How To Draw A Plumbing Plan (Explained)

Disclaimer: This post may contain affiliate links, meaning we get a small commission if you make a purchase through our links, at no cost to you. For more information, please visit our Disclaimer Page.

The plumbing plan is a drawing that shows the location of all the pipes and fixtures of your plumbing system on your property.

The plan will show the fixtures, water supply pipes, drain pipes, vents, and other items. A plumbing plan can be used for many reasons such as when you are replacing or adding new plumbing fixtures to an area of the house.

To draw a good plumbing plan, whether, by hand or computer, you must consider how water will come in and leave the system. You can use symbols, arrows, lines, etc., to demonstrate the plan and water movement in the system.

What Are The Parts of A Plumbing Plan?

A plumbing plan on paper may look overly complicated. It seems even more complex when the water system is installed in the house, and you cannot tell which pipe leads where. Contrary to this notion, water systems, whether on paper or the walls of a house, are not as complicated.

You only need to understand the parts of the plumbing plan, and everything will seem easy. These parts indicate the path that water follows from where it enters the house, its distribution around the house, and how the wastewater is brought out.

A plumbing plan is split into three parts according to its functionality. These three parts include:

  1. Water Supply System
  2. Lines to the Fixtures and Appliances
  3. Drain System

Water Supply System

When making a plumbing plan, you must first determine where you’ll get the water for the particular establishment.

Determine whether you’ll get it from the municipality or from a borehole. This will help you choose a good entry point for the water into the building.

From the start, the water supply system will act as a foundation for the rest of the plan as it will determine the direction the water pipes will follow to distribute water through the house efficiently.

Lines to the Fixtures and Appliances

Fixtures are the fixed points for dispensing water. These include the sinks, bathtubs, showers, etc.

The appliances are the electronics that heat or cool the water. For example, water is directed to the heater or the fridge for heating or cooling.

These fixtures and appliances differ depending on the size of the house. So, when making a plumbing plan, you have to indicate all the lines leading to the fixtures and appliances in an uncomplicated manner.

Drain System

The drain system is responsible for removing wastewater and channeling it into the sewer or a place where it will be useful.

Drain pipes are positioned in a way that they are not easily blocked, or the dirty water doesn’t contaminate the clean water in case of a leak.

The design must incorporate factors like water volume, gravity, ease of repair, and other maintenance operations.

How Do You Draw A Plumbing Plan?

A plumbing plan eases the installation process and ensures that you don’t leave out important things or mix up the process.

It has to be clear how the water will come in and how the waste will go out. Paying attention to little details will eliminate the chance of water leakages and improper installation.

Here are some tips to help you draw a good plumbing plan.

Add all the details

Ensure that your drawing incorporates all the details, including the tiniest of it. This will eliminate the possibility of extra expenses during installation.

If you get everything captured in the plan, you’ll not have to visit the supply store multiple times.

Also, a detailed plan will give you a budget estimate so that you can plan properly before you commence installation.

Use color codes

These are globally recognized colors used to represent different things on a plumbing plan.

For example, the blue color on the pipes indicates that the pipe is carrying clean water, which can be used around the house. On the other hand, green-colored pipes carry wastewater and are mostly used to drain water.

Another color marking is purple. Pipes marked with purple carry reclaimed water which can only be used for irrigation purposes. Using such colors makes it easier to follow through with a plumbing plan without confusion.

Use Globally recognized symbols.

The plumbing plan is usually drawn to scale the real items on the ground. So, you’ll need to use the correct symbols for valves, interjections, etc., to show you the exact components of the plan. The symbols are important because they help you estimate the materials you need.

To draw a plumbing plan, you’ll need the following materials.

  • Colored pencils
  • Eraser
  • Grid papers
  • 30-60-90 degree triangle

After assembling all your materials, you’ll need to organize your drawing following a step-by-step guide until you get a good plumbing plan.

Step 1 – Determine a suitable scale for the pipes, fixtures, and all the fittings. Draw all the fixtures separately, a little far from each other as they appear in the building.

Step 2 – Mark the lines, starting with the drain lines, the vents, and then the supply lines to the different fixtures. Ensure that you mark them correctly using color codes so that you can easily identify them. Vents are indicated using dotted lines.

Step 3 – Indicate the sizes of each pipe and their fittings (mention the exact types). This makes it easy during purchases so that you know which sizes to buy.

Step 4 – Indicate the valve areas and the valve type, as well as the stops at each fixture.

In these four steps, your drawing will be complete. However, you may need to create several versions of the plumbing plan until the final plan meets your specifications.

How to Draw an Isometric Plumbing Plan?

An isometric plumbing plan represents all the fittings, pipes, and fixtures at a 45° angle. It’s an easy way to represent 3D designs on 2D drawings.

Mastering the skill to draw isometric plans is important for any plumbing professional as it makes it easier to read the designs.

An isometric plan is very simplified and less detailed yet drawn accurately to scale for easy implementation. The lengths of each pipe per scale must be indicated on the pipe accordingly as well as the sizes of each pipe.

In most cases, isometric drawings are used to explain the engineer’s thoughts to the plumber working on the ground. You’d easily have two plumbing professionals explaining to each other plumbing plans using isometric drawings.

However, if you’re working on a larger project where more details are needed, or a supervisor will check through, you’ll need to create a proper design that is easily understood.

In creating an isometric plan, there must be a point of reference. In the isometric drawing, the point of reference is always the north arrow from a compass. The compass is drawn with these directions: up, down, north, south, east, and west.

Once you’ve determined your north arrow, draw it or a parallel line as your mainline then other branches to it. The branches can show the other pipelines, which are drawn parallel to other arrows on the compass.

Another way to draw is to start by drawing a 90° angle and then bisect it. The line bisecting the angle forms a 45° angle, and so you can use that line as your point of reference.

The vents should be drawn in dotted lines. Other fittings should be indicated as well. Since the pipes are in different sizes, these sizes must be indicated at the side near the line.

You can draw an isometric plan by hand or by computer using different software applications. This depends on the complexity of the project and your proficiency in using them.


Water systems are a major part of an establishment and must be done well to ensure no leakage or blockages as the water comes in and leaves the building. That means, as a plumber, you must be in a position to create a detailed plumbing plan and follow through with it during the installation process.