). There are two holes, 2 to 3 inches above the drain pipe.

  • Supply lines (horizontal). The distance between the centerline of one hole and the centerline of the other is four inches.

  • Discharge hole (vertical). Consider the drain pipe to be the vertical centerline at a height of 16 to 20 inches above the ground.

  • Fixture (side-to-side buffer). Minimum distance from centerline: 15 inches; recommended distance: 20 inches.

  • Fixture (front buffer). The required distance is 30 inches, with a minimum of 21 inches to the next barrier.

  • Placement of sink. At the rim of the sink, the sink should be around 31 inches above the floor.

Shower and Bathtub Rough-In Details

  • Discharge hole (vertical). The drain is at floor level; there is no distance.

  • Fixture (side to side buffer): The minimum necessary buffer is 18 inches.

  • Fixture (front buffer): The minimum necessary buffer is 18 inches.

4. Plan Vents and Drain Lines

Consider the thickness of the wall finishing material for new framing. For drywall, allow about half an inch; for wall tiles, allow another 3/8 inch.


Determine the location of the vents first. Each fixture's drain line should, in general, attach to a vent within a few feet of the fixture. Water never flows through a rear vent. You can also get wet venting in specific circumstances.


Your bathroom's new main drain line should descend to the floor below. You can tie the new bathroom into the house's main drain line in the crawlspace below if it is on the first floor.

The main drain should go through the first-floor wall and down to the crawlspace if it's on the second floor. You can connect a pipe to an existing drain line rather than install a new one if there is one close by.

5. Recognize Your Drain-Waste-Vent System

The hot and cold water lines can be set up in any practical way. Run a separate 3/4-inch line from close to the water heater to the shower. This lets you use another fixture without compromising the water pressure and temperature.

6. Find the Wet Wall / Shaft Wall

Every home has a "wet wall," also referred to as the "shaft wall." It houses the main plumbing drainage pipes and is thicker than an interior wall. It is where water lines and other plumbing lines are set. If you place fixtures on or near this wall, you can use fewer pipes and connections.

7. Slope

Most plumbing guidelines recommend a 0.25-inch slope per foot on a horizontal drain pipe. And some specify a 1/8 inch slope per foot for pipes with more than 3 inches in diameter. This helps your bathroom have a consistent water flow.

To Wrap it Up

Let's be real—not everyone is a designer. And not everyone needs to be. But, it is still important for you to understand the basics of design. That's if you're going to speak with confidence about the look and feel of a bathroom layout.

Discovering new bathroom layouts makes more efficient use of space. When you have the best plans in place from the start, you’ll be sure to end up with the perfect bath.

And remember: a bathroom isn’t only a place to get ready. Consider it your sanctuary. Make it feel like home by making the most of all the bathroom space you have.

Guest Contributor: Daniel


How do I get a plumbing diagram for my house? ›

Where to Find a Home Plumbing Diagram
  1. Ask the builder. If your home is relatively new and the contractor/builder that constructed it is still available, you may be able to get a copy of the “rough-in” plumbing diagram for the house. ...
  2. Check the county clerk's office. ...
  3. Ask a plumber to make one.
May 6, 2021

What size should bathroom plumbing be? ›

Bathrooms are usually supplied with 1/2-inch pipe. Run 3/4-inch pipe to the bathroom for maximum water pressure and use 1/2-inch for short runs only.

What is included in bathroom rough in plumbing? ›

A bathroom plumbing rough-in includes running the water supply and drain lines through bored holes in the wall studs and other framing members. A key part of the rough-in is making measurements and diagrams for the bathroom layout and the locations of the supply and drain lines for each fixture.

How many drain pipes does a house have? ›

All wastewater from your house is carried to the municipal sewer line by one main drain pipe that typically runs horizontally, but with a slight downward slope, under the lowest floor in your home out to the municipal sewer main or out to the septic field.

How do I find where pipes are in my wall? ›

Yes, stud finders are designed to find any obstruction in the wall including the water pipes. You can rely on a new model of a stud finder to help you detect water pipes for use around the house. Stud finders are quite affordable and reliable too when it comes to plumber work.

Can a shower and toilet share a drain? ›

Conclusion. In short, it is possible to connect the toilet drainage line and the shower drainage line, as long as they both have separate waste trap arms. However, do note that combining them may also lead to blockages, which can cause smells to come from certain drains.

How far should a toilet be from the wall? ›

Most codes require at least 15 inches (measured from the center of the toilet) from any side wall or obstruction and not closer than 30 inches center to center to any other sanitary fixture. (The NKBA actually recommends 32 inches.) There should be at least 24 inches of clear space in front of a toilet or bidet.

Can a toilet and kitchen sink share the same drain? ›

But you need to be careful with the connection because if not done properly, it can lead to a backflow of wastewater due to an airlock. Not only can the toilet and sink share the same drain, but in the USA, all plumbing fixtures are connected to one drain. It is convenient, cost effective and manageable.

How high should bathroom sink drain be from floor? ›

Sink discharge hole (vertical): About 16 to 20 inches above the floor; consider the drain pipe to be the vertical centerline. Sink side-to-side buffer: From the centerline, 15 inches minimum, 20 inches recommended.

What is roughing in? ›

Rough-in is the stage of a construction project when the various mechanical, electrical, and plumbing lines are brought in. Once the framing is up, the rough-in stage of construction begins. This is when lines are laid out, but final connections are not made until other stages of the project are completed.

What is the toilet rough-in for a toilet? ›

A toilet's rough-in size measures the distance from the back wall to the center of the drainpipe, otherwise called the toilet flange. This rough-in measurement usually comes in at 12 inches, but some bathrooms and toilets require 10-inch or 14-inch rough-in distances.

Do you replace bathroom floor or toilet first? ›

The bathroom fitters are unanimous—if you're looking for a high quality finish, with a better seal against water damage, then always tile the floor first.

How much does it cost to install a 2 piece bathroom? ›

'A full-sized bathroom that is added to an existing space will typically cost between $7,000 and $12,500 on average. 'Building an addition to house the bathroom will be more expensive, ranging between $14,000 to $30,000 on average,' she explains.

Can you go from one sink to two in bathroom? ›

It's entirely possible to replace a single sink with a double sink, although it requires a bit of work and money. Double bathroom vanities, sometimes called “his and her” sinks, can be more practical in situations where two people go through their morning routines simultaneously.

What is the strongest drain pipe? ›

HDPE/N 12 Corrugated Dual Wall Pipe – Strongest

It can be used in multiple applications but more commonly where a high strength rating is required.

How many toilets can you put on a 3 inch sewer line? ›

No more than four water closets or bathroom groups shall be installed on a 3" horizontal fixture branch.

How many toilets can be on a 4 inch drain? ›

Section 710 Drainage System Sizing
9 more rows

Where not to drill in a wall? ›

Avoid drilling near light sockets or outlets

Wires in the wall often connect vertically and horizontally behind outlets and sockets and can lead to electrocution. Hitting a pipe in the wall can cause flooding. A simple rule of thumb is to avoid drilling anywhere near where there may be electrical hookups or piping.

How do I find hidden water pipes? ›

Today, the best tool for the job is ground penetrating radar (GPR) as it accurately maps metal and PVC pipes. Traditional pipe locators use electricity and magnets to locate underground pipes.

How far behind drywall are pipes? ›

Limiting drilling depth to less than 1-1/4 inches is a good start to reducing the risk of damaging wiring behind the drywall. The 2018 International Residential Code also requires steel plates or sleeves to be installed to protect wiring that is run horizontally through the studs in the wall.

Does a shower drain have a pee trap? ›

Whether you have a standing shower or bathtub, it will always have a p-trap. The p-trap for showers is located underneath. Like the other fixtures, the shower drain p-trap prevents sewer odors from escaping your pipes.

Does water from shower go to sewer? ›

When your plumbing systems are in working order, your bathtub drains tub and shower water down your pipes and into your sewer. Your bathtub and toilet drain down separate pipes until they reach the main sewer line, which is the primary pipe to which all drains in your house lead.

Why is there a sewer smell coming from my shower? ›

There are several common causes for a sewage odor coming up from the shower drain, including a clog in the drain line, a dry or dirty P-trap, mold or biofilm build-up, and leaking drain lines in the walls, ceiling, or under the floor.

What does 14 inch rough in mean for toilet? ›

Toilet Rough In Dimensions: A toilet's rough-in measurement is the space between the wall behind the toilet and the center of the waste pipe. Standard toilet rough in dimensions are 12 inches but can be anywhere from 10 to 14 inches in some cases.

How far should a toilet be from the shower? ›


Leave at least 15" of space between the shower and toilet or other obstacle. If you have a swinging door, take into consideration nearby fixtures.

What is the sink next to the toilet for? ›

The bidet is often a basin that is situated close to the toilet in the bathroom, and it is used to clean yourself after using the toilet or when you need to freshen up or wash your genitals and anal area.

Are toilet and bathtub drains connected? ›

All the sinks, toilets, and tubs connect to a single drain pipe that leads to the sewer line under your house. This drain line carries all wastewater and sewage away from your home to the city's sewer system.

Can bath and shower waste join together? ›

Can bath and shower waste join together? Yes, but care should be taken during installation. Since both appliances use the same size pipework (40mm waste pipe), having them connect to the same discharge pipe shouldn't be a problem.

How far below the sink should the trap be? ›

Location of the P-trap

The International Residential Code, under the International Code Council, says that the P-trap must hang at a maximum height of 24 inches below the drain.

What height should a sink be from the ground? ›

What is a standard basin height? Measuring from floor to the top lip of the basin, the standard height of a bathroom basin is often quoted by the plumbing trade to be around 80-85cm.

How far from the wall should a bathtub drain be? ›

This hole should be 9 inches wide and extend at least 12 inches from the wall. If you're installing a claw foot tub, the drain line will be exposed, so the hole in the floor will need to be more precise.

What does roughing up a girl mean? ›

phrasal verb. If someone roughs you up, they attack you and hit or beat you. [informal]

What is roughing vs finishing pass? ›

The Roughing Passes setting allows you to add a small offset to all passes which precede your final pass. A final “finishing” pass will be added to the end of the AutoPass routine. This pass will remove the small offset leaving you with a high quality finish.

What is trim out? ›

Trim-out plumbing is the last phase in new construction plumbing. It's where the plumber installs the beautiful fixtures for your home, such as sinks, showers, and the toilet, as well as hooks up and installs the major appliances, such as your dishwasher and hot water heater.

What is the most common toilet rough-in? ›

The standard rough-in is 12 inches, though you may encounter 10-inch and 14-inch rough-ins in older homes. You should find the rough-in measurement in the new toilet's product information.

How do I know if I have a 10 or 12 inch rough-in toilet? ›

You'll need to measure vertically from the bare floor to the center of the waste drain to find the rough-in size of a wall-mount or rear-outlet toilet.

What is a toilet shroud? ›

A covering for the outer portion of a toilet concealing the fixture below the rim of the bowl. The covering consists of a flexible material which can closely fit the countours of the fixture which is either washable or disposable.

Does a plumber install a new toilet? ›

Professional Toilet Installation. Homeowners should hire a licensed plumber for toilet replacement in most cases. However, there are some instances in which a do-it-yourself (DIY) toilet installation, while challenging, can be done.

What time is best for a bathroom floor? ›

Specifically, ceramic and porcelain tiles are great options for bathrooms. Tile flooring is resilient, waterproof, available in a variety of colors and designs, and generally less expensive than other hard surface options. Porcelain tiles specifically absorb less water than any other ceramic product.

Do you install shower before or after flooring? ›

A shower only setup benefits greatly from having your flooring installed first or concurrently as the shower tiles will generally be placed at the same time as the rest of your bathroom flooring. This means that you need only install the door and the faucet after your bathroom remodeling is complete.

What is the labor cost to install a bathroom? ›

Labor Costs

About half of bathroom installation costs go to labor. This project requires many licensed subcontractors, including plumbers and electricians. Plumbers typically charge $75–$130 per hour, and electricians charge $40–$120 per hour.

How much does it cost to remodel a small bathroom? ›

The average small bathroom remodel cost is $6,500. You can expect to spend between $1,500 to $15,000, depending on the scope of the makeover, the materials, and whether you tackle some of the work yourself.

Why remodeling a bathroom is expensive? ›

You might be wondering why it's so pricey, and whether or not it's worth the investment. There are many reasons why a bathroom remodel may cost more than you think, including: inefficient layouts, complex plumbing systems, outdated design features and materials, high-end fixtures and appliances.

Do the blueprints of a house show plumbing? ›

When you buy house plans, no matter how complete and detailed they are, you won't see finished drawings for the electrical work, the plumbing, or the heating and air conditioning.

Do house plans come with plumbing plans? ›

Although plumbing fixtures are included in your home plans, the flow of water lines and sewer systems are site-specific and must be determined locally. You can discuss these details with your local builder.

What is a plumbing diagram called? ›

Plumbing and piping diagrams are project blueprints that include drawings and symbols of essential plumbing processes and components, including: Line sizes and locations. Valves.

Do blueprints show pipes? ›

The blueprint for the home will show where each plumbing fixture should go, but it's up to the plumber to connect the dots. The chances of the plumber taking the time to map out where each pipe was installed, is slim to none.


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