Kitchen Sink Plumbing Rough-in Dimensions (Explained) | (2022)

Are you building a new house or plan a major kitchen remodeling? One of the most important things to take into account is the rough-in plumbing. Even the tiniest mistake during this stage can cost you a fortune to fix, so make sure you get the plumbing rough-in dimensions right.

The standard kitchen sink plumbing has the kitchen sink drain about 28 inches from the floor. However, the height can vary based on the height of the counter and the depth of the sink bowl. That’s why the rough-in dimensions usually place the drain at a height between 20 and 24 inches.

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What is Rough-in Plumbing?

Rough-in refers to that stage of a construction project when electrical, mechanical, and plumbing lines are brought in. Thus, rough-in plumbing is the process of installing water lines, sewer pipes, plumbing vents, and connections.

Most rough-in plumbing is done when you’re building a home from scratch, but heavy home renovation projects that involve a change in the original plumbing can include some rough-in.

The entire rough-in plumbing system focuses on bringing clean water into your home and getting wastewater out.

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Rough-in Plumbing for Kitchen Sink

As explained above, the rough-in plumbing for a kitchen sink involves laying out all the pipes that won’t be visible once the sink is installed. They include the hot and cold water supply, the drain pipe, and the vent, which is normally part of the drain.

These parts are routed and secured to the kitchen’s framing, then covered with caulk or drywall. All you’ll see after the rough-in is the stub-outs, which are those short pipes sections protruding from the wall, where the sink’s faucet and drain will connect.

When installing rough-in plumbing for the kitchen, it is important to calculate the height of the water lines, but above all, the height of the drain – an improper drain height can lead to drainage issues that are a pain to fix.

Factors to Consider About Sink Drain Rough-In Height

Vent height

The drain vent of your kitchen sink should be positioned at 6 inches above the fixture’s flood level rim before offsetting horizontally.

P-trap height

The U-bent section of the P-trap should go below the wall drain level, allowing wastewater to go down and then up again as it drains. This layout is important to prevent sewage gases from leaking into your home.

Considering that a standard kitchen has an 8-inch deep bowl with a wall drain located about 28 inches above the floor, you should calculate a height for the bottom of your P-trap of about 16-1/2 to 18-1/2 inches.

An important thing to keep in mind is that this height is always calculated from the floor level, not from the bottom of your kitchen cabinets. If you want to use the space under your sink for storage, remember that the P-trap is located between 14-1/2 inches and 16-1/2 inches from your kitchen cabinet floor.

Type of sink and countertop

Lastly, you should consider the type of sink you want in your kitchen, the type of countertop, and how you plan to install them.

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We mentioned already that standard kitchen sinks have a bowl depth of 8 inches. However, considering that all drain plumbing measurements must be based on the sink’s depth, you should tell your plumber the actual depth of the sink you want to install.

For instance, mounting a 9-inch deep stainless steel or granite composite sink under a granite countertop will effectively make the sink 10-1/4 inches deep. Likewise, a 9-inch deep porcelain kitchen will effectively have a depth of about 8 inches if you mount it over granite or hardwood tops.

Kitchen Sink Height

We talked about kitchen sink bowl depth, but another important factor to consider when planning the rough-in layout is the height of the kitchen sink.

There is no set-in-stone standard, with homeowners preferring to decide the height of the sink based on the height of the people living in the home.

Considering the average height of kitchen cabinets, the average kitchen sinks stand about 36 inches high. However, the range can vary by as much as 10 inches, generally between 29 and 39 inches in height.

Standard Kitchen Sink Drain Rough-In Height

Since there is no building regulation for the minimum kitchen sink height, the standard kitchen sink drain rough-in height can also vary, generally from 20 to 24 inches. Slight variations below or above this range are acceptable for sinks installed at non-standard heights.

DIY: How to Rough-in a Kitchen Sink Drain

Roughing in a kitchen sink drain is a plumber’s job because even the slightest mistake can result in disaster. However, if you have good plumbing skills and want to save some bucks, here’s how you can rough the kitchen sink drain yourself.

Tools & Materials

  • 2-inch PVC drain pipe
  • Sanitary tee
  • Sink vent
  • Hacksaw
  • Drill
  • 2-1/4-inch drill bit
  • 1-5/8-inch drill bit
  • Plastic pipe cement
  • Marker
  • Tape measure

Step 1 – Plan the layout of your rough-in drain

Considering the sink’s height and sink bowl depth, mark a point on the stud behind the sink that is at least 12 inches below the bottom of the sink. This height will give you plenty of space to install the P-trap when mounting the sink later on.


From this marked point, plan the route of the sink’s drain line to the point where you can connect it with a larger drain pipe, such as a toilet drain or the main sewer line.

Step 2 – Install the drain pipe

Use a saw to cut a length of 2-inch PVC pipe that suits your measurements. Then, drill a 2-1/4-inch hole in the studs and floor plates beneath the sink. When you’re done, route the drain pipe through these holes, maintaining a minimum downslope of 1/4 inch per foot toward the sewer.

When the sink drain pipe meets the larger drain line or the sewer, use a sanitary tee (2 x 2 x 1-1/2 inches) to connect the two pipes. Place the tee so that the 2-inch ports connect the drainpipes, leaving the 1-1/2 port empty (this port will connect to the vent).

Glue the joints with plastic cement and leave them to dry before proceeding.

Step 3 – Determine the kitchen sink drain vent route

The drain vent should rise from the point where the two pipes connect and then connect to the main vent stack. Determine the best route, considering that any horizontal sections must maintain a 1/4-inch-per-foot slope toward the sink.

Step 4 – Install the vent

Use the 1-5/8-inch drill bit to drill holes in the studs and wall plates to accommodate the vent. The number of holes and their location will vary based on the vent routing layout you’ve planned in step 3.

After you’ve drilled all holes, route the vent and connect it to the main vent stack by cutting the vent stack at a point above the highest fixture in your house. Then, connect the vent to the 1-1/2 port on the tee connecting the sewer and sink drain pipe. Seal all joints with plastic cement and let them dry before continuing with your other kitchen plumbing projects.

Related Queries

While the information above can give you a good insight into kitchen plumbing rough-in, you might still have some questions. We’re answering some of them below.

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How far from the wall should a sink drain be?

There is no mandated minimum distance you should maintain between the sink drain and the wall. Thus, any distance is okay as long as you can make the connection.

What size are kitchen sink water lines?

Kitchen water lines have two diameters. The main pipes, which are the ones carrying water from the city supply or a well into your house, have a diameter of 3/4 inches. These lines can be made of copper or galvanized steel.

Exterior water lines start as one line from the main water supply that splits into two when it reaches the water heater. One line will carry cold water and the other hot water to your kitchen (or bathroom) sink.

The pipes under the sink, which are actually the hot and cold water hoses connecting to the main lines, have a diameter of 1/2 inches.

What is the standard kitchen sink size?

Most kitchen sinks have a standard size ranging from 30 to 33 inches. However, the range is broader, and you can find kitchen sinks ranging from 24 to 36 inches. Most sinks that are up to 30 inches long have one bowl. Double sinks can have anywhere from 32 to 36 inches.


Knowing the kitchen sink plumbing rough-in dimensions is essential if you don’t want to have drainage problems after installing the sink. Keep in mind, though, that these numbers aren’t set in stone. You must always calculate the right dimensions and pipe layout based on your circumstances, including the sink’s depth, its height, and the height of your under-sink cabinet floor.

Have you ever installed rough-in plumbing before, or is this your first project? Share your thoughts in a comment.


What are the rough in dimensions for a kitchen sink? ›

The proper kitchen sink drain rough in height is 20 to 24 inches.

How do you rough in plumb a kitchen sink? ›


How high should kitchen sink supply lines be? ›

Supply lines are usually placed high enough from the floor to accommodate a standard sink faucet or toilet. For example, this means that most water supply lines will be installed around sixteen to twenty-one inches from the ground for a sink faucet.

How high is a sink drain rough in? ›

Rough-in plumbing is usually placed at a somewhat lower height, between 18 and 20 inches, to accommodate varying counter heights and sink depths and leave plenty of space for the P-trap and necessary connections.

How do you measure kitchen sink plumbing? ›

To check the kitchen sink drain size, take a measuring tape and place it across the center of the drain hole. That way, you'll get the maximum width between two opposite points. This should be the exact size of the drain opening for your sink.

How high should sink water lines be? ›

The water supply line runs out of the wall into a hole in the back of the vanity, typically placed at a height of 22 to 24 inches from the finish floor.

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

Single Sink Space From the Wall

For most people, that minimum distance is at least 20 inches, measuring from the centerline, the NKBA recommendation. Adding a few inches more than 20 may make cleaning and using the sink easier.

How do you run a sink drain pipe? ›

how to plumb a new sink drain - YouTube

What is needed for plumbing rough in? ›

A plumbing rough-in means that all water supply and drain pipes have been run through bored holes in the studs and other framing members and that all pipe connections have been made. No sinks, faucets, drains, or other fixtures and end elements have yet been installed at this phase.

How far under a sink can the P trap be installed? ›

Maximum Distance

According to the International Residential Code, the maximum vertical distance between the sink drain and the entrance to the p-trap is 24 inches.

How much does a sink drain need to drop? ›

The ideal slope of any drain line is ¼ inch per foot of pipe. In other words, for every foot the pipe travels horizontally, it should be dropping ¼ inch vertically.

What is sink rough in? ›

A plumbing rough-in means that all water supply and drain pipes have been run through bored holes in the studs and other framing members and that all pipe connections have been made. No sinks, faucets, drains, or other fixtures and end elements have yet been installed at this phase.

How far from wall should sink drain be? ›

Discharge hole (vertical): Drain located at floor height; distance is zero. Fixture (side to side buffer): Measured from center of the toilet to either side, minimum. clearance is 15 inches to any wall or other fixture; 18 inches is recommended if the bathroom layout allows for this.

How do you rough in a farmhouse sink? ›

How To Install a Farmhouse Sink | DIY Kitchen Remodel - YouTube


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