The water in a bong should cover the bottom slits of the downstem by about 0.5 to 1 inch. For percolators, each perc must be fully submerged. Too much water causes splashback and drag; too little gives harsh hits with no filtration.
How to Nail Your Waterline Every Time
If the water in your bong isn’t set right, you’re either wasting good flower or giving your throat a rough time. Smoke needs just enough water to cool down and clean up.
Too much and you’re sipping from the mouthpiece. Too little and you’re coughing through fire.
The sweet spot is about half an inch above the slits in your downstem.
There are signs when the waterline is wrong.
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No bubbling or overly loud bubbling
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Water hitting your lips
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Hot or scratchy hits
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Airflow feels restricted or heavy
If you're looking to lock in the basics, the 16" Straight Tube 50x7MM from the Thick Ass Glass collection is the most user-friendly piece I can recommend. It gives you a clean draw, solid weight, and thick enough walls to shrug off accidents.
In the sections ahead, I’ll break down what water actually does inside a bong, how to fill for different designs, what happens if you skip the water change, and whether stuff like temperature or altitude changes how your bong performs.
Why Water’s in There: More Than Just Bubble Trouble
The moment you light up, your bong becomes a filtration system. The glass holds the shape, but the water handles the function.
Without water, smoke moves straight from combustion to your lungs, carrying heat, ash, and everything else along with it. That kind of hit feels more like punishment than pleasure.
What Happens When Smoke Meets Water
When smoke is pulled through the downstem and hits the water, the bubbling creates turbulence that filters and cools.
Heavier particles like ash and tar get trapped in the water while the smoke breaks into smaller bubbles. This increases surface contact and helps lower the temperature fast.
That movement you hear and feel is the smoke being processed. If the water level is correct, the bubbles rise cleanly and evenly. In turn, this ensures efficient filtration that translates into a smooth hit.
Benefits of Proper Water Filtration
When your waterline is dialed in, everything about the session improves. The difference shows up in comfort, taste, and the ability to take a proper pull. These are the real benefits:
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Reduces throat and lung irritation
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Filters out resin, ash, and other harsh particles
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Allows for deeper hits without triggering coughs
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Preserves more flavor by cooling smoke before it reaches your mouth
Water is not an accessory. It is what separates a good hit from a wasted one.
Can You Hit a Bong Dry and Still Get High?
A bong without water still works in the technical sense, but that’s where the upside ends.
You can inhale and get high, but the experience falls apart fast. Smoke moves through uncooled and unfiltered, which means you’re pulling hot air full of ash, resin, and tar.
Even premium flower tastes flat and harsh. The hit is dry, scratchy, and unforgiving.
What You’re Risking Without Water
Filtration is the reason bongs exist. Removing it defeats the entire design.
You lose cooling, you lose smoothness, and you put stress on your lungs and your piece. Glass without water is exposed to sudden heat that can lead to microfractures, especially in thicker borosilicate.
The thicker the glass, the more it benefits from the insulating effect of water.
If you ever forget to fill your piece or run out of clean water, even a small splash can change the outcome. It won’t deliver the full filtration effect, but it will cool the smoke enough to make the hit tolerable.
Still, a dry rip should be the exception, never the routine. Bongs are engineered for water. Skip that part, and you're just using expensive glass the wrong way.
How to Fill a Bong Like You’ve Been Doing It for Years
There’s no trick to filling a bong correctly, but there is a method. The goal is to hit that sweet spot where the smoke filters and cools without flooding the chamber or choking airflow. It’s worth putting some effort into getting it right, as your smoking experience will be totally different.
Follow these steps and you’ll have it dialed.
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Remove the bowl and tilt the bong slightly to one side. This gives you a better view of the downstem and prevents splashback while pouring.
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Pour water slowly through the mouthpiece. If your piece makes it easier, you can also fill it by removing the downstem and pouring directly into the chamber.
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Watch the slits on the downstem and stop once they are covered by around half an inch of water. This is the optimal point for airflow and filtration without drag.
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Do a test pull without lighting anything. If water splashes up into the mouthpiece, you’ve overfilled. Empty a small amount and test again.
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Add or reduce the water until the bubbling feels smooth and the pull is easy. It should sound active without gurgling or sputtering.
A helpful habit is to tilt the bong the same way you use it during sessions when checking the waterline. The angle can shift the water level slightly, especially in straight tubes or taller beakers.
Getting it right once makes it easier to repeat every time.
Different Bongs, Different Fill Strategies
Bong shape changes how water behaves inside the piece.
Straight tubes, beakers, and percolator setups all need different water levels to work properly. A one-size approach makes the piece harder to clear, dulls filtration, or floods the mouthpiece.
Each design calls for a specific fill pattern to function the way it was built to.
Straight Tubes
Straight tubes are simple and responsive. Water should sit just above the slits or holes in the downstem. This gives you minimal drag with quick, clean clears.
Since there are no extra chambers or features to compensate for, adjustments are easy. You can test your water level in seconds and dial in exactly where you want it.
Top Pick: 18" Straight Tube 50x9MM
This tube keeps airflow sharp and focused, with thick glass that feels stable in the hand. It is a no-nonsense daily driver for anyone who values precision in their pulls.
Beaker Bongs
Beakers hold more water due to their wide base, but the same downstem rule applies.
Cover the slits by about half an inch and stop there. More water increases diffusion and adds a little weight to the bottom, which helps keep it steady on the table.
The larger chamber creates a smoother pull with a bit more volume.
Top Pick: 16" Beaker Bong Bamboo 50X7mm
With a reinforced bottom and natural aesthetic, this piece balances style and performance. It feels durable and smooth, with airflow that opens up as the beaker fills.
Perc Bongs
These bongs are built to ensure maximum filtration. While there are many different styles of percolators, the same rule applies. They need to be properly submerged to work as intended.
Too little water and the percs do nothing. Too much and the airflow becomes restricted. However, if you can manage the right level the result is some of the smoothest hits you can pull from glass.
Top Pick: 14" Streamline Fixed 8-Arm Tree Beaker
This model stacks clean bubbles from every arm with almost no splash. The fixed design simplifies the setup, and the tree perc adds real function you can feel on the inhale.
Old Bong Water Is Not Your Friend
Used bong water is a problem waiting to happen. It might look harmless sitting at the bottom of the chamber, but the moment you light up and pull through it again, the issues show up.
The smoke gets musty. The flavor turns sour. And if the water has been sitting long enough, the hit feels like it came through a swamp.
Clean water helps deliver the full benefit of your glass. Dirty water cancels all of that out.
How Often to Change?
The cleanest approach is to change the water after every session.
Even one round of use loads the water with ash, resin, and tar. Leave that mix overnight and you’ve already got the start of something you do not want to inhale. If you’re smoking multiple times in a day, it’s worth dumping and refilling every time. Once a day is the absolute minimum.
Fresh water means each hit goes through a clean filter.
That preserves flavor, prevents build-up, and makes cleaning easier over time. Dirty water sits in your piece, coats the walls, and turns every hit into a worse version of the last.
What Happens If You Don’t?
The longer water sits, the more it breaks down.
It starts to smell. It carries mold and bacteria. It thickens slightly with resin.
At a certain point, no type of high-end glass can overcome what’s going on inside that chamber.
And yes, someone once asked if bong water is safe to drink. It is not.
That is not a myth, a joke, or a dare. It’s just stupid and dangerous.
What To Do With Old Water
When you’re done, dump the water into a sink or toilet. Avoid pouring it into a container you use for anything else.
Give the piece a quick rinse, even if you don’t plan to smoke again right away.
Letting the resin sit makes it harder to clean and locks in the smell. Starting fresh only takes a few seconds and makes every session better.
Practice Makes Perfect Waterlines
Getting the water level right takes a little practice, but once you’ve done it a few times, it sticks.
You’ll know by the way it pulls. Covered slits, clean airflow, no splash, no drag. That’s when your piece works the way it’s supposed to.
Whether you’re filling a tall straight tube or a stacked tree perc, it helps to have glass that’s built with real function in mind. Thick Ass Glass makes pieces that are easy to work with and hold up over time.
If you’re ready to upgrade or want a setup that makes every hit feel special, you’ll find it here.
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