Several types of regulations are currently used to protect domestic wells. The most common are water well construction regulations, which are used by many jurisdictions to ensure that water wells are properly constructed and resilient to contamination from shallow groundwater and contaminants at the ground surface. The goals of most well construction regulations are to: protect the health and safety of the well owner and the environment, protect aquifers and water resources, protect aquitards (i.e., low permeability geologic formations that restrict the flow of groundwater and contaminants between aquifers), and protect groundwater quality and quantity. Well construction regulations typically specify who can construct a well (e.g., a licensed well contractor), the methods and materials that must be used, setback distances from potential sources of contamination, requirements for well development, requirements for sealing abandoned wells (so they do not provide pathways for contaminants to reach aquifers), yield testing, and reporting (water well records). In some jurisdictions, the well construction regulations require that a permit be obtained before a domestic well is constructed (e.g., Colorado and Wyoming, USA). The key elements of water well construction regulations that help protect wells from surface contaminants and shallow groundwater contamination include requirements for a sanitary well cap, adequate well casing, and an annular seal.
Water well construction regulations are usually applicable to the construction of all types of water wells, including domestic wells. In most cases, they apply at the time of well construction and are the only regulations a domestic well owner is required to follow. They do not usually include any chemical testing or ongoing maintenance and monitoring requirements. Specific examples of water well construction regulations include the Province of Ontario’s Regulation 903 (Province of Ontario, 1990) and Kansas State’s Article 30 (State of Kansas, 2013).
Other types of regulations used to protect domestic wells are those that require water quality testing at the time of well construction or during a property sale. Although these types of regulations have not been widely adopted, a limited number of jurisdictions require initial testing when a domestic well is first installed (e.g., New Brunswick, Canada, and North Carolina, USA) and during real estate transactions (e.g., New Jersey, Oregon, and Rhode Island, USA). Examples of water quality testing regulations for domestic wells include the Canadian Province of New Brunswick’s Potable Water Regulation (Province of New Brunswick, 1993) and the State of New Jersey’s Private Well Testing Act (Atherholt et al., 2009). These one-time sampling requirements can be an effective way to identify existing contamination at a point-in-time, but they do not identify seasonal or future changes to water quality like regular testing can. A study that looked at the frequency of testing for arsenic in domestic wells in both the United States and India concluded that because of temporal variations in arsenic levels in wells, a single test is inadequate to ensure that well water meets water quality guidelines in the long-term (Mailloux et al., 2021). The study found that in order to have less than a 5 percent chance of exceeding the guideline in the future, wells must be tested every year if the concentration in the well water is more than half the guideline, and every five years if the concentration is less than half the guideline. A study in Ontario, Canada reviewed 700,000 E. coli sample results from more than 200,000 domestic wells and concluded that, because of temporal variations in E. coli detections, one sample is not enough to determine the long-term microbiological safety of domestic wells (Latchmore et al., 2020).
Some jurisdictions have regulations for protecting domestic wells in subdivision developments (Figure 20) which require a hydrogeological assessment prior to the subdivision’s approval. These assessments look at both groundwater quality and quantity issues and evaluate whether future problems are likely and what mitigation measures can be used to lower the risks. For example, if an assessment indicates that the proposed density of lots (the land designated for one home) in a subdivision will result in excessive well interference or aquifer depletion, the number of approved lots can be reduced.
The introduction of regulations to protect domestic wells in subdivisions has often been in response to historical problems. For example, the Province of Ontario, Canada, introduced requirements for hydrogeological studies in subdivisions (Ontario Ministry of Environment and Energy, 1996) after a number of subdivisions with domestic wells were found to have groundwater quality problems, including high nitrate levels from on-site septic systems. In Nova Scotia, Canada, hydrogeological study requirements for subdivision developments were introduced after well interference problems in a subdivision caused numerous domestic wells to go dry and necessitated the extension of central municipal water services. The Nova Scotia guide for hydrological assessments in subdivisions now includes a spreadsheet tool for evaluating the water balance for the planned number of lots and the interference between wells on each lot (Nova Scotia Environment, 2011).
Many jurisdictions regulate groundwater pumping with a permit system and require approvals for certain industrial activities (e.g., quarries, mines, landfills, petrochemical facilities). Examples of using permits to regulate pumping are provided by Nowlan (2005). Requiring permits for pumping and approval of activities are not specifically designed to protect domestic wells, but they sometimes require the proponent to identify nearby domestic wells and evaluate the potential impact that the proposed activity may have on water wells. Permits for these activities may include conditions that protect existing domestic wells, such as baseline surveys (e.g., water quality testing, water level measurements), contingency plans to address well interference problems, and requirements to remedy any impacts on domestic wells caused by the proposed activity. Examples of groundwater permitting systems that address effects on existing water wells include the State of Arizona’s well spacing and impact rules (Arizona Department of Water Resources, 2021) and the Canadian Province of Nova Scotia’s groundwater withdrawal approval process (Nova Scotia Environment, 2010).