The short answer: a copper water test measures how much copper is in the water at your tap, and on a private well that copper almost always comes from your own plumbing, not the aquifer. EPA uses two numbers: an action level of 1.3 mg/L, which is also its health goal, and a secondary (taste and staining) standard of 1.0 mg/L. Neither is enforced on a private well. How you sample matters as much as the number, because copper builds up while water sits in the pipes.
The Minnesota Department of Health (MDH, updated September 25, 2024) gives the well-owner version: "Copper is not usually found in the groundwater that feeds your well. Copper may enter your drinking water as it travels through your plumbing system." This page follows that chain: corrosive water, copper pipe, a first-draw result, and the fix.
Infant or someone with Wilson's disease in the house? MDH says people with Wilson's disease and "some infants (babies under one year old) are more sensitive to copper," and that testing "is important if an infant or someone with Wilson's disease drinks your tap water." It also says to use cold water for drinking, cooking and baby formula, because "hot water releases more copper from pipes than cold water." What level is acceptable for your family is a question for your doctor or health department.
The copper numbers on your report: 1.3 vs 1.0 mg/L
Copper has three federal numbers, and two of them are the same value. All three are written for public water systems.
| Number | What it is | What EPA says |
|---|---|---|
| 1.3 mg/L (1,300 µg/L) | Maximum contaminant level goal (MCLG) | "The level of a contaminant in drinking water below which there is no known or expected risk to health." Non-enforceable. |
| 1.3 mg/L (1,300 µg/L) | Action level, Lead and Copper Rule | "If more than 10% of tap water samples exceed the action level, water systems must take additional steps." |
| 1.0 mg/L (1,000 µg/L) | Secondary standard (SMCL) | Non-mandatory. Effects above it: "metallic taste; blue-green staining." |
The first two rows come from EPA's National Primary Drinking Water Regulations table (updated August 31, 2026), which lists copper with an MCLG of 1.3 mg/L, "TT" (treatment technique) instead of a maximum contaminant level, and "Action Level=1.3." The third is from EPA's secondary standards page (updated May 26, 2026); EPA says it "does not enforce" these.
That makes copper unusual. For lead, EPA's goal is zero and the action level is 0.015 mg/L. For copper the two match, and the staining line sits below both, so stained fixtures can come with water under the health number.
Watch the units. The University of Nebraska–Lincoln's extension guide Drinking Water: Copper (G1360, revised November 2013) notes that 1.3 mg/L "also can be expressed as 1.3 parts per million (ppm)." MDH writes it as 1,300 µg/L, where one µg/L is one part per billion. A report reading "1,450 µg/L" is over the line; "0.145 mg/L" is far under it.
For a private well these are yardsticks. Nebraska: "private well users may consider the EPA established action level of 1.3 ppm as a guideline in assessing the risk associated with their water supply." MDH states it as a health line: "Drinking water with more than 1,300 micrograms of copper per liter of water (µg/L) can be a health risk for everyone."
Did the 2024 Lead and Copper Rule Improvements change copper?
Not the copper number. As of November 3, 2026, EPA's pages say:
- The Lead and Copper Rule Improvements page (last updated December 29, 2025): "On October 8th, the EPA issued a final rule requiring drinking water systems across the country to identify and replace lead pipes within 10 years." It adds "more rigorous testing" and "a lower threshold requiring communities to take action to protect people from lead exposure in water." Its infographic is dated October 2024. The lower threshold is for lead.
- The regulations table footnote: "For copper, the action level is 1.3 mg/L, and for lead is 0.015 mg/L. *Beginning on the LCRI compliance date of November 1, 2027, systems must comply with the revised lead action level of 0.010 mg/L."
- The rule text, 40 CFR 141.80 (eCFR, up to date as of October 30, 2026): "The copper action level is exceeded if the 90th percentile concentration of copper ... is greater than 1.3 mg/L."
EPA's Lead and Copper Rule overview (updated January 2, 2026) dates the rule to 1991. Because it works on the 90th percentile, a utility can comply while some homes have high copper, and private wells sit outside it altogether. A 2024 Virginia Tech paper says these gaps "leave all private well owners and many residents and nonresidential building owners with municipal water at risk" of high copper release.
Where copper in well water comes from
From the plumbing, in nearly every case. Nebraska: "Copper rarely occurs naturally in the source water supply for drinking water systems. Most copper contamination takes place at some point in the water delivery system." EPA lists two sources: "Corrosion of household plumbing systems; erosion of natural deposits." MDH reports that in 1999 the Minnesota Pollution Control Agency "found that none of the 954 wells they tested in Minnesota had copper levels over the EPA action level." One state and one survey, but it fits.
Penn State Extension (updated May 29, 2025) gives the home test of which it is: "Copper and lead concentrations are usually highest in the first water out of the tap since this water has been in contact with the plumbing for a longer time. Metal concentrations from corrosion will decrease as water is flushed through the plumbing system. If this doesn't happen, the source of the metals is most likely your well water itself."
Corrosive water: low pH is only part of it
Copper pipe dissolves in corrosive water. Nebraska lists the causes: "low (less than 8.0) pH, high temperature, low total dissolved solids (TDS) content and high amounts of dissolved oxygen or carbon dioxide," and "naturally soft water is more corrosive than hard water because it is more acidic and has low TDS."
Look at that pH figure. Nebraska's list starts at "less than 8.0," well above EPA's 6.5 lower guideline. MDH says the same about its own state: "Although the pH of groundwater in Minnesota is normally high enough to prevent water from dissolving copper, there are other water qualities that may contribute to corrosion." A pH of 7.2 is inside EPA's range and still no guarantee for your pipes. Our guide to low pH well water covers pH and TDS; here the copper result is what counts.
Two household factors push copper up. Hot water, per MDH, and ion-exchange softening: Nebraska says "increased copper levels in water softened with ion exchange water softeners have been observed," because softening "can either prevent or dissolve the mineral scale," though it "can have other benefits that outweigh the negative effects." Weighing equipment? See water softener vs. water filter.
New copper is the riskiest copper
Here copper and lead part ways. With lead, old plumbing is the worry. With copper, it's often new plumbing, because the protective mineral coating inside the pipe takes time to form:
- MDH: "Plumbing systems with copper parts less than three years old usually have not had time to build up this protective coating."
- Nebraska: forming the lining "can take months to years."
- Kriss and Edwards (ACS ES&T Water, 2024): high copper release "is expected in new plumbing and may persist for days, months, years, or decades," and whether coatings form "depends on water chemistry." Their framework advises residents who find elevated copper in relatively new pipe to "temporarily avoid ingesting the water until pipes are >6 months old."
Some water hadn't built the coating years later. In one of their case studies, a home on a public system still had high copper years after a renovation, and lab pipe tests with that water found no protective scale "for up to 36 weeks."
Two well-specific triggers follow. MDH warns that a new well "may have different water characteristics than your old well," so its water "may dissolve copper from your plumbing." And a remodel or repair in copper resets the clock; Nebraska names homes with "remodeled, renovated or repaired water distribution systems" as the exception where copper runs higher.
| Question | Copper | Lead |
|---|---|---|
| Usual source in a well system | Copper pipe and fittings (MDH; Nebraska) | Brass, solder, pump parts, fixtures (see the lead water test page) |
| Riskier plumbing | New copper: under three years (MDH), or until scale forms | Older parts made before the "lead free" limits tightened (lead page) |
| Visible or tasteable? | Sometimes: EPA lists metallic taste and blue-green staining above 1.0 mg/L | No. EPA: "you cannot see, taste, or smell lead dissolved in water" |
| EPA health goal | 1.3 mg/L | Zero |
| EPA action level | 1.3 mg/L, unchanged by the LCRI | 0.015 mg/L; 0.010 mg/L from November 1, 2027 |
| Sample | The same pair: a first draw after at least six hours, plus a flushed sample | |
Lead quote: EPA's basic information on lead (updated June 18, 2026).
Blue-green stains, metallic taste and other signs
Copper is one of the few well-water metals that sometimes shows itself. EPA's secondary standards page: corrosion "of iron and copper, may stain household fixtures and impart objectionable metallic taste and red or blue-green color to the water supply." Penn State: copper "can cause bluish-green stains in sinks and a metallic taste to water, especially when water is in contact with pipes for several hours (overnight)." MDH adds "pinhole leaks, pitting in your pipes, or blue green stains on plumbing fixtures" as signs of corrosive water. In the Virginia Tech paper, one resident first suspected a problem after "noticing blue deposits in their icemaker and a green tint to their hair"; a lab later measured copper up to 3.88 mg/L there.
The signs only work one way. Nebraska: "Low concentrations of copper in drinking water may not noticeably alter the taste, color or smell of water." A clean sink doesn't rule copper out, and a stain doesn't give you the number. EPA's private-well table (updated February 26, 2026) lists "Stained plumbing fixtures, laundry" as a reason to test for "Iron, copper, manganese," and our smell, taste and stains guide sorts stain colors by cause.
Corrosive water rarely takes only one metal. MDH: "If you see signs of corrosive water, Lead in Drinking Water may also be problem." EPA's table pairs plumbing that contains lead with "pH, lead, copper."
How common is high copper in well water?
We found no national random survey of copper at private-well taps. The largest data set we found comes from Virginia: 2,146 samples that private-system owners, mostly on wells, submitted between March 2012 and November 2013 (Pieper et al., Journal of Water and Health, 2015). The authors report that "12% had elevated copper concentrations (≥1.3 mg/L) in the first draw," against 19% for lead.
EPA secondary standard 1.0 EPA action level 1.3
Show the numbers
| Item | Value | Note |
|---|---|---|
| Median | 0.153 mg/L | |
| Mean | 0.677 mg/L | |
| 90th percentile | 1.727 mg/L |
Homeowner-submitted samples (self-selected, not random). 12% were at or above 1.3 mg/L in the first draw. Source: Pieper, Krometis, Gallagher, Benham and Edwards, Incidence of waterborne lead in private drinking water systems in Virginia, Journal of Water and Health 13(3):897-908, 2015, Table 1, accessed 2026-11-03.
Half the homes were at or below 0.153 mg/L. The mean, 0.677 mg/L, was more than four times the median, so a minority of high results pulled it up. The 90th percentile was 1.727 mg/L. A public system "exceeds" the copper action level when its 90th percentile is above 1.3 mg/L, so if these homes were one water system, they would be over that line. That's our comparison, not the study's, and the samples weren't compliance samples: homeowners collected 250 mL after at least six hours of standing, not one liter.
Participation "was wholly voluntary and participants were therefore self-selected," the authors note, so these are the homes that chose to test. Labs certified in either state are on the Virginia and Minnesota pages.
Health effects: what EPA and state health departments say
Copper is a nutrient at small doses. Nebraska calls it "an essential micronutrient," and MDH says "eating or drinking copper does not usually cause illness in most healthy people." Above the action level, EPA's regulations table lists "Gastrointestinal distress" for short-term exposure and "Liver or kidney damage" for long-term exposure, and says "People with Wilson's Disease should consult their personal doctor if the amount of copper in their water exceeds the action level."
MDH's list adds "headaches, vomiting, diarrhea, stomach cramps, nausea," says high levels "may damage red blood cells," and that infants and people with Wilson's disease "may need water with an even lower level of copper to stay safe." Nebraska warns that high copper "may cause symptoms easily mistaken as flu or other illnesses," so symptoms "are not a reliable indication of it." The Virginia Tech authors name "some pets" among the sensitive.
If someone has symptoms, a liver condition or Wilson's disease, take the report, both samples included, to a doctor.
How to take a copper water test: first draw vs. flushed
Copper is measured in the same first-draw sample as lead. The lead water test page walks through EPA's collection steps; here is what's specific to copper.
First draw. Nebraska: "when water is stagnant and in contact with copper pipes, it will continue to dissolve copper," so the highest copper comes from water that "has sat motionless in the plumbing system ... for at least six hours." The federal rule for public systems, 40 CFR 141.86, requires one-liter samples that "have stood motionless ... for at least six hours," and "the first-liter sample must be analyzed for lead and copper." From November 1, 2027, the rule adds a fifth-liter sample at lead-service-line sites, analyzed for lead only. Copper is judged by the first liter, the water that sat inside the house.
Flushed. Nebraska calls it a "purged-line-sample," taken "after the tap has run for at least two minutes and the water has become noticeably colder." It "will most likely indicate the copper concentration in source water." Penn State runs the water one minute, then tests to make sure copper and lead "are reduced to safe concentrations." The flush tells you whether running the water works and whether copper comes from upstream.
- Use a lab certified for copper. Nebraska: "approval must be obtained for each specific contaminant." Ask the lab whether its certification covers copper.
- Follow the lab's sheet and write down how long the water sat and ran.
- Order copper with lead and pH. For a wider panel, see our guide to well water testing and the which-tests tool.
- Treat kits as screening. In the 2024 Virginia Tech comparison, the color tile strip had "the highest false negative rate of 30%." The test kits vs. lab guide covers that study.
- Time it after new copper plumbing (and again later), after switching to a new well, and after installing treatment. See how often to test well water for routine intervals.
Copper isn't a filter in our lab finder yet. Start from the certified labs list or your state under labs by state, and confirm copper is on the lab's certified list when you call.
Reading your copper result: a decision table
Read both samples from the same faucet together. Thresholds are EPA's; actions are credited to their source. For report terms such as "ND," see how to read a well water test report; the results checker compares a copper value with both EPA numbers.
| # | Your result | Likely meaning | Sensible next step |
|---|---|---|---|
| 1 | First draw at or below 1.0 mg/L | Under both EPA numbers | Keep the report. Retest after new copper plumbing, a new well or treatment changes. |
| 2 | First draw above 1.0, up to 1.3 mg/L | Above the taste-and-staining guideline, at or under the action level | Cold water for drinking and cooking (MDH); run the tap after water has stood (MDH, Penn State). Check pH and corrosivity. |
| 3 | First draw above 1.3 mg/L, flushed low | Copper picked up while water stands in the house plumbing | Flush before drinking and use cold water (MDH, Nebraska, Penn State). Consider a lasting fix below. Infant or Wilson's disease: ask a doctor or the health department. |
| 4 | Flushed sample still above 1.3 mg/L | Penn State: if metals don't drop, "the source of the metals is most likely your well water itself." In very new pipe, flushing can also fall short (Kriss and Edwards) | MDH: over 1,300 µg/L after running 30–60 seconds, "you may want to consider home water treatment." Ask your county or state health department to help find the source. |
| 5 | Copper high and lead detected | The same corrosive water attacking both metals | Follow the lead page's decision table; the lead flush result decides whether a neutralizer is an option. |
| 6 | Home kit reads high, or reads low despite blue-green stains | Strips missed high copper 30% of the time in one study | Confirm with a certified lab before buying treatment. |
Worked examples: two wells, two copper problems
Illustrative numbers, not real results.
House A: drilled well, kitchen and bath replumbed in copper 14 months ago. pH 7.4. First draw 2.1 mg/L; flushed (2 minutes, noticeably colder) 0.18 mg/L. That's row 3: above the 1.3 mg/L action level, more than twice the 1.0 mg/L line, and the flush brings it down. The pH is in EPA's range but under Nebraska's "less than 8.0," and the pipe is younger than the three years MDH mentions. Plan: run the cold tap before drinking, retest the pair in six months to see whether copper falls as the pipe ages, and look at corrosion control if it doesn't.
House B: dug well, 1970s house with copper throughout, a blue-green stain under the tub spout. pH 6.1. First draw 1.15 mg/L; flushed 0.6 mg/L; lead detected in the first draw. Copper alone is row 2, and the stain matches EPA's description above 1.0 mg/L. The lead result puts it in row 5 too, and lead drives the plan: cold, flushed water now, a pH and alkalinity test before choosing a neutralizer, then a retest of both metals after treatment.
Fixes, from stopgap to permanent
Copper fixes either remove copper at the tap you drink from or make the water less corrosive so the pipes stop releasing it.
| Option | What sources say | Limits |
|---|---|---|
| Run the water | MDH: at least 30–60 seconds if unused over six hours. Penn State: one minute, needed only if water sat at least one hour. Nebraska: until "as cold as it will get," which "could take up to two minutes or longer," at each faucet. | Check with a flushed sample. In one Virginia Tech case with new pipe, five minutes "was not always sufficient," leaving up to 1.5 mg/L. |
| Point-of-use reverse osmosis or distillation | Nebraska: reverse osmosis removes "approximately 85 percent" of copper, distillation "approximately 99 percent." Penn State also lists activated alumina. | One faucet. Look for an independent certification listing copper reduction for the exact model. |
| Whole-house neutralizer (low pH) | Nebraska: for water "corrosive because of neutral or low pH," a neutralizing filter that raises pH. See the pH guide. | Needs routine maintenance "or the corrosion protection will be lost" (Nebraska). Test pH and alkalinity first. |
| Phosphate corrosion inhibitor | Nebraska: where dissolved oxygen or carbon dioxide drive corrosion, "polyphosphates are often used," forming "a thin protective layer." Kriss and Edwards list orthophosphate dosing. | Cartridges or a feed pump. With a softener, some unsoftened water is bypassed because polyphosphates "need a small amount of hardness to work." |
| Replace copper pipe | Penn State: approved plastic pipe is "directly stamped with an 'NSF' (National Sanitation Foundation) seal on the side." Kriss and Edwards: stainless steel or plastic, "although costly." | A whole-house job. |
Nebraska: "It is highly recommended that one consult a water treatment professional" before a whole-house system. The treatment-by-result guide compares these with fixes for other results.
What the Virginia Tech case studies add
Kriss and Edwards followed two homes with new copper on a public system, so this is evidence about the chemistry, not wells in particular:
- Treatment may have to be permanent. A soda-ash feed raising the pH was "effective at quickly reducing" copper below the action level, but "when treatment was suspended copper concentrations increased back above the AL." The authors conclude "long-term treatment (>36 weeks or permanently) may be needed."
- Carbon didn't help. Granular activated carbon "was the least effective treatment, exhibiting no apparent effect." Penn State: carbon filters "are not recommended for copper and lead removal."
- Grounding is rarely the cause. Nebraska says grounding electrical equipment to pipes can "occasionally" increase corrosion and suggests an electrician. The Virginia Tech team writes that "grounding is rarely the cause of elevated copper in water" in their experience.
After any fix, retest copper, first draw and flushed. If you have a softener, tell the lab; the hard water guide covers softeners and new copper pipe.
Where to go from here
Stains, a metallic taste, new copper pipe or a new well are all reasons to order copper with lead and pH, as a first-draw and flushed pair, from a lab certified for copper. Where a result touches health, such as an infant on formula, ask your doctor or health department what it means for your household.
Questions people ask
What is a safe level of copper in drinking water?
Does copper in well water come from the well itself?
What causes blue-green stains in a sink or tub?
Do I need a first-draw sample for a copper water test?
Did the 2024 Lead and Copper Rule Improvements change the copper limit?
Can a water softener raise copper levels?
How long does new copper pipe release high copper?
- Minnesota Department of Health, Copper in Drinking Water (last updated 09/25/2024) (accessed 2026-11-03)
- U.S. EPA, National Primary Drinking Water Regulations (copper MCLG, action level and footnote 7; updated August 31, 2026) (accessed 2026-11-03)
- U.S. EPA, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals (updated May 26, 2026) (accessed 2026-11-03)
- U.S. EPA, Lead and Copper Rule Improvements (last updated December 29, 2025) (accessed 2026-11-03)
- U.S. EPA, Lead and Copper Rule (last updated January 2, 2026) (accessed 2026-11-03)
- 40 CFR 141.80, General requirements (eCFR, up to date as of 10/30/2026) (accessed 2026-11-03)
- 40 CFR 141.86, Monitoring requirements for lead and copper in tap water (Cornell LII) (accessed 2026-11-03)
- University of Nebraska-Lincoln Extension, Drinking Water: Copper, G1360 (Dvorak, Skipton, Woldt and Drda; revised November 2013) (accessed 2026-11-03)
- Penn State Extension, Corrosive Water Problems (updated May 29, 2025) (accessed 2026-11-03)
- Kriss and Edwards, Guidance for Residents Addressing Copper Problems in Drinking Water: Opportunities and Challenges, ACS ES&T Water 4(9):4175-4183, 2024 (PMC11406526) (accessed 2026-11-03)
- Pieper, Krometis, Gallagher, Benham and Edwards, Incidence of waterborne lead in private drinking water systems in Virginia, Journal of Water and Health 13(3):897-908, 2015 (accessed 2026-11-03)
- U.S. EPA, Protect Your Home's Water (updated February 26, 2026) (accessed 2026-11-03)
- U.S. EPA, Basic Information about Lead in Drinking Water (updated June 18, 2026) (accessed 2026-11-03)
Find a certified lab
Our state lists do not filter by this test yet. Ask the lab whether it is on its certificate.
Open the lab finder