08/14/2026
What is that???
Scum... and it's a good thing to see in your septic tank!
A healthy septic tank will have three layers.
1. Scum - a floating top layer that is mainly made up of cooking fats, soap residue, grease, or food. Contains anything that floats in water.
2. Effluent - liquids which remain after the solids have settled to the bottom, and fats, oils, greases and floating waste have stayed at the top.
3. Sludge - the bottom layer of solids.
The top scum layer is a collection of many items that are unhealthy to be sent out to the system. They collect at the top and also allow bacteria living in the layer the opportunity to break down solids.
*Can you spot the soap suds at 1 o'clock in the picture? This is at the inlet of the tank. As it was cleaning day, soap suds were being pushed out into the scum layer, and the water was being pushed down into the effluent layer as noted above.