Nitrates (NO3) are chemical compounds — naturally formed when soil microorganisms fix or break down atmospheric nitrogen or ammonia — that, in high concentrations, represent a concern for both ecological and public health. Nitrates are highly soluble in water and rapidly enter surface and groundwater systems when exposed. This creates a public health concern where high levels of nitrate present in surface or groundwater sources can lead to high levels of nitrate contamination in drinking water.
Because nitrates are odorless, colorless, and tasteless, their presence in drinking water is not detectable without conducting a chemical test. As such, absent requirements for testing and dissemination of testing results to the public, nitrate contamination of drinking water represents a latent public health concern, especially in areas where high levels of nitrate contamination are present.
Human activity has greatly increased the amount of nitrate present in ground and surface water systems, including sources stemming from sewage and septic units, landfills, and most notably, application of fertilizers. The U.S. Environmental Protection Agency (EPA) has established nitrate to be a risk to human health, particularly as relates to methemoglobinemia, commonly referred to as blue baby syndrome, and has set a maximum contaminant level (MCL) of 10 mg/L as a safety threshold in public water systems. This threshold, however, is based on studies that are more than 70 years old, and recent examinations of the impact of nitrate on human health is demonstrating a link to negative health outcomes below the 10 mg/L threshold set by EPA, as well as links between nitrate exposure and the development of a variety of cancers and other diseases.
The 10 mg/L threshold is, under the federal Safe Drinking Water Act, an enforceable standard for public drinking water systems, with the majority of states (including Virginia) holding primary responsibility to ensure public systems test their water for contaminants, including nitrate; provide public notice of the levels of contaminants in the system; and engage in remediation efforts should contaminant levels exceed the safety threshold. Although violations do occur, this creates a reasonably robust system for testing, data collection, public notice, and protection.
However, although EPA and many state agencies (including the Virginia Department of Health (VDH) that oversees enforcement of public water systems in the Commonwealth) recommend private well systems initiate their own testing and apply the 10 mg/L threshold, there is no requirement for either testing or maintaining safety in these private systems. This represents a health risk for the roughly 1.7 million Virginians who rely on private well systems to source their drinking water.
Critically, in Virginia, there is little comprehensive information on the distribution and severity of nitrate contamination in private well systems, due to a lack of uniform testing and data collection protocols within state agencies, as well as the impact of contamination across communities facing worse socioeconomic conditions and lower access to healthcare.
Our recommendations
To better protect the health and safety of Virginians, the Commonwealth should take the following actions:
- Expand the Virginia Cooperative Extension Program’s well testing program, as well as provide a compensation program to offset costs for well water testing, sampling, and analysis directly through VDH.
- Require testing for nitrate (and other priority contaminants) at the time of drilling alongside the initial coliform test.
- Require all testing data to be collected and stored by VDH’s office of drinking water (or a similar agency office) while providing a method for individuals who voluntarily test their water to submit results to VDH for data collection.
- Expand education and outreach programs, including funding, related to nitrate and other contaminants in private well systems, with VDH and local health districts playing a pivotal role in developing awareness of potential concerns and the need for testing.
- Direct VDH to create a public-facing database that provides disaggregated data on nitrate contamination in private wells in the Commonwealth, using voluntarily submitted as well as agency-collected data.
- In the instance of high concentrations of nitrate contamination in a given geographic region (census tract or county), VDH should instruct the local health district responsible for the region to publicly disseminate information to private well owners to notify them of risk.
- Require nitrate testing disclosure by seller to buyer as part of a real estate sale transaction (placing well conditions on par with septic conditions).
- Require nitrate testing to be conducted by owners of properties that source their water from a private well who lease their property to tenants. Testing should be conducted prior to the start of leasing the property and every three years while the property is being leased. When nitrate levels test in excess of 10 mg/L, the owner should immediately provide notice to the tenant and take corrective steps to remediate within 60 days, or be subject to fines from VDH.
- Increase funding streams, particularly grant funding to private well owners, to facilitate remediation and ensure safe drinking water when contamination is present, with special focus on low- and moderate-income households.
- VA DEQ should maximize and streamline its permitting and reporting data to allow for greater transparency and public access, as well as coordinate with VDH to highlight instances of violations and possible spikes in contamination sources to provide notice and warning in regions with private wells near the violation source.
- Maximize Virginia Agricultural Cost Share and other BMP funding for small farms and prioritize groundwater BMPs to address nitrate runoff from manufactured and manure fertilizers and animal waste into groundwater aquifers.
The U.S. Environmental Protection Agency should take the following actions:
- Re-evaluate nitrate’s MCL based on current epidemiological studies related not only to methemoglobinemia, but to emergent studies on nitrate’s association with cancer, as well as thyroid and other diseases.
- Increase funding opportunities for private water systems to assist populations, who are often socioeconomically disadvantaged, to remediate their source of drinking water. This can include specific funding within Drinking Water State Revolving Fund (DWSRF) for building out community water systems in areas of high private system contamination, or similar funding streams targeted to private water systems.
