Drainage Systems Explained

In-ground drain systems are installed to catch excess water and allow it to drain away. There are two types of excess water: groundwater and surface water. 

Groundwater is water that collects below the surface. It can make your soil soggy, run into basements and crawlspaces, and create hydraulic pressure that can crack and push retaining walls. It is generally collected through french drains or foundation drains.

Surface water is water that pools or runs over the surface. It creates standing water, mud, and causes erosion. It is generally collected through grates and channel drains. These catch grates are placed in concrete on in the ground where water pools or flows. they catch the water and rout it underground through piping to prevent erosion and standing water.

There are two categories of drain systems: gravity flow and pump flow. 

Gravity flow drains use slope to direct the water to the desired area. A gravity flow system requires a lower area for the water to flow to. Not only must the pipe be sloped but the outlet must be a minimum of 1% lower than the high point of the drain, as measured in a straight line. Many lawns do not allow for this drop. If the surface grade does not allow for a 1% or greater drop, you will need a pump system. 

A pump system or sump system is simply a gravity drain system that runs into a low underground collection basin. When the collection basin fills up, the internal pump will turn on and pump the collected water to the desired area, usually a storm drain or swale.