Pumping Should Be Required for Thorough System Inspections

When a local municipality moves to eliminate mandatory pumpouts for lake home onsite inspections, the Answer Man steps in with solid advice.

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About a year ago I wrote about troubleshooting some problems with system backups and mentioned it was important to periodically inspect and pump out septic tanks to prevent problems in the future. This prompted a comment from a reader, a leader of a lake association, that highlighted the group in a process of inspecting all systems near the lake looking for malfunctioning or failing systems.

The program included a mandatory, concurrent pumpout during the inspection. The reader stated, “We, like you, believe that this is the best approach for detection of improperly functioning septic systems. Our local municipal council, with advice from the chief building inspector, has recommended to drop the mandatory pumpout concurrent with the inspection for the remainder of the program. Strangely, a pumpout is required, but not at the time of the inspection. There has been no adequate rationale provided to date for this recommendation.”

This is apparently a one-time, across the board program to identify systems that need fixing or replacement. As I have explained in the past, this is one approach to inspections. Others are compliance inspections (the inspection referred to could be a compliance inspection as well) to make sure all system components are up to date; inspections at time of installation to make sure everything is up to current regulations; and inspections at time of real estate sales. While the purposes of these inspections are somewhat different, the actual inspection activities should not be different.

Any inspection of an operating system should involve opening the tank observing the contents, evaluating structural soundness, watertightness, condition of the inlet and outlet baffles along with the piping in and out of the tank.


If the tank is operating as it should, there will be three distinct levels observed. There are floatable solids (scum); a relatively clear zone where effluent is drawn through the outlet baffle and sent to the next treatment component; a sludge layer of settleable solids. If there are not three layers, the reason why should be determined and corrected to prevent solids from plugging the outlet or moving out of the tank. 

As an aside, many states and municipalities have requirements to evaluate sludge and scum accumulations periodically, and when they reach 25% to 30% of settleable area, pumping the tank is required. My town requires inspection every three years and a mandatory pump every six years regardless of the levels. As for me, I always have them pump the tank regardless; I look at it as my own little insurance policy to prevent problems down the road.

Structural soundness and watertightness can best be determined by pumping the tank. Before pumping, the liquid level should be observed. It should be at the invert of the outlet. If it is below, it means effluent is escaping the tank through cracks or holes. If the liquid level is above the invert, some type of blockage is occurring. The interior of the tank should be inspected for any deterioration, such as pitting or spalling of the concrete and any other cracks or holes. All tanks — no matter the material — should be investigated for the presence of roots, which indicate the presence of cracks or problems with the joints present in the tank. 


Baffles and screens in the tank should be evaluated. There should be baffles at both the inlet and the outlet, contrary to other comments I receive from time to time. The inlet baffle directs the flow down into the tank, preventing short-circuiting of effluent directly to the outlet. This provides the settling time for the larger solids. For this reason, sludge depth should be thickest under the inlet baffle. The bottom of the outlet baffle should be in the clear water zone of the tank.

Baffles should be evaluated for proper position, secured well to the piping or tank wall, clear of solids and not deteriorating. If there is evidence of corrosion, particularly at the outlet, the tank should be tested for proper venting to keep corrosive gases from accumulating. The piping into and out of the tank should be inspected to see that it is not cocked at an angle due to tank or piping settling. If the piping in either location is not correctly seated, blockages can occur, causing backups.

Septic tanks now usually have effluent screens at the outlet. They should be removed, cleaned, evaluated for any cracks or irregularities and replaced if necessary. An important note — the effluent screen should not

be removed for inspection until the tank has been pumped at least below the outlet baffle to prevent solids from moving out of the tank.

Specific to the reader’s comments, an inspection to evaluate how well all the systems around the lake are working requires pumping out the tank. Without removing the tank’s contents, structural integrity cannot be assured and critical information about whether the system may experience problems in the drainfield or in the future will be lacking. 

If baffles are out of place or at risk of deterioration, these problems can be fixed before they cause problems in the drainfield due to plugging and surfacing effluent or backups into the house. This type of community-wide inspection program is an opportunity to set all the systems up in the area for long-term trouble-free operation. 


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