Well Water Testing
Recent studies by the United States Geological Survey (USGS) and others have found a prevalence of high levels of arsenic and uranium in well water in Connecticut. Long-term exposure to arsenic and uranium can have major health impacts such as compromised immune systems, cancer, kidney damage and developmental issues in children. It is therefore very important that residents test their well water periodically to ensure that it remains safe for consumption.
In terms of regulation, there is no federal or state requirement for private well owners to routinely test their water. Local health directors may require routine testing only if there is known contamination in the area. Additionally, the only time testing results are reported to local health departments is when the test is performed in conjunction with a property transaction or new construction. Consequently, information on well water quality can be incomplete and outdated. The only way to know your well water quality for certain is to have it tested yourself.
To help residents navigate the resources available to them, WestCOG has developed this webpage to provide residents with updated information on well water testing and affordable testing and treatment options. See below for recommendations concerning testing parameters and testing frequencies. .
For more information on well water testing in Connecticut, visit the Department of Public Health (DPH) Private Wells Program website or the Environmental Protection Agency (EPA) Private Drinking Water Wells website listed below.
Recommended Testing
Based on the recommendations of DPH and the Water Planning Council Advisory Group (WPCAG), WestCOG has developed the following list of recommended testing parameters. Additional parameters such as heavy metals, PFAs, pesticides and herbicides can be tested for upon request but are typically only a concern if the well is located near or down gradient from former industrial or intensive agricultural sites.
| Parameter | Testing Frequency | Drinking Water Standard | Common Treatment Methods |
| Total Coliform Bacteria | Every year | None Present | Shock Chlorination; UV light |
| Nitrate-Nitrogen | Every year | 10 mg/L | Reverse Osmosis; Anion Exchange; Distillation |
| Nitrite-Nitrogen | Every year | 1 mg/L | Reverse Osmosis; Anion Exchange; Distillation |
| pH | Every year | 6.5-8.5 SU | Acid Neutralizing Filter; Soda Ash Injection |
| Odor | Every year | Filtration | |
| Sodium | Every year | 100 mg/L | Reverse Osmosis; Distillation |
| Chloride | Every year | 250 mg/L | Reverse Osmosis; Distillation |
| Hardness | Every year | 0-60 Soft; 61-120 Mod Hard; 121-180 Hard; >181 Very Hard | Water Softener |
| Apparent Color | Every year | < 15 SU | Filtration |
| Sulfate | Every year | 250 mg/L | Reverse Osmosis; Anion Exchange; Distillation |
| Turbidity | Every year | < 5 SU | Filtration |
| Iron | Every year | 0.3 mg/L | Iron Filtration |
| Manganese | Every year | 0.03 mg/L (Aesthetic based) 0.3 mg/L (Health based) | Oxidizing/Greensand Filter; Water Softener (low concentration) |
| Lead | Every 3-5 years | 15 ppb | Reverse Osmosis; Distillation |
| Arsenic | Every 5 years | 0.01 mg/L | Reverse Osmosis; Anion Exchange; Distillation; Oxidizing/Greensand Filter |
| Uranium | Every 5 years | 0.03 mg/L | Reverse Osmosis; Anion Exchange; Distillation |
| Radon | Every 5 years | 4,000 pCi/L | Aeration; Granular Activated Treatment |
| Fluoride | Every 5 years | 2.0 mg/L | Reverse Osmosis; Distillation; Activated Alumina Filters; Bone Charcoal Carbon Filters |
| Volatile Organic Compounds (VOCs) | At least Once | Varies by compound | Varies by compound |
Due to groundwater flow, DPH strongly encourages residents to follow its guidance on testing frequency. Even if well water tests negative for contaminates one year, it can potentially become contaminated by water flowing down gradient from a remote source.
The Drinking Water Standards are derived from the EPA Maximum Contaminant Levels (MCLs), which specify the maximum contaminant concentration deemed acceptable in public drinking water by the EPA. Some of these standards are set based on aesthetics, while others are set based on health risks.
More information about recommended testing can be found from DPH and the EPA.