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Cannabis Science 101: The Complex Chemistry of the Bong

February 11, 2016

What’s going on in that bong?

Seriously. What is the science behind the water pipe? Are those bubbles actually making your toke any healthier? It’s complicated.

A couple things are happening. Burning cannabis produces a smoke stream that contains all the things you want — activated THC, CBD, other cannabinoids and terpenes — and a lot of things you don’t, like hot smoke, tar, and fine particulate matter, a.k.a. ash.

Terpenes: The Flavors of Cannabis Aromatherapy

Tar” is a catch-all term for the hundreds of nasty compounds produced by cannabis combustion. Aside from nicotine, cannabis smoke is qualitatively similar to tobacco smoke, with a lot of polycyclic aromatic hydrocarbons (PAHs) you don’t want in your lungs. There is epidemiologic evidence that tobacco smokers who use a water pipe have a much lower incidence of cancer than those who smoke cigarettes or regular pipes. So clearly there’s some good filtration going on. (Too much cannabis smoking can harm the lungs in a number of ways, but despite decades spent looking for it, researchers have never found a link between cannabis smoking and lung cancer — a story for another day.)

The bong, a.k.a. water pipe, immediately cools the smoke by passing it through water, resulting in a smoother toke. The water also filters out any ash that might otherwise blow into your mouth or airway. There’s also a certain amount of tar filtration that goes on. That’s why the water eventually turns sickly brown.

That’s about the extent of agreement, though. “There’s a great debate about whether bongs actually filter effectively,” said Kenji Hobbs, manager at Uncle Ike’s Pot Shop in Seattle. “Studies in California have shown bongs filter more water-soluble psychoactive cannabinoids than tar and polycarbons, which means the user has to smoke more weed to get an effective high, because the tar-to-cannabinoid ration is now more skewed towards tar.”

Nobody’s sure exactly how much cannabinoid filtration is going on, though. “Those who are familiar with and work in cannabis extractions know that water, as a polar solvent, doesn’t do a good job of dissolving cannabinoids, terpenes, or waxes,” explained A.J. Fabrizio, director of research for Los Angeles-area medical cannabis company Terra Tech. This is why homebrew concentrate makers use non-polar solvents such as butane, not water, as a solvent. (We shouldn’t have to say this, but: Please don’t homebrew concentrates using solvents. It’s illegal and people could die. Try making rosin instead.)

How to Make Rosin

“Are you losing any cannabinoids or terpenes as the gas passes through water?” said Fabrizio. “Yes, but it’s negligible. The water will preferentially filter particulate matter and potentially solvate polar molecules, over the cannabinoids and terpenes, which have virtually zero water solubility.”

It’s not a one-way exchange, though. What’s in the water can also change the nature of the smoke. “If you’ve inhaled through dirty bong water, you know what happens,” said Fabrizio. “It tastes like dirty disgusting resin.” Further, “if the water has been chlorinated, that chlorine flavor will carry through.” That’s because the gas is absorbing denatured constituents from the dirty water, such as plant-based molecules that have been fully oxidized during combustion, and that exchange comes through the bubbles. It’s a two-way interaction. “This is why people talk about cleaning your bong — and it’s also important with dabbing too. You need to make sure that chamber and that water is pretty clean if you want to ensure an unadulterated flavor”

The gas-liquid exchange occurs only between the surface area of each bubble and the surrounding liquid. “Really big bubbles offer relatively low surface area to volume ratios,” Fabrizio explained. “A diffuser that produces a lot of smaller bubbles offer a relatively high surface area to volume ratio allowing for greater exchange between the gas and liquid,” and presumably a greater degree of filtration.

Does it make sense to use alcohol — vodka and such — in the chamber? “Not advised, or safe,” cautioned Fabrizio. “Huffing alcohol fumes is toxic.” In addition, cannabinoids and terpenes are more likely to dissolve in alcohol than water, so you’re essentially stripping the smoke of its more desirable compounds. It’s also a nasty inhalation experience, as our Leafly testing team recently found in Leafly’s bong water experiment.

The Leafly Bong Experiment: What Happens When You Replace Bong Water with Other Liquids?

Very few studies have been done on cannabis and water pipes, and those studies have turned up curious data. That “California study” Hobbs, of Uncle Ike’s, referred to was carried out in the mid-1990s by Dale Gieringer, NORML’s California state coordinator, in association with MAPS, the Multidisciplinary Association for Psychedelic Studies. They wanted to test the effectiveness of bongs, joints, and vaporizers. They found that unfiltered joints actually outperformed the bong — by quite a lot. The bong, they reported, “produced 30% more tar per cannabinoids than the unfiltered joint.” The vaporizer — at the time, one of the earliest on the market — vastly outperformed them all, delivering far more cannabinoids per unit of tar.

One of the problems, Gieringer wrote back then, was that the researchers were forced to use poor-quality marijuana supplied by the National Institute on Drug Abuse, with THC levels of 2.3 percent. (Today’s legal cannabis typically ranges between 15 to 25 percent THC.) That little detail matters, because it requires consumers to burn more leaf – and inhale more unwanted byproducts – to obtain the desired level of cannabinoid intake. “We were surprised and a little disappointed at the time,” Gieringer recalled last week. “But we learned that vaporization looked good, even with what was at the time a really crude device.”

Also in the mid-1990s, University of Wisconsin pharmacologist Nicholas V. Cozzi penned a literature review of past water pipe studies, mostly from the 1960s and 1970s. He found that the devices “can be effective in removing components from marijuana smoke that are known toxicants, while allowing the THC to pass through relatively intact.”

The conflicting results were puzzling, to say the least, and pointed out the need for further study. Unfortunately, further water pipe studies were not forthcoming. Researchers instead focused their attention on studies of vaporizers as a more healthy vehicle for cannabis dosing. In the meantime, Gieringer had a tip for those looking for a healthier form of intake: Consider more cannabinoids per unit of vegetable matter.

“The easiest way for most smokers to avoid harmful smoke toxins,” he wrote, “may be simply to smoke stronger marijuana.”

How Does a Bong Work? A Guide to the Water Pipe

  • lovingc

    Try Kahlua it makes it taste good and keeps the sludge together making for an easier clean out.

  • Steve Mc coy

    These bongs we have in Bakersfield,ca are the best in the market.

    • Jessy

      Nice pitch

  • James Ray

    I am looking for the possible uses of bong water; is there any way to turn that nasty stuff into a positive thing? does it kill bad cells of any kind? Is it a bug killer? Does it help plants grow? Will it remove laugh lines?
    I am open to suggestions and ideas.

    • Jane

      I would try it in the garden – I know a lot of people drop cigarette butts in their gardens to deter pests. Bongwater might do the same thing.

      • Colton Smith

        Lol cigarette butts in the garden?


        Who wants a baby carrot? Oh wait, that’s a cigarette butt…

  • ChampIsHere

    Need to get me a vape

  • Evan Heiser

    the volcano has risen.

  • Fantasy2u

    I have both vape and bong – in the house i use the bong 3 chambers last one holds ice is a smooth smoke – outside working in yard etc. i use the vape. I like them both.

  • Willnot Censor

    Why do you think The THC goes down when vapor is passed through water? Water cools the THC etc below its vape/boil temp. Vapor returns to oil/liquid form & Drops out of vapor stream. The more diffuser’s you have, the more THC you lose. Look at and look at the Water Filtration section. I look forward to your comments.

  • Dean Lee

    I didn’t read all of this, but within the first 2 paragraphs I noticed some incorrect information. I know not all will be incorrect but I suggest people do their research on the subject. Even after decades of smoking cannabis, it will have no ill effect on your lungs or any other part of your body.

    • Jessy

      Youre obviously not a kronic. Smoke is smoke to the lungs. Every piece of glass I have, has gone pitch black from the smoke passing by. The **** you think it’s doing to your lungs.

      • Kathy Vosgerichian

        No ,if you blow the weed smoke through a tissue ,it will barely show any color at all ,just a very very pale yellow,that because the tar from cannabis does not adhere to the lungs the way cigs does,Youll noyice little brown bits in the mucus you spit out .Thats the resin coming out. Do the tissue test with a cigarette smoker and the tissue is dirty disgusting brown.

        • Karsten Guth

          Umm I’ve blown smoke through dryer sheets for years lol so let me tell you from first hand experience they get brown, sticky, and very gross. I’m sure cigarettes would be much worse but just saying it is not just a pale yellow color.

  • Willnot Censor

    I am sorry to have to be the bearer of bad news. Look at and look at the Water Filtration section.
    After you have read the information and article links, feel free to contact me with your thoughts.

    • paul helssom

      If you must post advertising masquerading as facts please do it elsewhere.

  • Grass Chief

    Bong is an art of smoking weed. Like the incomparable ideas about the chemistry of bong shared here. A perfect bong can make the smoking really enjoyable. Great post.

  • berlioz

    Isn’t it better to just bake your weed into a nice meal and not worry about having gear to upkeep and worry about?

    • COGSx86

      what do you do in between?