Best Pumping Practices

Did you know an industry standard procedure exists for septic tank pumping and cleaning? Do you have suggestions for updates or changes?

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Over the past few months, I've heard a variety of questions regarding pumping septic tanks and other sewage tanks. Also, some states have become more interested in requiring pumpers to take a class on vacuum truck operation and how to properly pump and clean septic tanks.

There is a set of performance standards for pumping and cleaning septic tanks. My apologies if I don't have the exact sequence, but I believe the idea for such a standard originated with the Pennsylvania Septage Management Association due to questions associated with their early inspection program for onsite systems.

Numerous states also saw a need for such a standard, and the National Association of Wastewater Transporters — now the National Association of Wastewater Technicians — answered the challenge to make it a national standard. Below are the elements of the standard with some additional explanation. I'm interested to hear what others in the industry think of the practices and if additional items should be added. The present standard has been in place for a decade.


At all times, the technician's safety, as well as protection of the environment and the customer's property, shall receive the highest priority. Generally, the tanks should not be entered as they are a hazardous environment. If entry is required, appropriate confined space entry procedures consistent with the Occupational Safety and Health Administration requirements should be employed. This seems like common sense; but it also seems we read about someone entering a tank and dying every year. Do not do it!

Accessing tanks

Tanks shall only be pumped from/through the manhole/access port. Tanks shall not be pumped from/through the observation port. If customers insist on the tank being cleaned through any opening other than the access manhole, they shall be required to sign a waiver acknowledging that they have been informed of the proper procedure and the reasons associated with that procedure. No liquids or solids are to be discharged into/through the outlet pipe.

Some tanks have more than one access manhole to a compartment. They all should be opened and used when cleaning the tank. The no-discharge practice is even more important these days with the widespread use of effluent screens. One of the newer aspects of cleaning the tanks includes cleaning these devices. It is important to take the tank level down below the outlet when the screen is removed to prevent solids from moving downstream.

Tank cleaning

The liquid, solid and semi-solid material in a treatment tank is removed by a vacuum or centrifugal pump fitted with a hose, delivering the material to a truck-mounted, sealed tank. Cleaning procedures should include agitating all solids, but only after lowering the liquid level to 12 inches below the outlet. This is necessary to ensure solids won't escape the treatment tank for the drainfield.

Agitation methods vary, and may include alternate pumping and backflushing, forcing air into the tank, or mechanical stirring. When backflushing or injecting air, care shall be taken not to fill/refill the tank to a level greater than 12 inches below the elevation of the outlet pipe. Tanks shall be deemed to be clean when all organic solids are removed and the total average liquid depth remaining in the tank is between 1 and 3 inches.

When using equipment designed to remove the material, separate the solids and the liquids, and return the liquids to the tank (some jurisdictions don't allow this technology), the following conditions must be met: The liquid discharged to the treatment tank must have a TSS of 400 ppm or less, and the volume of returned liquid must be less than the volume of the treatment tank (measured to the invert of the overflow pipe) so as not to have liquid overflow into the absorption area.

Standard services

Every pump-out shall include a visual inspection of the tank interior. The inspection shall note the presence of baffles and their condition, as well as the physical condition of the treatment tank. Observations of any unusual conditions such as high or low liquid level, run-back from the absorption area, defective or broken components, missing or broken observation port(s), lush vegetation, and/or sewage overflows should be reported to the customer.

It is advisable to observe sewage flows from the building into the tank. Corrective action for obstructions should be recommended. Any unsatisfactory conditions should be noted on the sales slip or receipt. Future maintenance frequency should be communicated to the customer at the time of service. Publications through U.S. Environmental Protection Agency and various universities provide a way to estimate maintenance needs. One service strategy is to provide one of these "homeowner guides" to your clients to explain ways they improve or hurt the operation and longevity of the onsite system.


NAWT has no position on the use of chemical or bacterial additives for treatment tanks as it believes research is inconclusive. This can be a controversial topic and there is disagreement among pumpers. My guidance is that if you are thinking about using additives, start with situations where you know current operating levels, have some control over the maintenance frequency, and can monitor performance to draw your own conclusions until definitive studies are available.

Local, state and federal laws and regulations

At all times, and in all phases of operations, pumping businesses and equipment operators shall comply with all laws and regulations regarding the activities associated with onsite wastewater system maintenance and disposal of materials removed. Hopefully it's common sense to follow state and local requirements.


Where the permitting authority requires documentation of pump-out and tank and site conditions, the pumper shall not be prevented by the customer from complying with those requirements. A copy of the report sent to the authority shall also be provided to the customer.


While NAWT has adopted this Code of Practice as a recommended standard, it is the responsibility of the contractor to give ethical and professional services to its customers and the responsibility of the customer to assure quality control. I will be interested to hear back about how many of you knew there was such a practice standard and what should be added or changed.


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