Title of Question:
French Drain
Name:Bill City: South Jersey
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| Question: Do I need to bring the low end of the French Drain back up to the surface or keep it below ground? If below ground, how low below the surface should the low point go, so the water stays below ground and doesn't saturate back up to the surface? |
Post Your Answer To The Question Above:
| Answer: Hi Bill! You do not want to bring the French drain back to the surface. It is not necessary, and moreover, doing this will trap water in your French drain system, taking away its effectiveness at moving water. French drains work because water flows downward. If you angle the pipe back upward at the end, the water will not flow upward. It will stall out at the lowest part of the line. Because the water is stuck, the pipe will be full of water that it cannot get rid of. It cannot take on more water higher up the line because it is already full. Because the water cannot be drained away, it will stay in the soil, in effect canceling out the usefulness of your drain. When given a choice, water always moves downhill, and it also always moves from areas of lower pressure to higher pressure. Therefore, French drain systems can be installed quite shallowly. Bury your pipe around 24 inches down at the highest point, and then make sure that you have at least a 1/4 inch slope for every foot of pipe. The water is not going to flow upward to the surface when it has the option of running downward, and the gravel around the pipe attracts the water because of the relatively large space between the individual pebbles. |
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