Private Well Water Treatment
If bacteria, parasites, and chemicals are in your well water, you can improve the quality of the water with treatment. To make sure your water is safe for drinking, testing is your first step. When test results show that your drinking water contains contaminants at levels above the safe limit, an appropriate water-treatment system or use of a clean alternative source of drinking water (e.g., bottled water) is recommended. Long term, a more cost-effective solution for homes on private well water may be filtration systems such as a point of use reverse osmosis (RO) system or an ion exchange system.
Talk to water treatment companies and learn the pros and cons of treatment systems. Choose one that best meets your water quality needs by removing or reducing the bacteria and chemicals found in your water. If you decide to purchase a water treatment system, it is recommended that you purchase a unit that is NSF International (or American National Standards Institute (NSF/ANSI) certified. These products are certified, and verified, to reduce a certain contaminant or contaminants (constituents) from the water.
Water Treatment Basics
There are different reasons for choosing a treatment system and a single system may not meet all the treatment needs of a well owner. Reasons for selecting a water treatment system may include:
- Remove something specific from the water such as: metals or bacteria.
- Protect sensitive household members such as: children, seniors, or those with compromised immunity (like a chronic illness).
- Improve taste.
Water treatment systems can be for use at a tap or for the whole house, or in combination.
- Point of Use at a single tap such as a kitchen faucet (includes pitcher filters).
- Point of Entry treats the water entering a home.
After you test your water, it is important to understand what the results mean. See the Water Test Interpretation Tool in Downloads and Resources below to understand your test results and some treatment options. Other resources include the Water Quality Interpretation Tool from Colorado State University and information from The National Groundwater Association.
These resources can help you select an appropriate water treatment system, if needed. If test results show that your drinking water contains contaminants at levels above the safe limit, you can improve the quality with treatment. An appropriate water-treatment system or use of an alternative source of drinking water, such as bottled water is recommended.
Types and Methods of Water Treatment
Filtration
- A water filter removes impurities from water when contaminants stick to the surface or in the pores of a filter medium.
- Filtration may need to be combined with other pre-treatments (such as adjusting pH).
- Examples of filtration systems include activated carbon filters (including pitcher filters) and reverse osmosis (RO) systems.
- Filtration can include different pore sizes, capturing different types of contaminants.
- Filters can protect against protozoa, bacteria, viruses, and some chemicals.
Water Softeners (Ion Exchange)
Water softeners use ion exchange technology to remove chemicals that have a positive or negative charge (ions). Most frequently used to reduce the amount of hardness (calcium, magnesium) in the water. Some models are also designed to remove other chemicals such as: iron, manganese, heavy metals, some radioactivity, nitrates, arsenic, chromium, selenium, sulfate, and uranium. They do not protect against protozoa, bacteria, and viruses.
Distillation
Distillation systems heat water to the boiling point and then collect the water vapor as it condenses, leaving many of the contaminants behind. Distillation can remove chemicals such as arsenic, barium, cadmium, chromium, lead, nitrate, sodium, sulfate, and many organic chemicals. It also removes microorganisms like protozoa, bacteria and viruses.
Ultraviolet (UV) Light
Ultraviolet light is used to disinfect (reduce amount the number of bacteria or other microorganisms) in water. It is often combined with pre-filtration, reduces microorganisms like protozoa, bacteria, and viruses. It is not effective at removing chemicals.
Removing Metals (Like Arsenic and Uranium) from Your Drinking Water
Different methods can be used to reduce metals, such as arsenic and uranium, in drinking water. Boiling your water will increase, not decrease, metals concentration. Some treatment options include:
- Reverse osmosis (RO) a type of filtration that works by having water pass from a more concentrated solution to a more dilute solution through a semi-permeable membrane. RO systems often include additional filtration.RO systems are fairly small and are usually placed under the kitchen sink (point-of-use). Properly installed and maintained RO systems will remove many contaminants from drinking water such as, arsenic, fluoride, uranium, radium, nitrate, chromium, lead, copper, sulfate, phosphorous, sodium, chloride, calcium, magnesium, and potassium.
- Ion exchange/water softeners: Some models are designed to remove iron, manganese, heavy metals, some radioactivity, nitrates, arsenic, chromium, selenium, sulfate and/or uranium.
- Distillation can remove chemicals such as arsenic, barium, cadmium, chromium, lead, nitrate, sodium, sulfate, and many organic chemicals.
- Options for reducing arsenic. If test results show a concentration of arsenic greater than the Environmental Protection Agency's (EPA) national drinking water standard for arsenic is 10 micrograms per liter (mcg/L), treatment or alternate clean source of drinking water is recommended. Use treated water for all water you drink and cook with, including beverages and food. The type of treatment will depend on the type of arsenic in the water and other water chemistry. Some options, including reverse osmosis, adsorptive media filter, and distillation are shown in the table below. If you decide to purchase a reverse osmosis, or other treatment system it is recommended that you purchase a unit that is certified to reduce arsenic.
- Options for reducing uranium. If test results show that your drinking water contains more than 30 micrograms per liter (mcg/L) of uranium, an appropriate water-treatment system or use of clean alternative source (e.g., bottled water) of drinking water is recommended. Point-of-use (at the kitchen sink) reverse-osmosis (RO) treatment units can reduce uranium concentration in drinking water. Properly operated household RO units can remove up to about 90 percent of the uranium from the raw water. It is recommended that you purchase a unit that is NSF International Certified and is effective in filtering radium (Ra-226 and Ra-228). Other treatment methods, such as distillation and an ion exchange can also reduce uranium concentrations.
Removing chemicals (like nitrate) from your drinking water
The EPA national drinking water standard for nitrate is 10 milligrams per liter (mg/L). If test results show a concentration of nitrate greater than this amount, treatment or an alternate clean source of drinking water is recommended. Use treated water for all water you drink and cook with, including beverages and food.
Nitrate toxicity can cause illness, with the most vulnerable population being infants. Infants below four months who drink water containing nitrate above 10 mg/L could become seriously ill with blue baby syndrome (methemoglobinemia). Symptoms of this nitrate toxicity include shortness of breath and bluish skin coloring. Some options for reducing nitrate in water include reverse osmosis, ion exchange, and distillation.
Removing perfluorinated compounds (PFAS) from your drinking water
Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals, including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), and are known as the "forever chemical". PFAS persist in the environment and move through soil and can contaminate groundwater and have potential for accumulation in the food chain and human body. These chemicals have been widely used for decades in consumer and industrial products to make them non-stick and water resistant. They are found in firefighting foams, protective or stain resistant coatings for fabrics and carpets, paper coatings, insecticide formulations, paints, and cosmetics. PFAS can persist in the environment and move through soil and contaminate groundwater. A list of water treatment options for removal of perfluorooctanoic acid (PFOA) and perflurooctane sulfonate (PFOS) can be found in the table below.
| Treatment Type | Notes | Application | PFOA Removal Rates | PFOS Removal Rates |
|---|---|---|---|---|
| Membrane Filtration (Reverse Osmosis (RO) and Nanofiltration) | Multi-contaminant removal. Waste/by-products must be managed. Mineral addition may be necessary. | Households (RO), Groundwater, Surface Water, Public Water Systems | >90% | >90% |
| Granular Activated Carbon(GAC) | GAC is the most common treatment method for PFAS removal. Presence of other organic compounds may reduce effectiveness. | Households, Groundwater, Surface Water, Public Water Systems | >90% | >90% |
| Powdered Activated Carbon(PAC) | High concentrations of PAC are necessary. Required high concentrations may make this an infeasible option for water treatment. Waste residuals may create a challenge for disposal of waste products. | Households, Groundwater, Surface Water, Public Water Systems | >90% | >90% |
| Anion Exchange | Single-use systems require replacement and proper disposal. Regenerable systems produce brine that must be disposed of responsibly; such systems are automated, have small footprints and high regeneration efficiencies. Competition with naturally occurring minerals can impact effectiveness. | Groundwater, Surface Water | 10-90% | >90% |
| Advanced Oxidation (UV/H2O2; UV/S2O8) | Low removal rate. Can destroy pollutants to produce less complex compounds. Other organic contaminants will reduce efficiency. | Groundwater, Surface Water | <10% | <10-50% |
Adapted from: National Ground Water Association (NGWA) document: Groundwater and PFAS: State of Knowledge and Practice (member available document). Table Source: Cheremisinoff , N. P. 2016. Overview of Water Treatment Technology Options in: Perfluorinated Chemicals (PFCs): Contaminants of Concern. Scrivener Publishing. Beverly, MA. ISBN 978-1-19-36353-8.
There are some considerations when choosing a treatment system for PFCs/PFAS:
- Boiling your water will not remove perfluorinated compounds from drinking water.
- Reverse osmosis systems (if installed and maintained properly) can be more than 90 percent effective at removing a range of PFAS compounds (see table below for a list of water treatment options for removal of PFOA and PFOS). This treatment system does generate some waste water, therefore, a point-of-use system (under the sink) is recommended as the amount of waste water produced will be less than with a whole house system. Further, this type of water treatment system can generate a waste containing high concentrations of removed chemicals present in the water supply. Therefore, proper or safe disposal of such waste should be considered and planned for.
- The treatment option should be certified (to meet the American National Standards Institute (ANSI) standards) to reduce the contaminant of concern below the EPA health advisory level. Find certified treatment options through NSF International (1-800-673-8010) or the Water Quality Association (1-630-505-0160).
- If you decide to purchase a filtration system, hire a company that has experience in successfully removing toxic chemicals in private domestic well water. The treatment system should be installed by a plumber licensed by the Construction Industries Division of the N.M. Department of Regulation and Licensing, and you should purchase a maintenance service contract for the system.