Plumbing plan: cold water, hot water and drainage

What a plumbing plan is for

A plumbing plan is a floor plan with the water installation added. It shows the water meter, the water heater, the fixtures such as the sink, the toilet, the bath and the washing machine, and the pipes: cold water, hot water and drainage. It lets you see the whole path, from the street to the tap and from the plug to the sewer.

It is useful at three moments. When you plan a bathroom or a kitchen, it shows how long the new pipes will be and whether the fixtures can sit where you want them. When you ask for quotes, it gives the plumbers the same facts to price. And later, when something leaks, it is the record of where the pipes run.

A plan drawn by you is a base for discussion with a plumber. The plumber and the local code decide what is installed.

Principles of good practice, not rules

Some principles are general good practice, and a plan helps you apply them. They are not regulations, and they do not replace what your plumber and the local code decide.

• Keep the pipes short. A long run of hot water takes time to arrive and loses heat, and a long run costs more.
• Group the wet rooms. A kitchen, a laundry and a bathroom back to back share their pipes and drains.
• Place the water heater near the points where hot water is used the most.
• Remember that a drain needs a fall, so it must be able to run downhill, and that a drain needs ventilation. Ask the plumber how the slope and the ventilation work in your case.
• Keep the shut-off valve and the meter accessible. Anyone should be able to cut the water quickly.
• Think about the winter. A pipe in an unheated space or an outside wall can freeze, so the plumber will tell you how to protect it.
• Leave access to the connections that may leak, and do not bury them behind fixed finishes.

What to prepare before you draw

• The plan of the structure, with the walls, the doors and the windows.
• The position of the water meter and of the shut-off valve, and the place where the supply enters the house.
• The position of the water heater, or the place where it will go.
• A list of the fixtures, room by room: sink, basin, shower, bath, toilet, washing machine, dishwasher.
• The route of the drain to the sewer, or the position of the septic tank if there is no mains drainage.
• Photos of what is already there, if you are renovating.

Drawing the plumbing plan in Plan², step by step

1. Draw the structure

   Draw the walls, the doors and the windows first. The pipes will rest on this plan, so check the dimensions before you go on.

2. Switch to Water mode

   Open the Layers button and pick Water. The mode offers only the plumbing tools and locks the other layers, so that a click does not move a wall. Hide the layers you do not need to keep the plan readable.

3. Place the meter and the water heater

   Put the water meter where the supply enters, and the water heater where it will stand. They are the two ends of the main supply, and the pipes are drawn from them.

4. Place the fixtures

   Pick the fixtures in the library and tap the plan to place them: the sink, the basin, the shower, the bath, the toilet and the washing machine. A septic tank is also available in the library if you have no mains drainage. On a phone, use the viewfinder to place each item under the crosshair.

5. Draw the pipes: cold, hot and drain

   Pick the type of pipe: cold water, hot water or drain. Tap each point of the run, then finish it from the island at the top of the canvas. Give each pipe a diameter in its properties: you type what your plumber specifies, because Plan² does not choose it.

6. Join the floors with risers

   If the house has an upper floor, add a floor first, then place a riser. A riser joins two floors and carries the pipes from one to the other. Check where it leads and what it carries.

7. Read the lengths and export

   Check the length of each pipe type. Then choose File, then Export…, pick the Plan, and include the water network: over the plan, under it, or apart, with one plan per network. Switch on the legend and the quantities, which list the pipes and their lengths. Choose PNG or PDF, the paper and the scale.

Common mistakes in a plumbing plan

• Drawing the pipes without the fixtures. A pipe that ends nowhere is hard to price.
• Forgetting the drain, which is often the hardest part to fit because it needs a fall.
• Putting the water heater far from the points of use, so that hot water takes a long time to arrive.
• Hiding the shut-off valve or the meter behind a cupboard or a wall.
• Mixing hot and cold in the drawing, so the plumber cannot tell them apart. Use the pipe types.
• Forgetting the risers when the house has several floors.
• Treating the diameters you typed as a design. They are what you copy from the plumber’s advice, not what Plan² calculated.

What Plan² does not do

Plan² does not size pipes. It does not work out the diameter from the flow, it does not check the slope of a drain, and it does not check your layout against plumbing regulations. It has no valves, no pumps and no diagrams of the water heater connection. Your plumber and the local code decide the diameters, the slopes, the ventilation and the materials.

What it gives you is a clear, measured plan: the equipment, the fixtures, the three kinds of pipe and their lengths, which you can print to scale, share and discuss. Keep the JSON file, and the plan stays editable.