Copper in Water: Find the Cause, Fix It

Signs of copper in your water

Penn State Extension links these symptoms to corrosive water that is dissolving metal plumbing [Penn State Extension: Common drinking water problems and solutions] [Penn State Extension: Corrosive water problems]:

• Blue-green stains on sinks, tubs, faucets and shower walls
• A metallic or bitter taste, especially in water that has sat in the pipes overnight
• Pinhole leaks in copper pipe in more advanced cases

These are general signs, not a diagnosis. A water test confirms it.

Where copper comes from

EPA lists the sources of copper in drinking water as corrosion of household plumbing systems and erosion of natural deposits [EPA: National Primary Drinking Water Regulations]. In most homes it’s the first one: water with a low (acidic) pH, or water that is otherwise corrosive, picks up copper from pipes and fittings [Penn State Extension: Corrosive water problems]. In some private wells, copper can also come from the groundwater itself. See low pH (acidic) water for more on corrosive water.

What the standards say

EPA regulates copper with a treatment technique under its lead and copper rules, with an action level of 1.3 mg/L at the tap [EPA: National Primary Drinking Water Regulations]. California uses the same 1.3 mg/L action level [State Water Board: California and federal MCLs (Sept 2024)]. According to EPA, short-term exposure above the action level can cause gastrointestinal distress, long-term exposure can cause liver or kidney damage, and people with Wilson’s disease should consult their doctor if the copper in their water exceeds the action level [EPA: National Primary Drinking Water Regulations].

Those rules apply to public water systems. If you’re on a private well, testing is up to you [CDC: Guidelines for testing well water].

How we test for copper

1. Free in-home water test. We come to you and check the basics at your tap: hardness, precipitation, chlorine and soap testing, and more, depending on what you’re noticing.
2. Lab test where it matters. For anything with a health-based limit, we arrange a state-certified lab test and walk you through the report in plain English.
3. A written, no-pressure estimate for only what your water calls for. Sometimes that’s nothing at all.
4. Tested before, tested after. Once your system is in, we test again, with a follow-up lab test for health-related contaminants. If the results don’t match what we showed you, we adjust it at no charge.

How we treat it

Copper is usually a symptom, so we treat the cause first and choose the rest from your test results:

• pH correction for acidic water. A calcite or Corosex neutralizer raises the pH where water enters the house, so it stops dissolving the copper plumbing downstream. See low pH water.
• Reverse osmosis for drinking water. A under-sink (point-of-use) reverse osmosis (RO) system at the kitchen sink reduces copper and other dissolved metals in the water you drink and cook with.
• Ion exchange where your results call for whole-house treatment, sized from your test.
• Specialty (selective) media for less common situations, chosen from your lab results.

Every system is built with NSF-certified components, and we test again after install so you can see the results.

What treatment gives you

• No more blue-green stains on sinks, tubs and fixtures.
• Better-tasting water without the metallic edge.
• Protected copper plumbing, water heater and fixtures when the cause is corrosive water.
• Peace of mind, backed by a test after install.

Copper testing near you

We test and treat water across the corridor: Manteca · Lathrop · Stockton · Patterson · Hughson · Turlock · Modesto.