Finding New Uses for Abandoned Tanks

In drought-stricken regions, pumpers may find work repurposing old septic tanks for graywater recycling systems.
Finding New Uses for Abandoned Tanks
Jim Anderson, Ph.D., is an emeritus professor at the University of Minnesota Department of Soil, Water and Climate and recipient of the pumping industry’s Ralph Macchio Lifetime Achievement Award. Email Jim questions about septic system maintenance and operation at

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I spend a good deal of time working in the U.S. Southwest. There has been an ongoing drought spanning approximately a decade throughout the region. Although substantial El Niño rains and snows have helped, they have not alleviated the water shortages brought on by consumption and the drought conditions. As a result, efforts have been made to conserve water and reduce consumption or pumping from groundwater reserves, as well as encouraging measures to recharge groundwater.

As an example, communities promote the use of low-flow or no-water toilets and recycling of household graywater flows. Now another potential way to recycle or reuse part of a septic system has come into play. The suggestion is that if a septic tank or system is to be abandoned, the septic tank can be repurposed as part of a rainwater harvesting system. Rainwater collected in the tank can then be used to water landscape plants, reducing the use of potable water (or reused water for that matter) that had been pumped from deep aquifers.

A recent article on the topic suggested that having an abandoned septic tank cleaned and disinfected for reuse would cost $200 to $500 less than properly abandoning the tank. Now, this is coming from an area in California where the houses are being hooked up to a “big pipe” system, so not a positive necessarily for our industry but may result in work for some installers and septic service providers during the changeover, which is not a bad thing for them.

I believe this is a worthwhile approach. Water conservation initiatives should be considered, even in “water-rich” areas like the Midwest, where I live. However, there are a few factors conservation proponents and homeowners need to be aware of that may not be immediately obvious, and I believe our industry will run into more questions like this even in areas slated to be serviced by a wastewater treatment plant.


First, the authors of the article suggest that all of the tanks in the area could be used in this manner. As septic professionals, we all know this may not be the case depending on the age and quality of the tanks. Therefore, a first step is to inspect the tanks for structural soundness. And, given the large numbers of cesspools and seepage pits used in areas of the Southwest, we need to determine if these are actually tanks that could hold water.

Every year we hear about a person walking through their backyard and falling through the deteriorated tank cover of an improperly abandoned septic tank or seepage pit, sometimes with fatal consequences. It is key that a repurposed tank will be structurally sound, so no cracks, no deteriorated concrete and proper access points for future cleaning after the initial disinfection. If any of these negative conditions are present, the tank should not be used until or unless it can be repaired or upgraded.

If a septic tank drainfield system exists, the piping into and out of the septic tank must be removed, the connections completely removed, and trenches filled leading back to the house. There would be nothing worse than filling a tank with water and then having it find its way back to the residence through piping or trenches left behind. Similarly, any connections to a drainfield or seepage pit need to be permanently closed. Seepage pits should be properly abandoned by caving in the sides and filling cavities with granular material (soil, sand or rock) to prevent future collapse.

If the tank to be repurposed was used as a pump tank, all pumps and electrical connections should be removed and disposed of properly. Pump controls with mercury switches must be disposed of according to applicable regulations.

Any openings in the tank for electrical lines should be closed and sealed.

When decommissioning a drainfield, mound or at-grade system, human contact with materials should be avoided. Any part of a system that has been in contact with sewage should be considered contaminated material and handled accordingly. Any soil waste that has mixed with sewage would be considered septage and would fall under the Federal 503 regulations. So a record of custody would need to be maintained and agreements on the part of sewage treatment plants or landfills be obtained between the accepting facility and the service provider doing the work.

Contaminated piping, geotextile fabric, rock or other trench media should be dried and disposed of in a mixed municipal solid waste landfill or other designated disposal site.


Going forward I expect our industry to be faced with similar questions and challenges. It means the job will continue to evolve and change, and we need to keep our minds open to new approaches and perhaps other service niches we can fill.


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