Nickel is a naturally occurring element widely distributed in the earth’s crust. This silvery-white metal is often used in alloys due to its resistance to corrosion and heat. While trace amounts are generally harmless, elevated concentrations in drinking water can raise questions about water quality and safety. Determining the level of nickel in your water is the first step toward safeguarding your home’s supply.
Sources of Nickel Contamination and Health Concerns
Nickel enters water supplies through both natural and human activities. Naturally, it leaches into groundwater from the erosion of nickel ore-bearing rocks and soil deposits. Water with a lower pH (more acidic) can accelerate this dissolution process, leading to higher concentrations in certain sources.
A more common source in residential settings is corrosion or leaching from household plumbing and fixtures. Nickel is frequently used in nickel-plated taps, faucets, and stainless steel components in pipes and well materials. Water that stands motionless in contact with these materials, such as overnight, often shows a temporary spike in nickel concentration.
Long-term exposure to high levels of nickel through drinking water is primarily linked to non-cancer health issues. The most widely recognized effect is allergic contact dermatitis, causing skin irritation and rashes in sensitive individuals. Animal studies suggest that chronic, high-level oral exposure can potentially affect the kidneys and liver. While certain nickel compounds are classified as human carcinogens via inhalation, no definitive link has been established between oral ingestion and cancer risk in humans.
Choosing Your Testing Method
Accurately determining the concentration of nickel requires choosing between home screening and professional laboratory analysis. Do-it-yourself (DIY) test kits are readily available and provide a simple, immediate indication of nickel presence. These kits are often semi-quantitative, suggesting a range or presence/absence, but they lack the precision required for a definitive safety assessment.
For reliable, quantitative results, professional laboratory testing is necessary. This involves submitting a water sample to a certified laboratory, preferably one accredited by the state or the Environmental Protection Agency (EPA). Labs use advanced techniques like Inductively Coupled Plasma Mass Spectrometry (ICP-MS) or Atomic Absorption Spectrophotometry (AAS) to measure nickel at very low parts-per-billion levels.
The sample collection process is highly specific and must follow the lab’s instructions exactly, especially concerning whether the sample should be taken from a flushed line or standing water. Professional testing provides a precise number, typically in micrograms per liter (\(\mu g/L\)). This precise measurement is essential for comparison against regulatory standards. This comprehensive analysis eliminates the uncertainty associated with home kits and confirms compliance with health advisories.
Interpreting Regulatory Safety Levels
Once you receive a lab report, the results must be compared against established health standards to determine if action is warranted. The World Health Organization (WHO) has set a guideline for nickel in drinking water at \(70 \mu g/L\). In the United States, the EPA’s Maximum Contaminant Level (MCL) for nickel was remanded in 1995 due to procedural issues.
Despite the remanded status of the enforceable MCL, the EPA maintains a lifetime health advisory level of \(100 \mu g/L\) (\(0.1 mg/L\)). This advisory represents the concentration of nickel not expected to cause adverse non-cancer health effects over a person’s lifetime. If test results are below \(100 \mu g/L\), the level is generally not a public health concern based on federal guidelines. A reading that exceeds this advisory level indicates a need for remediation, though results below the limit may still warrant action if household members have nickel allergies.
A result indicating a “detectable” level is not automatically a “dangerous” one. The specific concentration must be the focus of the interpretation.
Options for Nickel Removal
If testing confirms nickel levels above the EPA’s lifetime health advisory, several treatment options are effective for residential water systems. Reverse osmosis (RO) is one of the most efficient methods, using a semi-permeable membrane to physically filter out up to 99% of heavy metal ions, including nickel. RO systems are typically installed at the point-of-use, such as under the kitchen sink, to treat water used for drinking and cooking.
Another viable strategy is ion exchange, where nickel ions are chemically exchanged for harmless ions like sodium or potassium as the water passes through a specialized resin. This method is often used in whole-house filtration systems. Activated alumina filtration can also contribute to nickel reduction, though it is usually less effective than RO or dedicated ion exchange systems. Following the installation of any treatment system, retesting the water is necessary to confirm that nickel levels have been successfully reduced.