How To Diagram and Layout a Yard Drainage System

Step 3

Please first read Steps 1 and 2 of our Drainage Guide

In Step 3 you will find information on:

  • How to diagram and layout your drainage system
  • Drywell and French drain installation
  • Perforated plastic pipe and drainage tile


In Step 1 you learned "How To Discover Your Water Drainage Problems". Then in Step 2 you learned "How To Design a Drainage System".

Now it is time to combine all the pieces of drainage information you have learned, and create a solution. The goal here is to solve your drainage problems with as little digging, and as little cost, as possible. To achieve that goal you will design and diagram a COMPLETE drainage plan, but only install one or two parts at a time to see if your drainage problems can be solved with a PARTIAL drainage system.

First get out your original rainy day sketch and re-draw it nicely on a clean paper. Also refresh yourself on the information in Step 2. The additional links in the following text will take you to additional instructions and tips on how to build or install the drainage features.

The example below to the right will show you how to produce a yard drainage diagram

We will use this example of a house on a corner lot that has one drainage problem in the side yard and a separate drainage issue in the front yard by the sidewalk.
See the diagram below...

In our sketch of this house the Lake Downspout type issues are labeled with a 1, the Soggy Lawn Swamp areas are labeled with a 2, and the Rainy Rivers created as the lawn swamps overflowed are labeled with a 3 anywhere they gather and flow. Note that there was an area next to the driveway where rain water flowing off the drive quickly builds up and that is labeled as a 1 also.

In this example, each 1 is connected by a line to any 2 that it feeds, and each 2 is connected by line to any 3 that it feeds. This diagram shows the flow of the rain water.

drawing of the drainage problem locations


The next diagram shows what the drainage pipe layout would be for a COMPLETE drain installation

Notice that the locations of the drain lines have been shifted away from the trees to avoid the root areas. Also notice how all the pipe runs are straight and how connecting pipes intersect at either 90 or 45 degree angles. This is because there are only 90 and 45 degree connectors available for rigid plastic drainage pipe.
See the diagram below...

Click the links to read why I do NOT recommend the flexible corrugated perforated plastic drainage pipe and also be sure to read why some T connections shown here use 45 degree connectors.

drawing of complete drainage plan


Remember that although this shows a complete drainage system diagram, the goal for anyone using their own muscle and money is to install as little of the system as will solve the drainage problem.


The plan for the FIRST portion of the drainage system we will install

The most critical problem in the above drainage diagrams is the water that builds up right next to the foundation in the front yard. When checking the slope of the ground in this area we find that it is too flat and therefore needs to be built up to get the water to drain away from the house. The second noticeable item is the long length of drain needed to get from the wet Area 2 in the side yard clear out to the dry area.

To minimize our digging and material costs, we will first try two smaller drainage projects...
See the diagram below...

FIRST: In the side yard, we will only install half of the French drain system and a pair of small drywells to see if it corrects the drainage problem. TIP: the leftover soil from this can be used for the second step.

SECOND: In the front yard, we will fix the foundation ground slope problem. We will also try installing a few independent drywells along the path of the proposed French drain to see if they will handle the Soggy Lawn Swamp problems.

diagram of first drainage attempt


Although it can't be seen in this picture, the drain pipes servicing the area 1 locations in the side yard include short vertical pipes that rise straight up from underground piping to accept the downspout and the surface drain for the Area 1 next to the driveway. These vertical pipes also allow access to the drainage system if a Roto-Rooter type cleaning is ever needed.

Click here to go to Step 4 - "Results from the Partial Drainage System" - to see how the partial drainage system works out.