Residents relying on a private groundwater well for their household water are responsible for ensuring the water is safe for drinking. HGIC 1902, Residential Drinking Water Well: Water Quality provides information about priority water quality parameters and recommended testing schedules. If sampling results indicate problems with water quality, additional actions should be taken. Eliminating potential contamination sources and ensuring the well equipment has not been breached are important first steps that can promote safe drinking water in a cost-effective manner. If unable to resolve the cause of water quality concerns, then treatment options should be considered.
Water quality treatment can address health and safety concerns and/or can reduce taste, odor, or appearance problems. Common methods for water treatment include 1) removing impurities from water using physical, chemical, or biological methods; 2) modifying water quality parameters (e.g., reducing water hardness); and/or 3) disinfecting the water to kill microorganisms. Depending on treatment needs, equipment can be installed to treat all the water entering the home (a “whole-house” or “point of entry” system) or to treat a smaller amount of water for a specific use (a “point-of-use” system), see Figure 1. Point-of-use treatments are smaller systems, normally capable of producing up to 15 gallons of water per day, that are used to enhance water quality for drinking or cooking and are often located near the kitchen sink.1
Figure 1. Home water treatment systems can treat all the water flowing into the house or only the water used for specific purposes.
Image credit: Heather Nix, Clemson Extension.
Treatment Options
There is not one single option that treats all concerns, and, in some cases, a “treatment train” approach may be needed.1 The most appropriate treatment option(s) will depend on water quality concerns associated with a specific well. Table 1 provides an overview of general treatment effectiveness and is for educational purposes only; specific treatment decisions should be informed by a water well system professional.
Table 1. Summary of common treatment options for private drinking water wells. Information from CDC’s Drinking Water Treatment Technologies for Household Use,2 unless otherwise indicated.
| Treatment Systems | Household Water Contaminants | ||||
| Protozoa (e.g., Giardia, Cryptosporidium) |
Bacteria (e.g., E. coli, Campylobacter, Salmonella, Shigella) |
Viruses (e.g., Enteric, Hepatitis A, Norovirus, Rotavirus) |
Chemicals | ||
| Filtration (Physical) | Micro (pore size ~0.1 microns) |
++++ | ++ | – | – |
| Ultra (pore size ~0.01 microns) |
++++ | ++++ | ++ | + | |
| Nano (pore size ~ 0.001 microns) |
++++ | ++++ | ++++ | ++ | |
| Reverse Osmosis | ++++ | ++++ | ++++ | Will remove common chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead; may reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, fluoride, and phosphorus. | |
| Distillation | ++++ | ++++ | ++++ | Will reduce most common chemical contaminants, including arsenic, barium, cadmium, chromium, lead, nitrate, sodium, sulfate, and many organic chemicals. | |
| Ultraviolet (with pre-filtration) | ++++ | ++++ | +++ | – | |
| Water Softeners | – | – | – | Ion exchange technology for chemical or ion removal to reduce the amount of hardness (calcium, magnesium) in water; can also be designed to remove iron and manganese, heavy metals, some radioactivity, nitrates, arsenic, chromium, selenium, and sulfate. | |
| Disinfection | Chlorination destroys bacteria and microorganisms and removes dissolved iron, manganese, and hydrogen sulfide.1 See Disinfecting Your Well https://bit.ly/welldisinfection for specific instructions. | ||||
| Granular Activated Carbon Filters | Can be used for radon levels below 10,000 pCi/L3 | ||||
| Aeration Devices | Can be used for radon levels up to and above 10,000 pCi/L3 | ||||
| Table Key for Effectiveness: – (not), + (low), ++ (moderate), +++ (high), ++++ (very high) | |||||
The South Carolina Department of Health and Environmental Control (SCDHEC) provides private well water testing services and information regarding water quality parameters, including treatment options. Some of the more common treatment options are briefly discussed below.
Physical Filtration uses a physical, porous material to remove contaminants while allowing the water to pass through – basically functioning like a coffee filter. Different filtration system designs and filter materials provide removal of different contaminants and may vary in cost and maintenance requirements.
- Whole-house sediment filters are installed in the water line coming into the house and remove particulate matter. These enhance the effectiveness of and reduce the maintenance needs of other treatment systems that follow.
- Reverse osmosis (RO) systems remove dissolved minerals by forcing the water through a semipermeable membrane, which retains most of the ions while transmitting the water. When coupled with granular activated carbon filters before and after the RO treatment, this system can achieve a high degree of removal of many substances that cause water quality concerns.4
Disinfection includes various methods of killing microorganisms and can be applied to all incoming water or on an as-needed basis.
- Continuous disinfection is applied on a regular basis to kill microorganisms, including bacteria, and can be accomplished using various methods, such as adding a disinfectant or using ultraviolet light.1
- “Shock” chlorination – is typically recommended anytime a drinking water well is opened or serviced or when testing indicates the presence of bacteria.1 See Disinfecting Your Well Water: Shock Chlorination from UGA Extension for more information (https://extension.uga.edu/publications/detail.html?number=C858-4). Safety precautions should be taken, and hiring a professional to perform this task may improve successful implementation.
Ion exchange, such as deionization, includes a physical-chemical process that is most commonly used for water softening but can also be used for other treatments, including arsenic and nitrate.
Distillation units work by heating water to produce steam, which is collected and condensed back into water; because dissolved minerals will not vaporize, they are left behind in the heating chamber. These systems typically require frequent cleaning to remove the mineral salts and may result in a “flat” taste that can be reduced by aerating the water.4
In summary, there’s not a single “best” option for treating well water for residential use – specific solutions will depend on a variety of factors, including water quality, contamination concerns, and the needs of household residents. While much information is available online, a well water system professional can provide more detailed individual advice.
References
- NGWA Well Owners Guide. Westerville (OH): National Ground Water Association. 2021. https://wellowner.org/wp-content/uploads/2021/04/2021-WellOwners-Guide.pdf
- CDC-TABLE Drinking Water Treatment Technologies for Household Use. Atlanta (GA): US Center for Disease Control. 2008 Nov. https://www.cdc.gov/healthywater/pdf/drinking/Household_Water_Treatment.pdf
- Wellcare® information about Water Treatment. Washington (DC): Water Systems Council. [accessed 2 May 2023]. https://www.watersystemscouncil.org/download/wellcare_information_sheets/well_water_testing_&_treatment_information_sheets/Water-Treatment.pdf
- SCDHEC Drinking Water Common Water Quality Problems and Their Treatment. Columbia (SC): South Carolina Department of Health and Environmental Control 2013 Nov. https://scdhec.gov/sites/default/files/Library/CR-006453.pdf
Related Information
- HGIC 1901, Residential Drinking Water Wells: Well Components
- HGIC 1902, Residential Drinking Water Wells: Water Quality
- Be Well Informed Program (https://www.clemson.edu/extension/water/programs/be-well-informed.html)
Originally published 10/23
