Copper in Private Drinking Water Wells

Copper is rarely found in the water coming directly from your well but can often occur because of corrosion from the plumbing system. If drinking water test results indicate an excess of copper, removal options include replacing copper pipes and fixtures; managing the water used for drinking and cooking by flushing water from the system before use, installing a treatment system, or using an alternative water source. If home treatment is necessary, treatment options include raising the water’s pH, ion exchange, reverse osmosis, and distillation.

The Maximum Contaminant Level Goal (MCLG) for copper in public drinking water supplies is 1.3 milligrams per liter (mg/l) as established by the EPA. An MCLG is a non-enforceable, health-based level. At copper levels below 1.3 mg/l, health problems are not likely. The MCLG of 1.3 mg/l is also the level at which public water systems are required to take actions to treat their water for copper.

Potential Health Effects

Copper is an essential nutrient that the body requires in very small amounts. However, drinking very high levels of copper can cause nausea, vomiting and diarrhea, and can damage your liver and kidneys. People with Wilsons disease (a rare inherited disease that causes the body to accumulate copper) may be more sensitive to the harmful effects of copper and should consult their health care provider if their drinking water is contaminated with copper.

Indications of Copper

At very high levels, copper can cause a bitter metallic taste in water and result in blue-green stains on plumbing fixtures.

Sources of Copper in Drinking Water

Copper piping and fittings are widely used in household plumbing. Most copper contamination in drinking water occurs within the plumbing system because of corrosion of the copper pipes and/or fittings.

The physical and chemical characteristics of water vary, including its corrosive properties. Private well owners should be concerned with the pH of their water supply. pH is an indicator of the acid or alkaline condition of water. The pH scale ranges from 0-14; 7 indicates the theoretical neutral point. Water with a pH value less than 7 indicates acidity and tends to be corrosive, while water with a value greater than 7 indicates alkalinity and tends to affect the taste of the water. Acidity or low pH is caused by natural geological conditions in the area. The optimal pH
range for drinking water is 6.5 – 8.5 as established by the EPA. For more information, please refer to our guidance about pH – Acidity of Private Drinking Water Wells.

Connecticut’s groundwater is typically acidic. In addition, water that is naturally soft is generally more corrosive than hard water because it is lower in alkalinity. Soft water has a lower concentration of dissolved minerals, especially calcium and magnesium.

When ion exchange water softeners are used to treat hard water or elevated levels of iron and manganese, it can result in the water being made more corrosive. These treatment units can decrease alkalinity and hardness and consequently increase the potential for increased corrosion of copper in the plumbing.

Testing for Copper in Private Drinking Water Wells

If you notice a metallic taste in your water or have blue/blue-green stains in sinks or plumbing fixtures, you should test your water for copper. To determine if copper is present, arrange to test your drinking water at a state certified laboratory. Follow the laboratory's instructions carefully to avoid contamination and to obtain a good sample. To evaluate the household’s highest level of copper exposure, collect a sample when water has remained motionless or stagnant in the plumbing system for at least six hours. When collecting the sample, collect the first flush of
water from the cold-water faucet with the aerator removed. Do not allow any water to run before collecting the sample. This is called a first-draw or first-flush sample. This first flush will contain the highest copper levels.

Interpreting Test Results

To interpret the test results, consider both the copper concentrations and the comparison between the first draw and flushed samples. If results show higher levels of copper in the first-draw sample than the flushed sample, the copper is most likely coming from corrosion of household plumbing components, such as copper pipes or fittings. On the other hand, if test results show nearly equal amounts of copper in both the first draw and flushed samples, the copper is probably coming from a plumbing source outside the house, such as the well pump.

Corrective Action

If water test results indicate elevated levels of copper are present in the drinking water, the first course of action is to identify the source. Where possible and cost-effective, eliminate the source by replacing the copper plumbing component(s) with approved plastic options. In some cases, this may be impractical and cost prohibitive.

In most cases, installing a treatment system or flushing water from the pipes before it is used (if water test results show this is an effect technique) may be a more realistic option.  A treatment system to adjust low pH and/or high corrosivity may be an option.  Other treatment systems to consider that are effective at reducing copper levels at the point of use include reverse osmosis, distillation, or ion exchange treatment with resin specifically designed to remove copper ions.  For point-of-entry or whole house-treatment, you can consider installing a calcite treatment system for pH adjustment.

For more information on these treatment options, please see the Publications entitled:

Regardless of the quality of any equipment purchased, it will not operate well unless maintained in accordance with the manufacturer’s recommendations. Keep a logbook to record equipment maintenance and repairs. Maintaining your treatment equipment may include periodic cleaning and the replacement of some components. Also consider any special installation requirements that may add to the equipment cost. Refer to our guidance Questions to Ask When Purchasing Home Water Treatment Equipment for more information.

Flushing the Pipes

One simple way to remove copper from tap water is to let the water run before using it for cooking or drinking whenever the household water remains unused for more than six (6) hours. This would include the times when you first get up in the morning or when you come home from work. The longer the water sits stagnant in your household pipes, the more copper it may contain. Flushing the tap means running the cold-water faucet until the water feels as cold as it can get or for a period of about 1 minute. Also, avoid cooking, drinking or preparing baby formula with water from the hot water faucet.  Hot water dissolves copper more easily than cold water. If you need hot water, draw water from the cold-water faucet and heat it on the stove or in the microwave.

IMPORTANT NOTE: Flushing is only a valid treatment option when test results from flushed water samples show little to no copper concentrations compared to the first flush or first draw samples.