The Daily High Club Guide to Bong Downstems: Sizing, Types, Cleaning

December 5, 2025 By Daily High Club

A broken downstem can bring a session to a halt, but finding the right replacement doesn't have to be a challenge. Whether through an accident during cleaning or regular wear and tear, a broken downstem is a common issue for bong owners. If the downstem is the only part of the bong that's broken, a new one is really all you need.

Without a functioning downstem, your water pipe cannot create the necessary seal for a proper hit. Or maybe you just scored a dope new bowl online, only to get it home and realize it doesn't fit. Knowing your bowl size is crucial for replacements and compatibility, and this guide breaks down an easy way to check.

Understanding the essentials of joint sizes, such as the common 14mm or 18mm options, is crucial for replacements and compatibility. This guide will provide the clarity you need to select the correct part.

Daily High Club has an extensive selection of downstems with various materials and sizes to fit any piece. Ensuring you choose the correct type and size for your bong is essential for proper function. By the time you finish this guide, you’ll be a downstem sizing pro and will never order the wrong part again.

What is a Bong Downstem, Anyway?

A bong downstem is the unsung hero of the entire smoking experience. Think of it as the vital bridge that connects the bowl, where you pack your herb, down into the water. The downstem's entire purpose is to be the pathway that makes filtration happen; it is the first major component in the filtration system.

This crucial piece connects the bowl to the main chamber, helping to create the suction that pulls smoke or vapor into the water before you take your hit.

Does a Bong Even Need a Downstem?

So, can you just skip it? For 99% of bongs, the answer is a hard no—a downstem is non-negotiable. While some bongs have fixed downstems, most require a removable one to function, making it an essential part a bong needs to do its job. It's not just a random glass tube; it has two critical jobs:

It Creates the Airtight Seal: This seal is what lets you build up suction. Without it, you're just pulling air and getting zero smoke. Without the seal created by your downstem, your hit might leave you feeling like something's missing, but with it, you'll experience the full potential of your smoking device.
It Enables Filtration: This is the big one. The downstem forces the hot, harsh smoke from the bowl to go under the water. This process directs smoke into the water where it undergoes physical changes that cool and filter it. This process, known as percolation, breaks the smoke into bubbles, which cools it down and filters out ash. That’s what makes a bong hit feel smoother.

Fixed vs. Removable Downstems

You'll run into two main types :

Fixed Downstems: These are permanently fused or welded to the bong, sometimes as a built-in three-slit downstem that maximizes airflow. They're often on fancy, complex pieces. The downside? If one breaks, the whole bong is basically toast. They can also be a nightmare to clean.
Removable Downstems: This is the standard. It's the separate glass piece you can pull out. They're super common because they are customizable and, most importantly, easy to clean and replaceable. If you break it (and let's be real, it happens), you just buy a new one. This guide is all about these removable ones.

How to Find Your Bong Downstem Size (The Easy Way)

Getting the right downstem size is the most important part of making your bong work. Choosing the right diameter is essential to create a secure, airtight seal. If the fit is wrong, you won't get a good seal, and your hits will have poor airflow or be impossible. The good news is you only need to worry about two measurements: Joint Size (the diameter) and Length.

Step 1: Find Your Joint Size (10mm, 14mm, or 18mm?)

Joint size is the diameter of the opening on your bong. There are three industry-standard sizes: 10mm, 14mm, and 18mm. 10mm is tiny and mostly for small dab rigs, while 18mm is for big bongs that need max airflow. 14mm is by far the most common size.

To measure your bong bowl joint size, you'll need a ruler or a measuring tape that shows measurements in millimeters (mm). Carefully detach the bowl piece from your bong to get a clear view of the joint. Using your ruler, measure the inside diameter of this joint at the widest part of the circle. A caliper, especially a digital one, will provide the most accurate measurement if you have one.

Step 2: Find the Correct Length

Length is just as critical. A downstem that's too short won't reach the water, so you get zero filtration—just hot, dry smoke. A downstem that's too long will hit the bottom of the bong, which stops it from sealing properly. The stem should be long enough to reach the water chamber without touching the bottom.

If your original downstem is broken or lost, you can easily find the ideal length.

To take the measurement, we recommend inserting a pencil into the joint.
Push it as far down as you would like your downstem to fit, leaving about a half-inch of space from the bottom. This clearance is essential.
Then, hold your pencil against the place where the joint meets the inside of your water pipe.
Mark and measure the length on your pencil, and you have your ideal length. Official downstem length is measured from where the ground joint meets the stem to the tip of the stem.

What's a "Reducer" Downstem? (e.g., 18mm to 14mm)

You'll often see downstems listed with two numbers, like "18/14" or "18mm to 14mm". This is super common and just means it "reduces" the joint size. The first number (18mm) is the male joint that fits into your bong.

The second number (14mm) is the female joint on the downstem that holds your bowl. This setup is designed to seamlessly connect a 14mm slide/bowl into an 18mm stemless opening, giving you way more options.

Does the Type of Downstem Make a Difference?

Absolutely. How your downstem works is dependent on the design of the tip. That simple tube is a crucial piece controlling the quality of your hit and the entire smoking experience.

The Science of Percolation: From Bubbles to Bliss

The downstem is considered a basic type of percolator. The process is all about creating small bubbles, which allows more surface area coverage for more cooling effects. More bubbles equal more surface area.

When more of the smoke's surface area touches the water, you get way better cooling and filtration. This is the secret to a smoother, cleaner, less-harsh-feeling hit. While a basic downstem works, there are many upgrades. Here are the most common types of downstems :

Slitted (Diffused) Downstem: This is the most common upgrade. It has small, vertical cuts at the base that chop up the smoke into a cascade of fine bubbles. These diffused downstems add smoothness with additional filtration.
Tree Perc Downstem: Features multiple "arms" or rods that descend into the water, each with its own slits for maximum diffusion.
Honeycomb Downstem: Contains one or more discs perforated with a pattern of holes resembling a honeycomb, creating a dense field of small bubbles.
Fire Cut Downstem: A specific style of slitted downstem known for its clean and effective percolation.
Showerhead Downstem: Shaped like a showerhead, this type has multiple holes or slits at its flared bottom, evenly distributing smoke into the water.

Material Matters: Glass, Silicone, or Metal?

The material you choose mostly comes down to your lifestyle and preferences.

Borosilicate Glass: This is the standard for a reason. It gives you the purest, cleanest flavor with zero weird taste. It's built to last and engineered for epic sessions. The obvious downside? It's glass, and glass can be fragile and may need frequent replacement.
Silicone: If you’re clumsy or always smoking on the go, silicone is your best friend. It's virtually unbreakable and perfect for travel. The only trade-off is it can be difficult to clean and can sometimes hold onto odors if you don't clean it regularly.
Metal (Aluminum): This is the indestructible, buy-it-for-life option, favored for their longevity and sturdiness. The best part is that many metal stems (like the "Invincipole") are adjustable, which completely solves the problem of measuring for the perfect length.
Ceramic: Offering a unique aesthetic, ceramic downstems can retain heat well, keeping smoke warm and flavorful. However, like glass, they can be fragile and may need frequent replacement.

How to Clean Your Downstem (and Get it Un-Stuck)

There’s no worse feeling than finding your downstem stuck in your bong, "glued" in place by sticky resin. Whatever you do, stop. The number one rule is: Do NOT use brute force. Yanking on it is the fastest way to break your glass and ruin your day. Instead, be patient and try these safe methods:

The Hot/Cold Water Method: Run hot (not boiling) tap water over the outside of the bong's joint for a minute. A quick soak in hot water can help loosen stubborn parts. Gently try to twist the downstem. If it’s still stuck, a light twist or wiggle should free it up.
The Solvent Soak: Grab some 91%+ Isopropyl Alcohol (ISO) and carefully drip it around the stuck joint. The alcohol will work its way into the gap and start to dissolve the resin holding it hostage.

The Gold Standard Cleaning Method

Once your downstem is free, the best way to get it sparkling is the classic combination of Isopropyl Alcohol and salt. This is the DHC Gold Standard for getting your glass sparkling.

Place your downstem inside a sealable plastic bag (like a Ziploc).
Pour in enough 91% or higher Isopropyl Alcohol to completely cover the piece.
Add a generous tablespoon of coarse salt (Epsom salt or sea salt works great).
Seal the bag and shake it vigorously for a few minutes. The ISO is the solvent that dissolves all the resin, while the salt acts as a tough abrasive to scrub the inside clean.
Once it looks new, rinse the downstem thoroughly with warm water until you can no longer smell any alcohol.
Let it air dry completely, and you're good to go.

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