Sample drainage plans are used in construction before the building is made so that the building has appropriate drainage and lines in place. The sample plan is a basic design for the building drainage and can alter or change as necessary. When preparing the drainage plan, every potential obstacle is considered and plans are drawn up for optimal performance. The original sample plan, which is a simple plan that shows directions and locations for the drains, is later made into blueprints for construction.

Analyze the drainage needs of the site. Drainage needs differ based on specific site location, the type of construction project, obstacles in the way and the needs of the construction project or building. Visit the site when it is raining to get an idea of how the water currently flows on the site. Make note of this on a rough drawing to incorporate into the sample drainage plan.

Draw up a diagram of the area that requires a drainage plan. This should include proposed buildings, streets and other items being built in the location. Draw the diagram to scale according to building specifications or land space.

Add drainage to the diagram. Drainage plans are as simple as drawn arrows showing where the drainage is installed and the direction that drainage flows. The drains are installed in ditches or underground, but the sample plan will show where it is located, what direction the drain travels, how many drains are in the area and whether it is a ditch or a drain. Drains are often solid lines while ditches are broken or dotted lines.

Adjust the plan as necessary. Make changes and adjustments to the plans after the original sample is drafted.