Copper in Water

An essential mineral that becomes harmful when pipes corrode.

Copper is a mineral your body actually needs — in small amounts. In water, it’s a different story: elevated copper almost always means corrosive water is eating at copper plumbing, and enough of it causes stomach upset and, over time, liver and kidney stress. A blue-green stain around drains is often the visible clue.

What it is

Copper is an essential trace mineral at dietary levels but harmful in excess. Water with high copper often has a metallic taste and can leave blue-green staining on sinks, tubs, and fixtures.

How it gets into water

Corroded copper plumbing is the main source — typically when water is acidic (low pH) or has sat in pipes for hours. Industrial waste and natural groundwater deposits contribute in some areas. Because corrosion is the usual driver, high copper is often a symptom of a water chemistry problem worth solving, not just a copper problem.

What a result can tell you

The EPA action level is 1.3 mg/L. Readings above it — especially in first-draw morning water — point to active corrosion. Flushing the tap before use lowers short-term exposure; checking pH and alkalinity tells you whether the water itself is the cause. High results deserve lab confirmation and a look at treatment options.

What it can’t tell you

A strip can’t distinguish source — pipes versus supply — or measure your actual daily intake. Sudden stomach symptoms after drinking suspect water are worth mentioning to a healthcare provider, and infants’ formula should not be prepared with water known to run high in copper.