A French drain, also called weeping tile or a trough filled with stone or gravel is basically a trench excavated in the ground with an inner layer composed of stone or crushed earth or containing a pervious pipe which redirects excess groundwater to another area. The innermost layer or crust of this trench is relatively dry while the outer layer, which is often moist, consists of fractured or slaggy materials. Drainage systems are generally made of PVC pipe, which can be insulated or made out of copper, brass or bronze. Another popular type of French drain is the type that imitates a river. These drains are commonly used for sewer and sewage line maintenance.

Drainage systems are categorized as primary or secondary drainage systems. As primary drainage systems, French drains are often installed where water accumulates quickly. This then becomes an issue when the water levels recede quickly and there is no outlet for the water. On the other hand, secondary drainage systems are installed where the rate of water accumulation is less than the rate at which water is draining.

The primary French drain can pose a problem if there is steep slope. If there is a slope that goes more than 50 feet from the property’s border, installing a French drain could become problematic. In addition, French drains are usually installed above the existing soil surface, which increases the amount of excavation needed. If excavation is required, this will add to the cost and may result in the drainage problem becoming worse.

A typical configuration for a French drain is to install it at least twelve inches below the existing soil surface. This means digging a hole that is at least twelve inches deep and then placing a one inch thick gravel inside the hole. Digging the gravel is not as difficult as it sounds. It only takes about two minutes and after careful leveling, you will have a perfectly level location to install your French drain.

In order for the French drain to be installed correctly, there are a few things to consider. First, the gravel must be placed on at least two feet level. Digging holes on or below the surface is not acceptable. Second, the gravel must be installed in a straight up path away from the existing basement walls. Digging into the basement could create problems later on.

Some basement owners prefer to have their French drains installed around the perimeter of their foundation. This is the best configuration for French drains. A basement that sits on concrete slab will not work. A concrete slab that slopes towards your house does not work either. Only gravel installed around the foundation will work.

One thing to keep in mind is that any gravel used to install your French drain should be three to four inches deep. This will ensure adequate water collection and proper water drainage. If you have a smaller French drain, such as a perforated pipe, then you can install the gravel deeper in the ground to collect more of the water running through the pipes. However, it’s important that you don’t go any deeper than the depth of the actual French drain.

If you are going to use gravel to install French drains, you will need to get some geotextile fabric. Geotextile fabric is a strong waterproof material that works great around French drains. The gravel comes out nice and even, similar to putting a layer of snow on top of the pipes. Just be sure to use plenty of water. Putting too much water on the gravel can cause it to be pulled off the French drain, creating pooling underneath the French drains. Once this happens, the pooling will start to decay and cause the drains to collapse.