Get Ready to Address the Scarcity of H2O

With population growth in desert regions and aquifers being depleted nationwide, will your future onsite systems incorporate a water reuse component?
Get Ready to Address the Scarcity of H2O
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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As I’ve mentioned in past columns, I have spent a lot of time in the desert Southwest. Some say this is just to escape the snow and cold of Minnesota and Wisconsin, but I actually have family ties in Arizona and did graduate work at the University of Arizona in Tucson.

I have developed an appreciation for the unique environments found throughout the Southwest and the impact limited water resources has on its residents. The small community where my mother lives gets its water supply from a private well more than 600 feet deep within an aquifer where the water level continues to drop despite conservation efforts.

So what does that have to do with our industry?

This type of situation is not confined to the Southwest; water scarcity receives a lot of attention because of the extended drought period currently being experienced. Even Minnesota — a water-rich state at the headwaters of three major river systems — has areas where aquifers are being depleted. The growing concern over water means we are going to be challenged as an industry about how we plan to incorporate reuse and aquifer recharge into decentralized wastewater treatment systems.


The concept of using treated wastewater for irrigation and aquifer recharge is not a new idea. In California, treated water has been used to irrigate open park areas since the early 1900s and used to irrigate golf courses since the mid-1900s.

We also see reuse in terms of recycling water within buildings for use in flushing toilets combined with waste separation to conserve water. As the need for water conservation increases, you will see this in your communities if it is not already happening. Even in Minnesota, municipal buildings around the Twin Cities have these features built into them.

To this point, most examples of reuse have involved municipal treatment plants or collections systems involving millions of gallons. This involves large expenditures of energy and the need for significant infrastructure (pipes, pumps, etc.), which makes it somewhat inefficient and does nothing to provide advantages for the more than 60 million Americans served by decentralized systems. These systems do not move large quantities of water and reuse systems could operate at a much lower cost.

There are many ways decentralized systems could realistically present water reuse opportunities. Serving single residences, clusters or small communities, they are smaller in size, scope and operation costs. The collection, treatment and reuse occurs near the point of generation. Treated water could be used to generate energy locally or for horticultural or agricultural purposes as well as contributing water for aquifer recharge.


So back to my mom’s community. It was designed in the early 1960s by renowned architect Bennie Gonzales, a disciple of Frank Lloyd Wright. The landscaping and housing units were to emulate a Mediterranean village with a Southwest flair. It involved open turf grass spaces and a large variety of plantings from both Arizona as well as non-native species. To lose the turf grass and plantings would destroy the appearance and appeal of the community. Of course, there is resistance to move to desert landscaping to conserve water.

This is where our industry and reuse comes into the picture. Ongoing research is looking at subsurface drip irrigation using treated effluent for turf grass areas. In the grand scheme of things it does a couple of things. It reuses the water on site, can be managed locally, uses the nutrients in the wastewater to benefit the plants, and since it is applied, becomes part of the treatment process to make sure water that moves downward to replenish the aquifer does not carry unwanted contaminants.

What does this type of system look like and what is involved? Researchers at the University of New Mexico are evaluating a system that uses a membrane bioreactor (MBR), a relatively new technology for our industry, in combination with a sequencing batch reactor aerobic treatment system. Some of the problems with simply using aerobic treatment units to provide the additional treatment common for drip applications are the variable flow quantities and quality encountered day to day in onsite systems.


This type of system uses a combination of nitrification and denitrification processes so specific qualities of effluent can be produced over a few days. This can occur under rapidly changing conditions due to different household use patterns that create problems for some technologies. This also means different water qualities can be obtained through management that fits particular plant needs — whether turf grass, trees or shrubs — based on the soil types at the site.

The final treatment and dispersal area is then a subsurface drip irrigation system like those we currently employ. Putting in a subsurface system helps allay public concerns about wastewater at the surface, reduces losses of water through evaporation and promotes movement of water through the soil for aquifer recharge.

Whether this is a long-term solution or not for my example remains to be seen. Perhaps additional conservation will be required, but the system takes advantage of the decentralized wastewater treatment approach. A question for our industry going forward: Are we prepared and knowledgeable enough about the installation, operation, maintenance and management of systems like this so we can be involved in the future? If not, now is the time to obtain the education and the skills necessary to play a part in innovative solutions to our wastewater and water use problems.


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