Complex Drainage System
A Complex Drainage System has two or more “Intakes.”
An intake is a Drain of some kind where water is taken into a Drainpipe.
A Surface Drain connected to a French Drain with Gutter Downspouts connected as well is a Complex Drainage System.
French Drain Connected to a Channel Drain across the Driveway
Above is a picture of a French Drain connected to a Channel Drain which connects to a transition pipe. The Transition Pipe takes the water downhill to the exit.
Transition Drainpipe Installation Running Out Through the Curb
Simply Put, a Complex Drainage System has several water sources that comes from different kinds or drains or gutter connections.
Installing Surface Drains
The Complex Drainage System shown above has three Surface Drains connected to one Transition Pipe. It can be one type of drain or several.
Many times, a gutter downspout is connected to a Complex Drainage system too.
Gutter Connected to Drainage System
Complex Drainage System Problem
If you connect too many Drains (Intakes) to a Transition Pipe it will become overwhelmed. A hard rain will cause water to back up and can even cause Vapor Lock which will slow down the water even more. You will definitely experience poor performance.
A Good General Rule.
Most Transition Pipes are 4 inch in diameter. Don’t connect more than 3 Intakes (Drains or Gutter Downspouts) to a 4-inch pipe. If more than 3 intakes need to be connected to the transition pipe, then add a second 4-inch Transition Pipe or use a 6-inch Transition Pipe instead of two 4-inch pipes.
Multiple Drainpipes
The Picture above shows two 6-inch pipes and Three 4-inch pipes. They are all Transition Pipes taking a lot of water to the exit.
Transition Pipes can be ADS which are Black and Flexible or PVC which are white or green and are very rigid.
ADS Transition Pipe is much easier to work with.
