What Is a Cluster System?

According to U.S. EPA: "A cluster (or community) decentralized wastewater treatment system is under some form of common ownership and collects wastewater from two or more dwellings or buildings. It conveys the wastewater to a treatment and dispersal system located on a suitable site near the dwellings or buildings. It is common to find cluster systems in places like rural subdivisions."

Image from U.S. Environmental Protection Agency

Cluster systems transport wastewater from a small number of homes (typically 2-10) via alternative sewers to either a conventional treatment plant or to a pretreatment facility followed by soil absorption of the effluent. Cluster systems can be financially sound, environmentally friendly solutions for small community wastewater problems, where conventional central treatment systems are not practical or affordable and where individual onsite systems are inappropriate because of site or soil limitations. 

The advantages of cluster systems are the lower average cost, flexibility in land use, less complex operation and maintenance for the community, and non-discharging, decentralized wastewater treatment systems can provide an environmentally sound alternative for small or disadvantaged communities.

The main disadvantage of cluster systems is the amount of operation and maintenance needed. While it is typically not complicated, alternative sewers have septic tanks that need to be inspected and pumped and mechanical parts and controls that use electricity. Since cluster systems are located onsite, workers are required to travel to individual homes or businesses. This type of decentralized wastewater system requires more frequent maintenance, which can be costly if anything is malfunctioning. 

Another key thing to keep in mind is that cluster systems require a somewhat complex organizational structure in order to make community decisions like fee collection and continuing education of homeowners about wastewater issues. The cooperation of homeowners using the cluster system is much more important than with municipal systems since smaller systems are less resilient and less tolerant of periodic large flows or larger than normal loadings of household chemicals than in large systems, where these peaks are averaged out over a very large user base.

A Case for Regionalization

Water and wastewater services are needed in every community in order to sustain it, but some communities need more assistance in order for their water utility to thrive. Many rural areas face challenges like meeting strict regulations while still providing affordable services to users. As technology becomes more sophisticated, the need to purchase new, expensive equipment becomes unavoidable for small utilities that often do not have the funding or resources needed. This is when regionalization can really benefit utilities and their customers alike.

Regionalization helps two or more water systems to leverage and combine resources, equipment, personnel, and even physical plants. According to U.S. EPA, “the main benefit of regionalization is that it pools individual resources of two or more water systems to obtain services or facilities that one or both systems may not have been capable of obtaining by themselves.”

In the Rural Community Assistance Partnership's (RCAP's) 2021 report: Affordability and Capability Issues of Small Water and Wastewaters Systems: A Case for Regionalization of Small Systems, they feature a case study that shows a successful model for regionalization from the Greater Cincinnati Water Works (GCWW) in southwest Ohio. GCWW offers the smaller water systems in the area much assistance in the form of: lab testing services, billing services, call center operation, a source of project financing, construction management services, engineering services, and emergency help when needed. 

RCAP also released a report titled: Regionalization: RCAP’s Recommendations for Water and Wastewater Policy which contained 22 recommendations that should be integrated into policy decision-making. The research featured in this report was unveiled in a webinar that also focused on the experiences of five different states: California, Florida, Ohio, Pennsylvania, and Texas, who spoke about what they have put in place to help support the various forms of regionalization.

Further Regionalization Readings & Resources:

• Benefits of Regionalization
• How Regionalization & Consolidation of Water Utilities Creates New Projects
• Rural Matters | Issue 4: Let’s Talk Regionalization (2022)
• Learn About Water System Partnerships
• State Action on Water System Regionalization and Consolidation
• Developing Regional Economic Connectivity: Key Factors and Strategies for Urban and Rural Communities
• Funding Strategies to Promote System Regionalization

RCAP’s Free Quarterly Magazine is Focused on Rural Communities

Rural Matters is the official magazine of the Rural Community Assistance Partnership (RCAP.) It features stories and insights that highlight the challenges and opportunities facing the rural communities that RCAP works with. Rural Matters is published quarterly in both print and digital formats and RCAP offers an archive of past issues on their website. Below are links to some of the most recent issues:

2022 | Issue 1: Let’s Talk Wastewater features topics like: loan management, the water access gap, mapping a septic system on tribal lands, developing an effective sewer board, and managing wastewater in U.S. territories.

2022 | Issue 2: Let’s Talk Drinking Water features topics like: boil water advisories and orders, COVID-19’s impact on water systems, violations and how the Agreed Order process works, options for additional water supply, and Lead and Copper Rule Revisions.

2022 | Issue 3: Let’s Talk Solid Waste features topics like: purchasing a solid waste collection vehicle, how a pandemic impacts solid waste management, a story of solid waste success in South Dakota, recycling program adaptation, and the unique challenges that come with solid waste management in the Grand Canyon.

2022 | Issue 4: Let’s Talk Regionalization features topics like: winterization tips, well ownership, a regionalization success story, fleet electrification, and multiple articles that emphasize the importance of community collaboration with water and wastewater systems.

If you’re interested in contributing feedback or advertising in Rural Matters you can contact submissions@rcap.org or you can simply subscribe to receive each issue.