How to measure septic tank scum and sludge thickness - USDA DJF Tools to Measure Septic Tank Scum & Sludge Levels

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Tools for measuring septic tank scum / sludge:

This article explains the necessity of measuring the thickness of the floating scum layer in a septic tank and of measuring the thickness of the settled scum layer in a septic tank as well. We include descriptions of how to make septic sludge and scum measuring tools and how to use them.

Whether your system is a conventional septic tank and drain field, an above ground septic system, or even a holding tank, pumping and inspecting the septic tank is a critical septic tank maintenance and septic system maintenance chore. Septic tank pumping pumping frequency guidance is provided in a table at our website (see links abovet.)

Just before the septic tank is pumped, measurements of the scum layer and sludge layer tell you the condition of the system.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

USDA / US FPS design for Septic Tank Sludge & Scum Measuring Tube

Septic tank scum and sludge measuring tube - USDA - DJF Here we describe how to make a simple tube for measuring scum & sludge level in a septic tank. We also describe electronic septic tank scum and sludge level monitoring - a sensor also used for grease traps.

Why Scum & Sludge Layers Measured Before the Septic Tank is Pumped

These septic tank sludge/scum measurements, made or at least roughly estimated by the septic pumping contractor are made before actually pumping or cleaning the septic septic tank.

The scum layer thickness and sludge layer thickness provide key information that permits the home owner to know:

1) whether or not the septic tank is being pumped often enough, and

2) whether or not there is evidence that the septic fields have been damaged by having not pumped the tank soon enough.

The USDA/FPS sketch above shows a tube and rubber ball design that can be used for measuring both the septic tank floating scum layer, and the septic tank bottom sludge layer thickness.

How to measure septic tank scum and sludge thickness - USDA DJFThe tube can be constructed using acrylic plastic (as shown) or a PVC plastic pipe (more readily available. All you need is a rubber ball that is a bit larger than the inside diameter of the pipe, some string, a washer, cotter pin or wire, and a scrap of wood for a handle.

The length of pipe needs to be long enough to safely reach the tank bottom without you having to lean over or reach into the tank, but short enough to be easy to handle.

Eight feet should be plenty. If you find that your septic tank bottom is just four or five feet below the ground surface you can later cut some excess off of the pipe.

Shown here is a USDA sketch showing how this measuring tube can easily measure both the floating scum layer in the septic tank and the bottom sludge layer thickness in the tank.

At left is an illustration showing how the pipe and rubber ball measuring system is used to measure septic tank scum layer and bottom sludge layer.

Watch out: opening, leaning over, or falling into a septic tank is dangerous and can be fatal.

Do not work alone. See the safety warnings at SEPTIC SYSTEM SAFETY WARNINGS.

How to Measure Septic Tank Scum & Sludge Layers

Details of just how to measure the sludge and scum layer thickness are given in this separate article: MEASURE SCUM & SLUDGE.

A description of normal and abnormal scum and sludge layer thicknesses in the septic tank and an explanation of what abnormal conditions mean is at SEPTIC TANK LEVELS of SEWAGE.

After the septic tank has been emptied your contractor may examine the interior of the septic tank for signs of trouble.

Our photograph illustrates a simple but effective septic tank inspection tool: an extension pole that sports an adjustable mirror and a bright flashlight.

Photograph of a septic tank interior inspection tool using a pole, mirror, and flashlight

Details of what to look for when the septic tank has been emptied are found at INSPECT the SEPTIC TANK AFTER PUMPING

Electronic Monitors for Septic Tank Scum & Sludge Levels

Below at References we also describe an electronic septic tank monitor or grease trap monitor from Worldstone.

Septic tank monitor These devices can track sludge, scum, or grease levels in order to best schedule septic tank pumping or grease trap cleaning. This product is suitable for commercial installations and possibly for some residential septic tank systems.

According to the company, "Data from monitors can help establish appropriate service intervals, and document maintenance for regulatory compliance. Alarm features can help detect abnormal conditions and prevent costly backups."The company also produces an oil tank level monitor.

Thanks to reader Robert Shirley for this tip.

OPINION - DF: this product is a great idea for commercial installations or problem septic installations. Substituting actual septic tank scum layer thickness or scum level thickness data for the septic tank pumping schedule table above may allow the tank to be opened and pumped less often - saving some money.

Watch out: But don't forget that regular opening and inspection of the septic tank, such as happens when the septic tank is to be pumped out or "cleaned", gives an additional opportunity to check for other septic system problems that could be leading to a costly failure, but that don't directly concern the septic tank sludge or scum layer thickness.

Examples include the discovery of lost or damaged septic tank baffles, septic tanks leaks that allow ground water to flood the septic system, or septic tank leaks out of the tank.

Below at in the form of individual detailed articles are the Steps in Septic Tank Cleaning Procedure in the order that they should be performed


Continue reading at PUMPER TRUCK OPERATION PROCEDURE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Or see INSPECT the SEPTIC TANK AFTER PUMPING where we describe septic tank inspection mirrors, cameras & other tools

Or see these

Septic Tank Inspection Articles

Suggested citation for this web page

TOOLS for MEASURING SCUM & SLUDGE at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

HTML Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman