What is a Downstem?

With so many accessories on the water-pipe market, the concept of having a downstem might seem like an unknown territory to some. A quality smoking device usually includes a detachable component that connects the bowl to the main chamber. Usually, this tube will be made out of various materials like silicone, glass, etc.. In this article, we will be looking at what a downstem actually is, as one of the most fundamental components crucial to all water-smoking devices.

Purpose of a Downstem

The Purpose of a Downstem

The main function of the tube that connects your bowl to the water chamber is to create an airtight suction as you inhale through the mouthpiece. This will ensure that your hit filters thoroughly through the water. Some downstems are slightly perforated at the end which breaks up the smoke. This is known as a diffused downstem, and creates a cooling effect that makes the smoke easier to inhale. A quality made fixed piece will never have the downstem directly touching the bottom of the water chamber. Whether you have a traditional water-pipe, dab rig or bubbler, the purpose of the downstem remains the same.

Types of Downstems

Types of Downstems

Some downstems are directly attached to the entire smoking apparatus, thus making cleaning a bit more meticulous. The option of a detachable downstem adds to the luxury of being able to swap out for a personal customization. This feature can be extended to pieces made of wood, metal, glass, silicone, ceramic, etc.. Some downstems offer a basic percolated mechanism which further enhances the experience by allowing airflow to distribute the smoke more efficiently. This combines with a diffused design to offer more surface area for the smoke to filter throughout the water. The main difference between a downstem and a traditional percolator is that the downstem is usually removable as a basic tube.

Downstem Sizes

You will find the three main sizes as being either 10mm, 14mm, or 18mm (aka 19mm), with any one downstem ranging from 2 – 7 inches in length. Making sure you get the correct size to ensure an airtight seal before you make a purchase is paramount. Furthermore, the bowl piece that slides into the downstem will have to fit snugly as well. It is important to remember that the downstem is the longer straight end of the entire piece, including the male joint (the cloudy bowl-shaped opening on one end) which is used to measure the length. These joints can be either male (tapered slightly narrowed) or female (tapered wide with a lip). These can even come combined to form an adapter. The diameter determines the overall function of your smoking apparatus:

10mm Downstem Joint

The smallest of the three main sizes, this can be easily measured using a dime and pencil. If the dime does not fall into the joint opening, then it is either a 10mm or a 14mm. The 10mm joint will not accept the width of a standard pencil, whereas the 14mm will.

14mm Downstem Joint

Like the 10mm, a dime will not fall through the joint opening of a 14mm. However, a pencil will fit snugly into the 14mm opening. It is important to note that some diameters for a water-pipe call for a wider opening on the exterior joint, whereas the bowl joint may be smaller, such as an 18mm/14mm.

18mm Downstem Joint

The actual size for an 18mm is 18.8mm. Rounded off, it is also commonly called a 19mm. Either way, mentioning the 18 or 19 will still give you the same product. A dime will fall straight into the joint opening for this diameter.

When choosing the correct size for your piece, determining the length is a matter of fitting either a pencil or a straw through the main water chamber. Go as far back as you can and then pull away about half an inch from the end. With your thumb or a pen, mark the pencil at the opening of the joint where the pencil begins to stick out. This is the length of your downstem. Measure this to determine the proper length.

Glass Downstem vs Silicone Downstem

Glass Downstem vs Silicone Downstem

While glass is rather delicate by comparison, both can be cleaned and utilized in almost the same manner. However, most food-grade silicone pieces are dishwasher-safe, whereas a glass piece is not. When accidents happen, a glass downstem will almost always have to be replaced, whereas a silicone piece is almost totally indestructible. Silicone downstems are heat-resistant and usually diffused as well. They are just as easy to clean and can come in a variety of colors, so it really just boils down to a matter of preference.

Diffused vs Honeycomb Downstem

Diffused vs Honeycomb

In terms of design, a diffused downstem will offer a basic form of percolation. Small slits on the sides towards the end of the tube allows the smoke to break down into smaller bubbles which creates a smoother hit. A honeycomb design uses the center instead of the sides which further breaks down the smoke using small holes. The difference to remember is the more holes it has, the smoother your hit will be.

Bong Downstems

A traditional water-pipe differs from a percolator in that the smoke is usually filtered through just one chamber. The downstem on a basic bong utilizes the same methods of measurement when determining which one you need. The tubes are almost always detachable and is one of the more popular smoking devices on the market. While the bong itself is not usually as elaborate as a percolator, the downstem can be diffused to include the same mechanism of water filtration. The tube that usually comes with a bong is a straight-end hole with no perforation. This makes the smoke more harsh and less cool, thus necessitating the need for a diffused downstem.

Downstem Add-ons

Downstem Add-Ons

There are many add-ons that enhance the experience of using a water-smoking device. Depending on the design, most of these can be placed directly into the downstem:

Ash Catcher

A special water-chamber that attaches to the main apparatus and can hold the bowl, smoke & ash are filtered through the water in this chamber. The ash catcher usually has a 45 degree angled male adapter that fits into the main water chamber. The top contains the opening where the downstem connects into, creating an additional layer of filtration.

Bong Bowl

The bowl can be either male or female depending on the design of your device. Some come with handles to remove the bowl from the downstem in order to safely pick up and clear the smoking device. The bowl is placed directly on the downstem to house and safely burn your material. There are many different types of bowls depending on what material you are using. The standard bowl for dry herb vaporizersis usually round, while a dab nail can be best described as a cylinder for example. More on that in a bit.

Oil Reclaimer

Made specifically for dabbers, otherwise known as oil rigs, an oil reclaimer is a small chamber that collects unused oil as it drips down into the collection chamber from heat. This oil can be reused and ensures that nothing goes to waste. This little compartment is sometimes clamped in place on the bottom and can be easily removed. Other designs feature the oil reclaimer as a permanent chamber in a male/female adapter.

Dab Nails

A specialized bowl meant for concentrates, this accessory uses a torch instead of a standard lighter to vaporize your material. The dab nail is inserted into the main water chamber as the downstem would be, and is used with most percolators as a standalone method for consumption.


A separate unit with a coil that wraps around the nail, this device is purely electronic. It works by heating up the coil to the set temperature which essentially vaporizes your concentrate in the nail. Tools like these are meant to enhance the flavor profile while customizing your heating preferences.

How to Clean Your Downstem

If you do not own a silicone downstem that can be placed in the dishwasher, then this simple step-by-step process is what you need:

Start by removing the downstem from your smoking-device. Wipe away any excess buildup with a paper towel. If your tube is really dirty or stuck, consider soaking in a plastic bag with rubbing alcohol for a couple of hours to soften up the residue. With one finger covering one end of the tube, pour in some salt. Next, pour in some rubbing alcohol and cover both ends with paper towels or your fingers. I recommend gloves for this step. Shake back and forth and repeat this process until the majority of your residue has been cleared out. With an alcohol-soaked q-tip, wipe away any leftover residue and rinse thoroughly with water. Maintain the cleanliness of your device as often as needed to ensure the integrity of your smoking experience. Put back together and enjoy!

Where Can I Buy a Downstem?

Choosing a quality downstem is just as important as knowing where to buy one. Remember when picking a downstem to ensure that it fits your device exactly! Failure to pick the correct size can result in having to replace your downstem or the entire device due to breakage. As long as you get the right fit, the rest is just a matter of preference. Whether you are looking for a bong, bubbler, oil rig, or vaporizer, just make sure that you go to a reputable head shop that has all the accessories and replacements you need.

Another great place to look is online. Make sure you visit vapevetstore.com and take a look around. They have everything you need and offer free shipping within the US!

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Silicone Downstem



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