If you are considering buying a home with a septic system, you may have been advised to invest in a proper inspection of the septic tank. It is important to have the home's septic tank inspected not only prior to purchasing the property, but also roughly every 1 to 3 years over the lifespan of the system. Since these systems allow scum and sludge to build up over time, it is important to check the levels in order to prevent clogged inlet or outlet baffles. Most systems require pumping every 3 to 5 years, depending on the size of the tank, household use and other factors. In order to understand how septic tanks are inspected, you must first have an idea of how these systems work.

How Does a Septic Tank Work?

Below is a general outline of the main components of any septic system:

- Sewer line - this is the main waste line leading from your home's plumbing to the septic tank

- Septic tank - this is the underground tank that receives and treats your home's waterwaster

- Leaching system - this is the drainage system that allows for waste effluent to be dispersed into the soil

The Actual Inspection

The method of inspection most commonly used is the "stick test." Below is a list of materials used in this type of inspection.

- 2 10-foot PVC pipes*

- 4 end caps*

- 1 90 degree elbow*

- PVC cement (blue cement used in rain and wet)

- 2 adapters, SxMPT, threaded*

- 1 coupler, threaded*

- 2 feet of white rag or old towel or old gym sock

- String or duct tape

- Pencil or waterproof marker

- Rubber gloves

- Disinfecting solution made of 1/4 cup bleach per gallon of water in a bucket

- Plastic bag for disposal of towel, rag/sock, gloves

The first step in the septic tank inspection is removal of the manhole cover in order to uncover the tank.

Second, the scum level is measured. This is done by creating a "scum stick" out of the PVC pipes, elbow and end caps. A board or stick is laid over the manhole and the scum stick is placed on it so that one end dips into the tank. The stick is then worked through to the top of the scum layer and marked. The stick is then worked through to the bottom of the scum layer and marked again. The distance between the marks is measured.

Third, the sludge level is measured.

First, a hole is made in the scum that reaches through to the top level of the sludge layer. A "sludge stick" of about 10 feet is made from PVC pipe and adapters. Cloth is wrapped around the bottom of the stick and fastened with duct tape or string. The sludge stick is then lowered into the septic tank carefully through the hole in the scum until the stick reaches the very top of the sludge layer. A mark is made on the sludge stick, then the stick is lowered all the way down to the bottom of the tank and marked again. The stick is held in place for five minutes to allow the sludge to create a stain on the cloth. The distance between the marks made on the stick represents the working depth of the tank, while the height of the stain on the cloth is known as the depth of the sludge layer.

Finally, the baffles are inspected. They are uncovered and inspected for corrosion and obstructed vent holes.

After the inspection is complete, proper cleanup and disinfection is carried out.