What's the Deal With Downstems?

by Julia A.

If you’re a true purveyor of pipes, than you can go on and on about the different types of percolators, styles of water pipes, and probably boast quite a pipe collection yourself. Of all the factors in your water pipe, a tiny piece of glass might actually be the most important: downstems play a huge role in the quality of your smoke, and knowing what’s in a downstem can help you make the right purchase or upgrade for your pipe. Whether you’re just looking to improve your current pipe, replace a broken downstem, or understand if it’s necessary for your pipe to have one, this guide to downstems will answer all of your questions and prepare you for any downstem situation.

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What is a downstem?

A downstem is a long piece of glass that extends from the bowl of a bong into the water in the bong’s chamber. It helps smoke travel from the bowl of the bong into the water. Many downstems also feature slits in the glass that percolate and diffuse the smoke to enhance the smoke’s flavor.

You’ve probably seen a downstem before and just didn’t know the name. That long, skinny piece of glass that transfers smoke from the bowl into the bong’s base is a downstem! They almost always come with your bong when you first purchase it, and they’re usually attached to a bowl.

What are downstems for?

Without a downstem, your smoke would go right from the bowl into the bong, and it may not even reach the water--it’d just float into the neck and eventually up into the mouthpiece. A downstem ensures that all of your smoke is filtered through water before you inhale--without it, your smoke would taste like it came from a dry hand pipe.

Fixed Downstems:

These downstems are built right into your pipe. They’re super easy to use and require no setup--just pack your herb and go! However, if they break, you can’t easily replace these downstems and will most likely need to buy a new pipe. These are more common in bubblers that have downstems, as they are not easily accessible from the outside.

Removable Downstems:

Removable downstems are more common in bongs since they’re easy to take out and remove from the bowl. Most people like removable downstems because they’re easy to clean, and if they ever break, it’s cheap to order a new one (or have some backups on hand) and stick it right in. Sometimes, downstems get clogged with resin and other particulates over time, so it’s good to replace them when they’re showing signs of overuse.

What are downstems made of?

Downstems can be made of any glass, but like bongs, the gold standard of downstem construction is borosilicate glass. As we’ve expounded in another post on borosilicate glass, this type of glass is ideal for making pipes out of: it’s the most durable, heat-resistant type of glass on the planet. It’s also considered the purest: many glasses have toxic materials in them that aren’t safe to use for smoking at high temperatures, but borosilicate is completely non-toxic and safe for smoking. It’s also pretty easy to clean compared to other glasses.

The newcomer in the downstem game is silicone. As a response to how often we crack and drop our downstems, ELEV8 has stepped it up with new unbreakable, bendable, bold-colored silicone downstems.

Does every pipe have a downstem?

No. Really, almost any pipe that’s not a bong won’t have a downstem. Not all water pipes have a downstem either: dab rigs, which require less diffusion than dry-herb bongs, don’t always need a downstem since the vapor from concentrates is already so fine compared to harsher smoke from dry herb.

There are stemless water pipes: you’ll often see these with 90 degree pipes, like dab rigs, or pipes that have a built in connection from the bowl straight to the percolator for more direct, concentrated diffusion. You’ll know that these pipes don’t have a downstem as they’ll usually be called a stemless water pipe, like this masterpiece from GRAV Labs.

How do I clean a downstem?

Cleaning your downstem is much like cleaning your other glass pipes: for removable downstems, you can place them in a solution of rubbing alcohol and salt. Let the downstem soak for at least a few hours, and them remove. If your downstem is particularly dirty, you can do two soaks to really get the grime out.

Fixed downstems are more difficult to clean, but it’s not impossible: of course, it always helps if you can run water through your bong after each smoke sesh, as preventative care is the best way to keep your bong looking like new. Every week or so, try to get into the downstem with some cotton swabs and get any chunks of resin or ash that might be sitting inside the downstem. You can also fill your bong with isopropyl alcohol and salt, and let the mixture sit in your bong for a few hours. After the internal glass has soaked, seal off the joint and mouthpiece with your fingers, and give it a few vigorous shakes--not enough to break the downstem or percs inside, but something to push the solution around. If you combine these cleaning methods, you’ll be able to increase the longevity of your pipe’s fixed downstem.

How do I measure my pipe’s downstem?

What size downstem do I need for my pipe, you might ask? Downstems are sold with two dimensions in mind: the length of the downstem, and the size of the joint in which the downstem will fit.

To find out the best length of your downstem (aside from buying multiple downstems of different sizes and trying them out), you can use a pencil or pen. Stick the pencil inside your bong through the joint until the tip (where all the diffusion holes would be) are completely submerged in water. The downstem is likely around one inch above the bottom of the bong. At this point, mark where the pencil leaves the joint. Take the pencil out, and measure how many inches from the mark to the pencil tip, in half inch increments--that’s how long of a downstem your bong needs!

Additionally, you’ll need to know the joint diameter of your bong, of which there are three main sizes for bong joints: 10mm, 14mm and 18mm. 10mm are uncommon and are usually for mini rigs. The joint sizes refer to the width or diameter of the joint, so these are pretty easy to measure compared to a downstem’s length--just grab a ruler and see how many millimeters across the joint is. Once you have this info, you’re ready to get the right downstem for your bong.

If you’re considering buying a new bong and are looking into downstem choices, do consider that while mini rigs are more portable and take up less space, 10mm joints don’t have as many accessories available as do the more common 14mm and 18mm. Also, the smaller the joint, the faster the downstem will clog. 18mm joints mean a slightly wider downstem that won’t fill up with resin as quickly as a smaller jointed downstem.

What are the different styles of downstems?

Now for the fun part--while a large part of downstems is just making sure you have the right size and are extra careful when handling them, since tiny delicate pieces of glass do tend to break, you can have a lot of fun when buying a downstem. There’s a variety of downstem styles out there, and they can be just as unique and impactful as buying a new percolator for your bong.

  • Tree perc downstem: Named for the so called multiple tree branches emanating from the top of this downstem, this tree perc downstem is more like having seven sources of diffusion instead of one. If you’re looking to get softer smoke that has better flavor, consider a tree perc downstem.
  • Fire cut downstem: When it comes to something as detailed as a downstem, it’s the little things that give you the best results. This fire cut downstem might look like all other downstems, but closer inspection reveals a series of holes instead of slits in the downstem. These holes, cut with a hydrogen torch, provide superior diffusion compared to ordinary slitted downstems.
  • Metal downstem: If you have a nice collection of bongs, then you know the struggle of buying multiple accessories of different sizes and genders to use on your water pipes. For those really looking to upgrade, this adjustable titanium downstem will simplify your world with its high-tech features. You can use this metal downstem in any size joint, and it extends based on the dimensions of your bong. Not only is this diffusion on this metal downstem fantastic, it’s also much easier to clean and far less likely to break than other glass downstems.

Do you have a favorite style of downstem that wasn’t discussed here? What did you learn about downstems that surprised you?


Julia, a flower child hailing from Spain, discovered her love of fresh herbs years ago when she accidentally became head of product at a farm in Oregon.

She loves long walks on the beach, accordion music and of course spending time with her favorite Yocan Evolve D (only in blue though). She promises to not bias her blog posts towards vaporizers too much, but no guarantees.




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