When tap water develops a flavor reminiscent of old pennies, blood, or a general bitter sensation, it is commonly described as having a metallic taste. This unusual sensory experience is a signal that trace amounts of certain substances, usually metals, have entered the water supply. Understanding the causes of this metallic flavor and whether it indicates a serious health risk is the primary concern for any homeowner. The presence of a metallic taste does not automatically mean the water is unsafe, but it does warrant further investigation into the source of the contamination.
Common Causes of Metallic Taste
The most frequent culprits behind water that tastes metallic are aesthetic contaminants. Iron and zinc are two common metals that contribute to this distinct flavor. Iron particles often enter the water from corroded, rusting pipes, especially in older homes or from well water sources, which is sometimes evident by a reddish-brown tint or staining.
Zinc is another metal that can leach into the water, particularly from galvanized steel pipes, which are coated with zinc to prevent rust. Over many years, this protective coating can break down, releasing zinc into the water. The underlying cause of metal leaching is often water corrosivity, which is measured by its pH level.
When water has a low pH (more acidic), it can dissolve metals from plumbing materials at a faster rate. A pH below the neutral level of 7 can accelerate the corrosion of pipes made of iron, zinc, or copper. This chemical process introduces the metallic ions into the water, resulting in the unpleasant taste. The presence of these metals is a strong indication of plumbing corrosion that could lead to more serious issues.
Determining if the Taste Poses a Health Risk
While iron and zinc primarily create an unpleasant taste, a metallic flavor can also signal the presence of hazardous contaminants like copper. High levels of copper impart a bitter or metallic taste and can cause acute health effects such as gastrointestinal distress, including nausea and diarrhea. Long-term exposure to high copper concentrations can potentially lead to liver or kidney damage.
The Environmental Protection Agency (EPA) addresses this distinction by setting two types of standards: a Primary Maximum Contaminant Level for health threats and a Secondary Maximum Contaminant Level for aesthetic issues like taste. Copper is regulated under the Lead and Copper Rule, with an action level of 1.3 milligrams per liter (mg/L). This level triggers corrective action by the water system if exceeded in a significant percentage of homes.
A more concerning metal is lead, which is highly toxic and can cause serious health issues, especially for children. Lead is often tasteless and odorless, meaning the absence of a metallic flavor is not a guarantee of safety. The presence of a metallic taste from another source, however, does confirm that corrosive water conditions exist, which significantly increases the chance of lead leaching from older lead service lines or lead-containing solder. The EPA has set a maximum contaminant level goal of zero for lead, underscoring its danger.
Steps for Testing and Remediation
If you notice a metallic taste, flush your plumbing by running the cold water for a few minutes, especially after periods of inactivity, as standing water allows metals to leach more readily. If the metallic taste is only present in the hot water, the issue is likely isolated to the water heater, which may be corroding internally. Professional water testing is necessary to determine the exact nature and severity of the problem.
A certified laboratory test provides a precise analysis of metal concentrations, which can be compared to EPA health standards. Testing should focus on specific metals like copper and lead, as well as checking the water’s pH level to assess corrosivity. If the test results indicate hazardous levels of a contaminant, such as lead, the water utility or local health department should be contacted immediately for guidance.
For remediation, if the issue is aesthetic, point-of-use filtration systems like activated carbon filters can effectively absorb contaminants and improve taste. If testing reveals high concentrations of health-related contaminants, more advanced treatment like a reverse osmosis system may be appropriate, as these are highly effective at removing heavy metals. For issues stemming from the service line, the water system may be required to implement corrosion control measures or replace lead lines entirely.