Drainage System Design: 3 Mistakes to Avoid

French drain pipe

Inadequate drainage, as any homeowner can tell you, will cause soggy lawns, muddy gardens, and flooded yards. These problems can often be corrected with a good drainage system design. You can avoid three common mistakes by designing and installing the right drainage system.

1. Creating the System Without Knowing Excess Water Source

Drainage problems are usually caused by excessive water. Sometimes water pools up from continuous rain or melting snow, but it can also come from a high water table, a broken underground irrigation pipe, or a leaky water pipe. Before spending time and cost associated with the design and construction of a drainage system, you should determine the source of your excessive water. If you can stop its flow, you may find that there is no need to construct a drainage system.

If excessive drainage water, rainwater, or an underground spring, for example, cannot be stopped, the only solution may be to design and build a drainage system.

2. Overlooking Soil Composition

person holding soil in hands

Soil composed mostly of clay is the worst in allowing water to drain. However, don't make the mistake of assuming you can't work with this kind of soil. You can often change its composition by mixing it with compost, gypsum, or sand. Just spread the added topsoil and use a garden tiller to mix it in. Another method is to add sand over the top of your clay soil and get better drainage without tilling the soil.

3. Creating the Wrong Kind of Drainage System

If it is not possible for you to solve your drainage problem by changing soil composition or by stopping the flow of excess water, your last option may be to install a drainage system.

Based on the materials you have to work with, the slope of your property, and available equipment, there are three types of drainage systems from which you can choose. But if you choose the wrong one you could find your system clogged with mud from drainage water, or water that is draining too slow. You need to know before installing your system, which one will work best for you.

  1. Open Ditch: An open ditch will drain fast and is not as likely to become clogged with mud, but you may not want an open ditch on your property.
  2. Gravel Trench: If you fill your ditch with gravel and cover it with topsoil or grass, your drain will be hidden and the water will still drain at a good rate. This type of drain is more likely to become clogged with dirt and mud.
  3. Drainage Pipe: In burying a drainage pipe into the trench, your water will drain faster, you can avoid having an open ditch and the pipe is less likely to become clogged (if it's 10 inches in diameter or larger). The cost of the pipe and the extra work it will take to seal its joints will be greater.

Most of a homeowner's drainage problems can be resolved by one of the three methods covered here.