The experience of water tasting noticeably metallic, often described as having a tinny or blood-like flavor, is a frequent complaint regarding tap water quality. This sensory change immediately raises questions about the water’s safety and source. The underlying cause is often a common, naturally occurring mineral issue.
Iron as the Source of the Metallic Flavor
The most frequent culprit behind a metallic taste is the presence of dissolved iron, an abundant element that easily seeps into groundwater supplies and wells. Iron exists in water in two primary forms: ferrous and ferric. Ferrous iron is the dissolved, soluble form, often called “clear-water iron.” This form leaves the water clear but imparts a strong metallic taste at concentrations as low as 0.3 parts per million (ppm).
Ferrous iron becomes visible when it reacts with dissolved oxygen in the air or with disinfectants like chlorine, causing it to oxidize and transform into ferric iron. This oxidized form is insoluble and appears as rust-colored particles, commonly known as “red-water iron.” While ferric iron causes discoloration and staining, the metallic flavor is more pronounced when the iron is still in its clear, dissolved ferrous state. This transformation explains why water might taste fine initially but develop a distinct flavor after sitting in a glass.
Metallic Tastes Not Caused by Iron
While iron is a primary source of the metallic flavor, other metals can also be responsible, often originating from the home’s plumbing. Copper, zinc, and manganese are common metals that can leach into the water supply, causing a similar undesirable taste. Zinc often comes from the corrosion of galvanized pipes, which have a protective zinc coating that degrades over time.
Copper enters the water from corroding copper pipes and fixtures, frequently resulting in blue or green staining in sinks and tubs along with the metallic flavor. The presence of these metals is exacerbated by water with a low pH, meaning the water is acidic. Acidic water is highly corrosive, actively dissolving metal ions from the internal surfaces of the pipes and fixtures, intensifying the metallic taste and increasing metal concentration.
Assessing Safety and Health Concerns
When water tastes like metal, the natural concern is whether it poses a health risk. High concentrations of iron are considered a nuisance contaminant, primarily causing aesthetic problems like staining and poor taste. Since the human body is not efficient at absorbing inorganic iron from water, it poses a low health risk.
However, a metallic taste can also signal the presence of more harmful contaminants, particularly copper and lead, which are serious health concerns. Copper can cause gastrointestinal distress at high levels. Lead, which may impart a metallic taste, is toxic to the nervous system and is unsafe at any concentration. Relying on taste alone is an insufficient method for assessing water safety.
Testing and Treating Metallic Water
The initial step in addressing metallic-tasting water is obtaining a professional water test. This comprehensive analysis should evaluate the concentration of iron, copper, zinc, and lead, alongside the water’s pH level and corrosivity. Knowing the specific contaminant and its concentration is the only way to determine the correct remediation strategy.
If the issue is high ferrous iron, the common treatment involves an oxidation-filtration system, which uses air or a chemical agent like chlorine to convert the dissolved ferrous iron into filterable ferric iron. This solid ferric particle is then easily trapped and removed by a media filter. For issues caused by low pH, the most effective solution is an acid neutralizing filter, which uses media like calcite or magnesia to raise the water’s pH, thereby reducing its corrosivity and preventing the leaching of metals like copper and zinc. If the metallic taste is noticeable only in the morning, flushing the tap for a few minutes clears out water that has been sitting in the pipes overnight.