Copper Water Bottle Benefits: What the Evidence Shows

What a copper bottle actually does to water

Copper dissolves into water slowly, as copper ions. Copper is antibacterial, though the researchers behind the main study say exactly how it acts on bacteria isn’t fully understood [1]. The dissolved copper is also the copper you end up drinking.

Studies have measured how much copper leaches into the water. Groundwater kept in copper pots for 16 hours held 0.177 mg of copper per liter (177 parts per billion) [1]. Tap water kept in a copper container held 0.327 mg/L after 12 hours and kept rising, to 0.813 mg/L after 7 days [5]. An earlier study found under 0.475 mg/L after a night [2]. So the longer water sits, the more copper it carries. Acidic water picks up more copper too, according to the US Agency for Toxic Substances and Disease Registry (ATSDR) and the WHO [12, 13]. (Our copper guide puts these numbers next to the safety limits in a chart.)

Copper itself is an essential trace mineral. Your body uses it in enzymes for energy production, iron metabolism and connective tissue, and in pigmentation and immune function, according to the NIH [10]. None of that means copper water improves those things, and that gap is where most of the marketing lives.

Benefits of copper water bottle use, claim by claim

Here are the benefits printed on bottle listings and brand blogs, next to the strongest evidence we could find for each.

Kills bacteria in stored water: shown in lab studies

Of everything on the list, this is the only claim the data support. In a 2009 study, water contaminated with E. coli, Salmonella Typhi and Vibrio cholerae was kept overnight in a copper pot, or in a glass container with a copper coil, and none of the bacteria could be recovered afterward [2]. A 2012 follow-up added six diarrhea-causing bacteria to groundwater (about 500 per milliliter) and stored it in copper pots for 16 hours at room temperature. Again, none could be recovered, even after the researchers tried to grow them in enrichment broth [1].

Copper surfaces are antimicrobial in general. The US EPA registered copper as the first solid antimicrobial material, and bacteria on copper surfaces die fast, at a rate of at least 7 to 8 logs per hour (a log is a tenfold drop) [4].

The researchers themselves list the limits. They couldn’t confirm whether the bacteria had died or entered a “viable but non-culturable” state, where cells stop growing on lab media but are still alive. They also wrote that the method needs testing under real conditions in households [1]. A separate study found that what is dissolved in the water changes how well a copper vessel works against E. coli [3]. So does copper purify water? In the lab, against these bacteria, it worked. We found no study showing that a copper bottle makes unsafe water safe to drink at home, so it is not a replacement for treated water.

Digestion, immunity and weight loss: no human studies

These three show up on most brand pages. We found no clinical trial, and no observational study, that tested whether drinking copper-stored water changes digestion, immune function or body weight. Copper does play a part in the immune system, as the NIH notes [10], but in a two-month trial extra copper in drinking water didn’t change blood markers of copper status, which the authors read as the body regulating its copper well [9]. Testing these claims would take a clinical trial that randomly gives some people copper water and others ordinary water, then compares their digestion, immunity or weight. The randomized copper-water trials we found (below) only looked for stomach upset.

Skin, thyroid and arthritis: no human studies of copper water

Copper is involved in pigmentation and connective tissue, which is where the melanin and collagen claims start [10]. Getting from “copper is involved” to “copper water improves your skin” skips every step that would need evidence. The same goes for thyroid balance and joint pain. We found no published study of copper-stored water and any of these outcomes.

“Alkaline” copper water: measured, and it isn’t

Unlike the others, this one is easy to measure, and two studies measured it. In the 2012 study the water’s pH went from 7.83 to 7.93 [1]. In the 2022 study tap water started at pH 7.02 and stayed between 6.97 and 7.16 over 7 days, which the authors describe as neutral [5]. A shift of a tenth of a unit or so, in either direction, isn’t the alkaline water sellers promise.

Do you need the extra copper?

Probably not. Adults need 900 micrograms (0.9 mg) of copper a day, and US adults already average 1.1 mg (women) to 1.4 mg (men) from food alone, according to the NIH, which also says copper deficiency is uncommon [10]. A liter of copper-stored water adds roughly 0.18 to 0.81 mg on top of that.

The only human trials of copper in drinking water we found were safety trials

Search the medical literature for people drinking copper in their water and you find one group of studies. They were looking for harm. Researchers at the University of Chile’s Institute of Nutrition and Food Technology, working with teams in other countries, gave healthy adults water with copper sulfate added at set levels and recorded stomach symptoms.

• In 2001, 179 adults at three sites drank 200 mL doses at 0, 2, 4, 6 or 8 mg of copper per liter. Nausea, usually within the first 15 minutes, was the main effect. Significantly more people reported symptoms at 6 and 8 mg/L, which made 4 mg/L the highest level with no added effect [6].
• In 2003, a trial of 269 women at four sites confirmed the same no-effect level, 4 mg/L [7].
• In a two-month community trial of 1,365 adults drinking water at under 0.01, 2, 4 or 6 mg/L, stomach symptoms rose with the copper level. In the first week the rise was significant from 4 mg/L in women and from 6 mg/L in men [8].
• Blood tests in part of that group found no link between copper intake and blood markers of copper load [9].

The copper levels measured in copper-stored water, 0.18 to 0.81 mg/L, are about 5 to 22 times below 4 mg/L, the level at which the two single-dose trials saw no effect. In the two-month trial, women first reported more symptoms at 4 mg/L, so the margin is still wide but not unlimited. What none of these trials asked is whether the copper made anyone healthier.

Copper water side effects and who should skip it

Too much copper in drinking water can cause nausea, vomiting, stomach pain and diarrhea, according to ATSDR [12]. Over the long term, excess copper can damage the liver and kidneys [10, 11, 12]. Copper toxicity is rare in healthy people, the NIH says, but it has been reported in people whose drinking water picked up high copper levels while standing in copper pipes and fixtures [10].

Who should skip copper water

• People with Wilson disease. It’s a rare inherited disorder in which the body can’t clear copper properly, so it builds up, and the NIH, EPA and ATSDR all flag it [10, 11, 12].
• Babies. The NIH sets no upper limit for infants and says their copper should come only from breast milk, formula and food [10].
• Toddlers and young children. The NIH upper limit is 1 mg a day at ages 1 to 3 and 3 mg at ages 4 to 8, so the margin is much smaller than for adults [10].
• Anyone a doctor has told to limit copper.

Acidity is another way to push the dose up. Acidic water draws more copper out of copper pipes, according to ATSDR and the WHO [12, 13], so keep lemon water, juice and other acidic drinks out of an unlined copper bottle.

If you decide to try copper water

• Use plain water only, and empty the bottle each day. Copper in stored water kept rising over 7 days [5].
• Make sure the inside is bare copper. A bottle that’s lined or lacquered inside keeps the water off the metal, so check before you buy a pure copper water bottle.
• See the copper guide linked above for how long to leave water in it, what else can go in it and how to clean it.

The bottom line

A copper bottle is a durable, reusable way to carry plain water, and in lab tests, bacteria added to water stored in copper couldn’t be recovered afterward. We found no human study for any other benefit on the label. If you’re a healthy adult and you like the ritual, it’s a low-risk habit. Don’t drink it for your digestion, your weight or your skin, and keep it away from babies, toddlers and anyone with Wilson disease.

Copper water bottle benefits FAQ

Sources and how we checked

We read the studies (full text where open, otherwise the abstract) and official fact sheets listed below. Every number on this page comes from them or is worked out from them. We didn’t test bottles ourselves. This page is general information, not medical advice.