Author: Joseph Cotruvo, PhD BCES, President, Joseph Cotruvo & Associates LLC
Small drinking water systems have always been a vexing problem. Fortunately, most small systems utilize groundwater which is generally more stable and higher quality than surface waters, requiring less treatment or none. But there are many exceptions. Some exceptions include need for treatment for some natural and human source contaminants, microbial contamination, and excessive corrosion.
When there is a contamination or an infrastructure problem, small systems are at a great financial and personnel disadvantage. Small water systems lack economies of scale which limits their access to persons with appropriate expertise when issues arise. Even if the water quality is good and/or technology is installed, the operation and maintenance and distribution infrastructure issues are still substantial. There are practical lower cost solutions to ensuring safe drinking water in small communities, but it requires prioritizing resources.
What are small systems?
There are about 150,000 public water systems that meet the Safe Drinking Water Act “public water system” definition of serving 25 persons or having 15 service connections. About 50,000 of these public water systems are community water systems that serve resident populations. The remainder are non-community systems that serve non-residents averaging at least 25 persons per day, like rural schools and factories or summer camps.
These 50,000 community water systems provide regulated tap water to over 300 million people. There are about 4,100 large systems with populations greater than 10,000 and they serve about 260 million people. About 5,100 medium systems have populations between 3,301 and 10,000 and they serve about 29 million people. There are about 43,000 small systems with populations ranging from 3,300 down to 25 and their total population is only about 8 million.
The logistic and economic challenge of providing safe drinking water in 43,000 locations with small populations and limited resources is painfully obvious. Most small systems operate with informal local management. Unfortunately, they may not have the technical expertise, time, or resources to be familiar with all the regulatory requirements, provide the required monitoring and reporting, and make appropriate decisions when problems arise.
In the original Safe Drinking Water Act legislative history, Congress encouraged small systems to consolidate and share resources. That is called a “punt” in the vernacular. Most small systems are not located near others, so physical consolidation is often not an option. Political or administrative consolidation is also difficult.
Small systems frequently receive minimal and infrequent oversight from state regulators because of their staffing limits, priorities, and the large numbers of systems to be dealt with. The best feasible treatment technology to be expected in most cases is chlorination. Other technologies usually require more engineering and decision elements, greater cost, and operating support. Some federal funds are available via the State Revolving Fund, but the application processes are not easily applied by non-professional locals.
Some of the most common small system and also home well contamination problems include: nitrate and nitrite in groundwater from agricultural fertilizers and septic tanks, herbicides like atrazine that are widely used, and arsenic from natural deposits. These contaminants are mobile in water, and they can migrate beyond sources.
So, what can be done to try to overcome the barriers to providing consistent good quality water in stressed small drinking water systems?
Some possible methods for providing safe drinking water in small systems
In general, circuit riders as well as some non-central treatment approaches might be solutions in many instances, especially when the water is microbially safe. The latter can include:
- Community provided bottled water
- Community provided point-of-use (POU) treatment
A community circuit rider system helps by having a qualified professional who supports several small community water systems. Their services can include operational management and oversight along with other services. Full time presence is generally not needed, but regular on-site and on-call service providers provide the economies of shared costs and access to a qualified person to handle technical and monitoring needs, as well as perhaps regulatory reporting requirements.
Community provided bottled water
Community provided bottled water is allowed in emergency situations usually when a microbial contamination is occurring, but it is not usually acceptable as a long-term solution. It can, however, be a reasonable solution when the costs and feasibility of central treatment are not amenable. Less than 1% of tap water is consumed for drinking and food preparation. The other 99% is used for flushing toilets, washing, and watering lawns. There may well be sufficient economies of scale even in a small community for providing bottled water, including as from 5-gallon water dispensers in the home that would be provided and replaced by a contractor.
This is especially feasible for non-microbial MCL exceeders, to eliminate the potential for inadvertent exposures. Nitrate and nitrite are a risk for infants up to about 6 months of age especially when the water has microbial contamination, and it is difficult and costly to treat. The water should be disinfected, and bottled water is often provided as an emergency protection for infants.
Community provided point-of-use (POU) treatment
Community provided point-of-use (POU) treatment is being applied in some small locations. The U.S. EPA and some states allow community POU for compliance for most non-microbial MCL exceeders, however, with some inappropriate stipulations, which could be remedied. Herbicides and other organic chemicals can be treated by selected granular carbon POU devices supplied and installed in the home and managed centrally.
Arsenic is a good example where community wide -POU can be applied successfully at reasonable cost with a different treatment system using activated alumina or iron oxides/iron hydroxides or titanium dioxide in under sink cartridges installed at the kitchen tap. There are perhaps several thousand small communities with source waters that exceed the arsenic MCL.
NSF International and I carried out an EPA funded comprehensive demonstration project for a year in a rural California community of about 400 persons. We worked with a nearby Kinetico expert POU provider who installed the units in about 170 locations, including homes and businesses including restaurants. The iron modified aluminum oxide units were installed efficiently with supplied maintenance and the cartridges were replaced as needed, and compliance monitoring was performed. It was successful and much appreciated by the residents. Costs were projected to be about half the cost of central arsenic removal treatment.
We concluded that the best circumstance would be for a community to contract with a qualified service provider to carry out all of the installation and maintenance, monitoring and reporting requirements. The service provider would be acting as an agent of the community with oversight from the state, relieving the state of some of its workload. Such a concentrated and guaranteed client base should provide mutually beneficial economics for both the provider and the community.
Small water systems continue to struggle when there is a contamination or an infrastructure problem, and they are at a great financial and personnel disadvantage. But there are non-traditional practical resources and solutions available for many small communities that could assure consistent safe drinking water in small communities. Ensuring consistent safe drinking water in small communities requires prioritizing resources, local circumstances, comparative costs, practical considerations and state assistance and acceptance can determine the choices.
This is being studied intensively in some states, for example, the California Drinking Water Needs Assessment. Council member Chad Seidel and his colleagues worked alongside other water professionals to evaluate the current challenges facing safe and affordable water supply in California. Read more here.