How to Draw a Plumbing Plan of Your House, Online

What a plumbing plan is for

A plumbing plan is a floor plan with the water system drawn on it: the supply lines that bring cold and hot water to each fixture, and the drains that take the used water away. It answers practical questions. How far is the new bathroom from the water heater? Can the washer move to the other side of the wall? Where does the drain from the second floor go down?

It helps in three ways. It makes a conversation with a plumber precise, since you point at a drawing rather than describe a room. It lets you compare quotes on the same list of fixtures and runs. And it lets you move things on paper before anyone cuts into a wall or a floor, where changes are cheap.

General principles, and who decides the rest

These are habits of good practice, not rules. The details, such as the size of a pipe, the slope of a drain, the type of vent and the materials, are set by the plumbing code your jurisdiction has adopted, often a version of the International Plumbing Code or the Uniform Plumbing Code, with local changes. Your plumber knows it, and your building department enforces it.

• Keep the runs short. A fixture far from the water heater waits longer for hot water and wastes more while it waits, and a long drain gives more chances for a blockage.
• Group wet rooms where you can: a kitchen back to back with a bathroom or a laundry shares walls and risers, and costs less to pipe.
• Put the water heater near the points where hot water is used most.
• Drains need a downward slope and a vent to flow properly. Draw them with that in mind, and let your plumber set the slope and the venting.
• Keep the main shut-off valve and the water meter easy to reach, and know where they are before an emergency.
• Leave access to anything that may need work later: valves, cleanouts, the water heater.

Plan² does not size pipes, set slopes or check a plan against any code. If a figure matters, ask your plumber and your building department.

The method: from the fixtures to the pipes

1. Draw the structure first

   Draw the walls, the doors and the rooms, and name them. Pipes run through the walls and floors, so a correct base saves work later.

2. Switch to Water mode

   Open Layers and choose Water. A mode locks the other layers, so you can lay pipes without moving a wall, and you can still show or hide the layers you need to see.

3. Place the meter and the water heater

   Put the water meter where the supply enters the house, and the water heater where it stands or where you want it. They are the two starting points of the system.

4. Place the fixtures

   The library holds the sink, the toilet, the bathtub, the shower, the vanity and the washer, among others, and a septic tank for houses that have one. Pick a fixture, then click the plan. On a phone, place it with the viewfinder: drag the plan under the crosshair, then tap Place.

5. Draw the cold, hot and drain lines

   Plan² has three kinds of pipe: cold water, hot water and drain. Draw each as a run by tapping points from the source to the fixture, and finish the run. Give each pipe a diameter in the properties: Plan² records the value you type, and your plumber confirms it.

6. Join the floors with risers

   On a house with an upper floor or a basement, a riser joins two floors. Draw the pipe to the riser on one floor and carry on from it on the other, so the pipe length includes the climb.

7. Check the lengths

   Plan² totals the length of each pipe kind. Look for the long runs: a hot line of many feet to the far bathroom is a reason to move the water heater, or to add a second one.

8. Export with the legend

   Choose File, then Export…, pick a PNG or a PDF, the paper and the scale from 1:50 to 1:500, and select the networks to include: over the plan, under it, or apart, with one plan per network. Switch on the legend and measure to print the pipes and their lengths. The PDF is vector at true scale.

Common mistakes in a plumbing plan

• Drawing pipes before the walls and fixtures are right, and moving everything afterwards.
• Forgetting the drains, which take more room than the supply lines and need a downward slope.
• Putting the water heater at the far end of the house, so that hot water takes a long time to arrive.
• Forgetting the runs between floors, which are often the longest.
• Entering a pipe diameter as if it were a design value: Plan² does not size pipes, so the diameter is whatever you type, to be confirmed by your plumber.
• Treating the plan as a permit drawing, when the permit and the inspection go through your building department.

What Plan² does not do

Plan² does not size pipes, calculate flow or pressure, set the slope of a drain, design a vent or check a plan against the plumbing code. It does not draw sections, elevations or heights, which are coming. What it does is give you a clear drawing of the fixtures and the runs, with the lengths listed, which is the base your plumber needs to quote and to plan the work.