Inspecting Your Septic Tank

• Measuring the Scum Level
• Measuring the Sludge Level
• Inspecting the Baffles
• A Typical Septic System
• Additional Information

This section will guide you through the steps of inspecting your septic system. To perform a complete inspection of the septic tank, the whole top must be uncovered. This is necessary for inspecting the baffles and for determining the levels of sludge and scum in your tank.

If you are only measuring the sludge and scum levels of the tank, the first compartment manhole cover and the cover over the crossover baffle must be uncovered and removed.

Measuring the Scum Level

This procedure is for determining the distance between the bottom of the scum layer and the bottom of the outlet baffle (distance "A" on typical septic system diagram below).

1.) Establish a convenient reference point, such as a stick laid on the ground across the hole or the top of the tank.

2.) Attach a 3 inch x 1 inch x 2 inch board at the bottom of a six-foot-long stick and lower it down through the outlet baffle (crossover baffle) of the first compartment. Hook the l x 2 board against the bottom lip of the baffle and make a pencil mark on the stick where it crosses the reference point. This stick is the baffle stick.

3.) Attach a six-inch-square board to the bottom of a second stick that is at least six feet long. This is the scum stick.

4.) From the manhole of the first compartment of the tank, work the stick through the scum layer. This is best accomplished by starting at a 45-degree angle and straightening the stick to 90 degrees once the board is through the scum layer.

5.) Raise the stick until you feel the bottom of the scum layer.

6.) Mark your stick at the reference point to indicate the bottom of the scum layer.

7.) Lay the baffle stick and scum stick side-by-side with the reference marks lined up together. The distance between the bottom of each stick represents the distance left between the bottom of the scum layer and the outlet baffle.

8.) If the distance between the two sticks is 3 inches or less, the tank needs to be pumped. If the top of the scum is within 1 inch of the top of the outlet baffle, or the top of the inside of the tank, the tank needs pumping.

9.) Lay the baffle stick aside for later comparison with the sludge level stick

Measuring the Sludge Level

This procedure is for determining the distance from the bottom of the outlet baffle to the top of the sludge layer (distance "B" on typical septic system diagram below).

1.) Tightly wrap three feet of a white rag or old toweling around the bottom of a stick at least six feet long and fasten it with tape or string. This is the sludge stick.

2.) Carefully lower the stick to the bottom of the first compartment. To avoid pushing it through the scum layer, lower the stick through the outlet baffle (crossover baffle) of the first compartment.

3.) Hold the stick in the tank for a few minutes to allow sludge particles to adhere to the towel. Mark the stick at the reference point to indicate the depth to the bottom of the tank.

4.) Carefully remove the stick and note a distinct dark stain on the towel representing the sludge layer.

5.) Lay the sludge stick and the baffle stick side-by-side with the reference marks lined up.

6.) Measure the distance between the bottom of the baffle stick and the top of the stain on the towel. This represents the distance between the top of the sludge layer and the bottom of the outlet baffle.

7.) If the distance is 12 inches or less, your tank needs to be pumped.

Inspecting the Baffles

1.) Remove the inspection covers over the inlet, outlet and crossover baffles. Inspect the baffles to ensure they're present and not severely corroded. If the baffles are concrete and molded into the rest of the tank, venting holes should be present and unobstructed.

2.) The inlet baffle should be unobstructed and the pipe well sealed to the tank.

3.) The outlet baffle should be unobstructed and the liquid level should be at the bottom of the pipe (not below the pipe or well above the bottom of the pipe). The pipe must be well sealed to the tank.

4.) The crossover baffle should also be free of obstruction.

A Typical Septic System

A Septic System With Measuring Sticks

Septic Tanks - Delzotto and Cascade Styles

Scum and Baffle Sticks

Additional Information

For more information on septic-system care, inspection and maintenance, call GullettSanitation Service Inc. at 513-734-2227 or Email  us at: CompanyWebmaster with questions or comments.
Last modified: April 18, 2008