Gather the floor plan, fixture locations, and local plumbing code requirements
Mark all plumbing fixtures on the house layout
Identify the main water supply entry point
Identify the main drain, waste, and vent routes
Draw cold water supply lines from the main entry to each fixture
Draw hot water supply lines from the water heater to each hot-water fixture
Place the water heater on the diagram
Draw drain lines from each fixture to the main drain line
Add vent lines for each drain connection as required
Show pipe sizes for supply, drain, and vent lines
Label all fixtures, pipes, valves, and cleanouts
Mark shutoff valves at key locations
Indicate slope direction on drain lines
Separate cold water, hot water, drain, and vent lines with different line styles or colors
Include fixture symbols for sinks, toilets, showers, tubs, and appliances
Verify all connections meet code and layout requirements
Review the diagram for clarity and completeness
Finalize the drawing with a legend and title block