Use a measuring tape or other accurate measuring device. Many irrigation system problems are traced back to inaccurate measurement of the area to be irrigated. Go ahead and round off numbers to the nearest foot. But keep in mind that a minor deviation of a couple of feet can result in dry spots!

Draw the area to be irrigated to scale on a piece of graph paper as you measure it. Use a scale of 1 square = 1 foot, or 1 square = 5 feet if needed. Drawing as you go allows you to quickly catch errors. For instance, say you measure the perimeter of the yard. Eventually you get back to the point where you started, but you find that the lines drawn on your paper don’t meet like they should! Now you know there is an error in one of the measurements, and you can go back and find it quickly, while it’s all still fresh in your mind.

If there is a building adjoining the irrigated area, start by measuring the building’s perimeter. Most buildings are built with square corners and straight sides, which gives you a good, accurate base for the rest of your measurements.

Use the straight sides of the building as a guide for establishing the perimeter of the area to be irrigated. Measure in a straight line the distance from each corner of the building to the edge of the irrigated area or property. (Locations to measure are shown in red on the sample drawing below.) Use the straight edge of the building to line up your measurements. Now you can draw in the property lines on your graph paper using these measurements. Double check everything by measuring the length of each property line. It should match exactly what you have drawn. Don’t be surprised if you find that an area you thought was “rectangular” is actually lopsided like the one in the sample drawing! Most pieces of property aren’t perfect rectangles.

The final step is to draw in the other items that are present in the area. For example, if this is your house, you would need to show the edges of lawns, tree locations, the location of your pool house, the servant’s quarters, etc. (Okay, I realize most people with servant’s quarters don’t design their own irrigation systems.) With the building and property lines drawn it is easy to use the grid on your graph paper to establish the locations of these items.