Posted by Dennis Showers, owner Showers Plumbing (formally Jiffy Jet Plumbing).

Septic Tanks: From The Expert

Part 2: Your septic tank and how it works:


I am going to talk about the second half of the septic system, lateral lines, starting with the bio mat filter that is being placed in the septic tank, on the “out” end of it.

This filter catches approximately 95% of the little particles that are left in the second compartment of the septic tank and that helps keep the lateral-leach-absorption bed getting cleaner waste and wetter in its trenches. That will make the system last much longer.

The filter will have to be cleaned over time. The purpose of the lateral system is to let the water leach out in to the ground and dissipate into the ground as fast or faster than the waste water and solids are coming in to the septic tank; and to keep on working that way for years & years.

How to set up a septic system that will work for your home:
First find out the number of bed rooms that are in your home or home to be. Then look for a good place to install the laterals.

A soil evaluation will have to be made and this can be done in two basic ways:
One is called the perk test where a qualified person will dig three holes in the area that the laterals lines will be installed. The holes will be 3 feet deep and 4-6 inches in diameter. Next approximately 4-inches of gravel is poured into each hole. Next, water is poured in keeping it above one foot in depth for four hours. That saturates the ground like it will when the system is being used. Within 24 hours the actual test will be taken. The holes will have 6 inches of water poured in to them and they will be timed for 30 minutes and measured for depths of the water. This process is repeated 4 times to get a good average of how much and how fast the soil the will absorb the liquid coming out of the septic tank.

By using the number of bedrooms and the perk test results, we can figure up how many square ft and what kind of laterals to use.

Soil evaluation is another way of getting the figures needed regarding the amount of laterals required.  In this process is the evaluator digs a 5-foot-deep hole in the ground large enough to work in. He looks at the different layers and types of soils and matches them with soil charts that indicate different amounts of soil saturation per type of soil. The results are then figured off of that.

Lateral Trench Material:
There are several different types of material to use in your lateral trenches. 4-inch pipe with two rows of drilled holes in the bottom one third of it. This system has to have a minimum of 4-inches of washed gravel under it, around it and on top of it when used, but is a very efficient working system when installed correctly.

I will stop with just two types of material (but there are more choices). The second is a type of one half-moon infiltrator system. It comes in 4 or 5 foot section lengths and 2-3 foot widths. It doesn’t need gravel under it to work, but having gravel under and around it would make a superior draining system.

Read more:

Back to part 1 of this article on Septic Tanks

  • Septic Service by Showers Plumbing