Sanitary Surveys: Assessing Risks to Drinking Water Supplies
By Kelly A. Reynolds, MSPH, PhD
Waterborne outbreaks and disease result primarily from microbial contamination. Water providers are required to routinely monitor source and treated water supplies to ensure safety. In addition, proactive approaches toward protecting public health from harmful contaminants include the use of sanitary surveys. Under the Safe Drinking Water Act (SDWA), states, territories and tribes are required to perform routine inspections of water sources, distribution channels and other critical control points of management, maintenance and delivery. (Recently, researchers have studied the ability of sanitary survey scores to predict water quality at the point of use.)
Sanitary surveys (SS) are on-site, physical inspections by representatives from the state primacy agency, as delegated by US EPA. State primacy refers to the responsibility of primary enforcement authority at the local (i.e., state, territory or tribal) level, which includes the oversight of eight target inspection areas relative to a drinking water system (Table 1). In addition to conducting sanitary surveys of public water systems, primacy agencies carry out a list of key activities as designated by public water system supervision (PWSS) programs. These activities include:1
- Developing and maintaining state drinking water regulations
- Developing and maintaining an inventory of public water systems throughout the state
- Developing and maintaining a database to hold compliance information on public water systems
- Conducting sanitary surveys of public water systems
- Reviewing public water system plans and specifications
- Providing technical assistance to managers and operators of public water systems
- Carrying out a program to ensure that the public water systems regularly inform their consumers about the quality of the water that they are providing
- Certifying laboratories that can perform the analysis of drinking water that will be used to determine compliance with the regulations
- Carrying out an enforcement program to ensure that the public water systems comply with all of the state’s requirements
All US states and territories (except Wyoming) have primacy relative to public water system programs of the SDWA. In Wyoming, US EPA Region 8 Office in Denver, CO implements these programs. Although US EPA provides detailed guidelines for SS inspections,2 individual primacy agencies may have unique standardized protocols and checklists. Inspections are not limited to state agencies; a network of private vendors and local health officials may also be consulted in certain states.
Why conduct a sanitary survey?
The purpose of an SS is to identify potential problems that may affect the safety of tap water supplies, including health hazards and sources of environmental contamination. Inspections often begin with a review of system schematics and maps, as well as operator treatment and monitoring records, followed by field analysis. Site assessments can confirm that providers are compliant with state and federal standards and guidelines and are up to date with their system information.
Also, third-party inspections provide opportunities for educating providers on proper procedures for maintaining a safe water supply and to establish a relationship for outreach and assistance. Theoretically, with proper training, water utility managers can use these site inspections to predict water quality vulnerabilities and develop targeted management plans.
Variability among different inspectors is also a possibility, although no US studies were found where the reproducibility of SS scores among different inspectors was studied or that indicated this was a concern. Given that community drinking water systems may be highly varied and complex, many state primacy agencies and local municipalities have developed customized checklists for detailed assessments.
Can sanitary surveys replace water quality monitoring?
Some water providers have suggested that SS could substitute for direct water quality monitoring, particularly in resource-limited, developing countries. The implementation of analytical water monitoring tools involving the culture of microbes or isolation and analysis of chemicals from collected samples, can be challenging given specialized handling protocols and laboratory resource needs.
Several studies have compared SS information to drinking water quality data to determine if SS data is reliably predictive of health-related contaminant risks. One study in Bangladesh compared E. coli monitoring results to sanitary inspection scores of groundwater sources.3 (E. coli is commonly used in the US and globally as a waterborne indicator of fecal contamination.) In this study, 1,684 water samples were collected from 902 wells with SS data. Sanitary risk scores were compared to E. coli data to determine if they were a good predictor of water quality. E. coli was detected in 41 percent of the wells. Sanitary scores were used to characterize the water supplies as low risk (31 percent), medium risk (45 percent) and high or very high risk (25 percent). The probability that the sanitary survey correctly predicted hazardous water quality, as evidenced by E. coli presence, was less than 50 percent. Thus, sanitary scores in this scenario were not associated with the presence or concentration of E. coli. Similar studies have been conducted in other global regions but not in developed countries.
Sanitary surveys are seen as supplemental to, not a replacement for, analytical monitoring tools. Community water systems (CWS) that supply water to at least 25 people year-round and have at least 15 service connections are required to conduct an SS every three years, compared to non-community water systems. Suppliers who supply water to at least 25 people at least six months out of the year (i.e., schools, office buildings, hospitals) or who are transient users (i.e., gas stations, campgrounds) are inspected every five years. In addition, CWS with outstanding performance based on prior survey results are permitted to extend their testing frequency to every five years.
Significant deficiencies identified in the SS must be addressed according to a determined schedule to avoid a citation by US EPA. The default corrective action date is six months from the time the inspector’s report is received and notification sent to the agency within 30 days of the mitigation action. If providers cannot address the deficiencies in the allotted time, extensions can only be granted by US EPA.
While SS are another tool to protect municipal water supplies, they also highlight present concerns. Real-world examples of significant deficiencies include dead animals in storage tanks, improperly sealed wellheads, close contact with human or animal wastewater sources, cross-connection gaps, leaking finished water tanks, storage tanks not cleaned properly, lack of a monitoring plan, lack of an emergency management plan, etc. Deficiencies could be present for years before they are identified, further supporting the additional proactive approach of having a final treatment barrier at the point of use.
- US EPA O. Public Water System Supervision (PWSS) Grant Program. https://www.epa.gov/dwreginfo/public-water-system-supervision-pwss-grant-program. Accessed November 6, 2020.
- US EPA Office of Water U, of Ground Water O, Water D. How to Conduct a Sanitary Survey of Drinking Water Systems A Learner’s Guide: Designed to Assist in the Delivery of a Sanitary Survey Training Course.
- Ercumen A; Naser, A.M.; Arnold, B.F.; Unicomb, L.; Colford, J.M.; Luby, S.P. Can sanitary inspection surveys predict risk of microbiological contamination of groundwater sources? Evidence from shallow tubewells in rural Bangladesh. Am J Trop Med Hyg. 2017;96(3):561-568. doi:10.4269/ajtmh.16-0489
- US EPA. Sanitary Surveys | Drinking Water Requirements for States and Public Water Systems. https://www.epa.gov/dwreginfo/sanitary-surveys. Accessed November 6, 2020.
About the author
Dr. Kelly A. Reynolds is a University of Arizona Professor at the College of Public Health; Chair of Community, Environment and Policy; Program Director of Environmental Health Sciences and Director of Environment, Exposure Science and Risk Assessment Center (ESRAC). She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a doctorate in microbiology from the University of Arizona. Reynolds is WC&P’s Public Health Editor and a former member of the Technical Review Committee. She can be reached via email at email@example.com