French Drain for Septic Tank – What you need to Know?

Not every locality has a sewage system maintained by the municipality. Recently developed areas will not have access to the main sewage line and they must suffice themselves with a properly built septic system.

A septic tank is like a miniature treatment plant that helps to decompose household wastes. While the solid wastes settle down in the tank, the wastewater flows out of the tank to a drain field. But is it possible to make this drain field into a French drain?

Let us discuss the possibilities of using a French drain along with the septic tank of your house.

French Drain for Septic Tank

You can use a French drain to prevent excess water from flowing into the septic tank. Also, if your septic tank has low capacity and the wastewater load is high, you can use a French drain to remove the excess water.

For example, when there is unexpected rainfall or heavy usage of household toilets, the septic system may flood and cause the sludge or solids to flow out. With a French drain, you can remove this excess water away from the septic tank and prevent the overflow of solid wastes and sludge.

To understand the use of a French drain for a septic tank, you must know how a septic tank works.

Working of Septic System

If you look inside a septic system, in the topmost layer you can find the oily layer of scum and the next layer is the liquid wastewater, and finally a layer of sedimented sludge.

The wastes from the household flow into the septic tank and the solids get sedimented at the bottom. The water present in between the scum and sludge gets filled and flows out of the tank through an outlet.

This outlet is a pipe that leads to the soil which absorbs the water over time. Usually, this pipe is small and doesn’t extend over a considerable length.

This is the major drawback in a drain field of a septic tank. When there is a sudden flow of water, the tank cannot handle the load and starts to overflow out of the drain field. Sometimes you can even find the toilet drains to have reverse flow from the tank.

So, you may find the sludge and scum to overflow inside and outside of your home which ruins your household. This is where a French drain would be very helpful.

How can You Use a French Drain for a Septic Tank?

If you are in an area with heavy rainfall, it is best to install a French drain to remove the excess water that may eventually get to the septic tank. If the area near the septic tank will get flooded with rain, then you must use a French drain to remove it. You can find the procedure to install a French drain here.

But if you are going to connect a French drain to your septic system outlet, then you should follow these guidelines to avoid any kind of mistakes:

• When you are laying a French drain for a septic tank outlet, try to use a large pipe to promote the easy flow of the wastewater.
• Try to extend the drain as long as possible to provide a large space for water percolation.
• Make sure to lay the pipe tapered gradually to avoid water retention in the pipe.
• Make slightly larger holes in the PVC pipe to allow tiny sludge particles to sediment and decompose in the soil below.
• The drain doesn’t have to be connected to any outlet and you can leave it open.
• If you have an existing French drain, connect the septic tank outlet slightly further away or lay a new line entirely.

These are the things you should keep in mind before laying a French drain for a septic tank.

What are the Disadvantages of Using a French Drain for the Septic Tank?

Although French drains are an effective way to combat septic tank overflows, there are some drawbacks to using them specifically for sewages. They are:

• French drain has very small holes in the pipe which may get clogged by the sludge particles that may flow with the wastewater.
• The wastewater will contain some sort of slurry which may sediment in the pipe over time.
• Normal French drains laid for rainwater drainage can last more than 40 years. But the French drain used for a septic tank can last only very few years.
• You cannot connect this septic tank drain to stormwater drainage.

Conclusion

French drains for septic tanks can be a better choice to avoid the overflow of wastewater from the system. You can easily remove excess water flowing inside or outside the septic tank. But one must make sure to lay the drain in a proper manner by following the right procedure. This can avoid the stagnation of wastewater in the pipeline.