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Private Wells

The Importance of Well Water Quality

One of the ten greatest public health achievements of the 20th century was the treatment of drinking water, including disinfection. This resulted in a dramatic decrease in diseases such as typhoid and cholera. Although most New Mexicans have access to drinking water that meets standards under the national Safe Drinking Water Act, private well owners and users should periodically test their well water to ensure that is meets the same safe drinking water standards.

About 13 percent of the population in New Mexico (or an estimated 270,000 people) receive their water from a private well. Owners of private domestic water wells are the best protection of their water supply; the water quality of a private well is unregulated in the state of New Mexico.

New Mexico Private Well Owners Handbook 2024

How groundwater recharges.

Groundwater Basics

  • Private wells use groundwater which simply put, is water that is naturally underground.
  • A groundwater aquifer is water that is stored in and moves slowly through permeable rocks.
  • Precipitation sources such as monsoon rains and snowpack provide a way to "recharge" the aquifers or replenish the water that is pumped out of wells across the state.
  • A small portion of precipitation soaks into the earth and overtime migrates down through the soils (unsaturated zone) until it reaches the water table and enters the aquifer.

Influences on well water quality

Drinking water quality can be influenced by natural sources, such as minerals in bedrock; man-made sources, like chemicals, agricultural run-off, or plumbing fixtures; or natural disasters, such as flooding or drought. We call naturally occurring drinking water components constituents. Common constituents in groundwater in New Mexico may include arsenic, uranium, fluoride, manganese, selenium, nitrates, sulfate, and bacteria. When there is an absence of groundwater recharge, such as due to drought or large water draws, the concentration of these constituents could increase. Therefore, it is important for people who rely on private wells to test the quality of their drinking water. Microorganisms such as bacteria, parasites, or viruses can be naturally present in the environment or can be introduced into water by contamination from human or animal waste (fecal waste). These can also influence the water quality from private wells. Some, such as iron bacteria only cause changes in odor or taste while others, such as some strains of E. coli bacteria, can cause illness, sometimes severe.

Well ownership

Well owners are the best source of protection of for their water supply. The water quality of a private well is unregulated in the state of New Mexico (there are some city and county policies that apply to wells such well permitting, but not the quality of the water from wells). Well owners are responsible for well maintenance, protecting their water source, testing, and when applicable treating their water. They are also responsible for knowing the history and maintaining records of their well.

Well owner tips

Private well owners in New Mexico should test their drinking water:

  • Every year for bacteria, nitrate, pH, and conductivity.
  • At least once for fluoride, arsenic, uranium, and anything (constituent) that is of concern due to proximity of a nearby potential source.
  • For manganese if your well water is found to have levels of uranium or arsenic above the respective Environmental Protection Agency (EPA) maximum contaminant level (MCL). This is because manganese can interfere with the removal of uranium and arsenic from the water.
  • Retest when changes in terrain occur due to disasters (fires, floods, and runoff).
  • When tests are offered in their area through state-sponsored water test fairs.

The benefits of testing include knowing what is in the water you drink; you will be advised of the presence of constituents that have potential to harm your health. Test results will guide you in finding proper treatment for minimizing the potential for health risk.

Common questions about well water quality

My water comes from a private well. How do I know which water treatment I should get?

1. Get the water tested by a third-party environmental laboratory, preferably a certified lab. It is important to have the water tested by an entity that is not selling you equipment. You can also take advantage of occasional water fairs offered by the State Environment Department and in part, by the State Health Department.

2. Educate yourself on the types of water treatment which will remove or treat the constituent you are concerned about.

3. After installation of treatment, test the water again.

Does the condition of my well have anything to do with the water quality?

Water quality is dependent on a number of considerations which include well construction, location, and regular maintenance. It is also depending on the local environment, which includes the quality of the aquifer from which water is drawn (which can change over time) and human activities in the area that can affect the well water.