Gravity bongs are an easy-to-make alternative to smoking bowls, bongs, or joints that can be built with items you probably already have in your home. In this guide we’ll show you how to make a gravity bong and offer some helpful tips along the way.

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What is a Gravity Bong?

A typical gravity bong consists of a water-filled base, a small bottle that acts as a vacuum, and a bowl head. When used, the grav bong creates suction that pulls the cannabis smoke from the bowl head into the chamber of the small bottle. Once the smoke fills the chamber, the bowl head is removed and the user inhales from the mouthpiece while plunging the bottle back into the water.

Does a gravity bong produce a better hit?

Gravity bongs tend to produce a more concentrated hit than a traditional bowl or bong. When created and used properly, grav bongs can pull an entire bowl’s worth of smoke into the chamber at once. The lack of additional air in the chamber means that grav bongs hit — hard.

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A single hit from a grav bong can be extremely strong, and they are best used by more experienced smokers  It’s important to remember that most homemade grav bongs are made from plastic. Many would agree that smoking from plastic equipment doesn’t make for the most pleasant smoking experience.

Those who enjoy the subtle flavors and aromas of cannabis may prefer to smoke out of glass for a more true flavor. If this sounds like you, consider checking out the Gravitron from GRAV. This glass gravity bong system offers the powerful hit you want from a geeb with a truer flavor profile.

How to make a gravity bong

The grav bong has been tweaked and altered throughout the years, but the basic concepts remain the same: differences in pressure are used to pull highly concentrated smoke from the bowl head into the chamber.  We’ll show you how to make a gravity bong the easy way.

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Our classic “bucket bong” technique involves fitting a smaller plastic bottle inside a 2-liter soda bottle or other larger plastic container that serves as the base. The only tools required are a knife and scissors. If you want to make a glass gravity bong, you’ll need a special glass cutting tool or Dremel. 

What you’ll need:

  • 16.9 - 20 oz. (approximately 500-600 mL) plastic bottle with cap*
  • 2-liter soda bottle, a bucket, or large plastic container*
  • Utility Knife or Xacto Knife
  • Scissors
  • Bowl head: You can buy glass or stainless steel gravity bong bowl heads or create a makeshift bowl head using materials around the house.

*Note: A 16.9 oz bottle with a 2-liter soda bottle base creates a compact gravity bong that’s easy to maintain and transport. For a larger gravity bong, consider using a 2-liter bottle as the smaller bottle and using a 2-gallon (or larger) bucket as the base. There are many possible combinations of small and large containers that will work effectively, so feel free to get creative!

Step 1: Cut the Smaller Bottle

Use your knife to carefully remove the bottom of your smaller container. Make one straight cut all the way around the sidewall of the bottle. To make sure you have an adequately-sized chamber, try not to cut off more than a quarter of the bottle’s height. {Hint: If you don’t want to throw it away, you can use the bottom of this bottle to germinate seeds for your herb garden!}

Step 2: Cut the Large Container

If you’re using a bucket or other container with a wide opening, you can skip this step. If you’re using a 2-liter soda bottle for your base container, you’ll want to cut off the narrow top of the bottle so that the smaller container can fit easily inside the opening. Use your knife to make one even cut around the side wall of the container about halfway up from the bottom. You can discard the top of the bottle or save it for future use as a funnel. 

Step 3: Add Bowl Head

If you have a pre-made bowl head for grav bongs, you can insert it into the top of your bottle and get to smoking. If you’re making your own gravity bong bowl head, take the cap from your smaller bottle and use your scissors or knife to carefully poke a small hole in the top of the cap.  There are two common ways to make your own bowl head: 

Option 1: Some users will fashion a bowl head out of aluminum foil by wrapping the foil around the small bottle cap and forming a bowl shape by pinching and molding it, then poking a hole from the hole in the top center of the bottle cap through the foil to ensure proper air flow.

Option 2: You can also glue or tape a second bottle cap back-to-back with the first and use scissors or a knife to poke a hole straight through the center of both to create a plastic bowl. Plastic is not typically the preferred material to use for the combustion of dry flower due to the presence of potentially harmful chemicals. Use this method with caution and consider adding a pipe screen and lighting your gravity bong with a hemp wick.

Alternatively, you can fit your bottle cap with any glass bowl head you may have left over from an old bong. Carefully cut out the top of the small bottle’s cap to snugly fit the circumference of the glass piece and gently slide them together. 

How to Use a Gravity Bong

Once you know how to make a gravity bong, you’ll want to know how to smoke a gravity bong as well! The technique is simple:

  • Fill your base bucket almost to the top with water. 
  • Place your smaller bottle into the base. 
  • Loosely screw or place your bowl head onto the small bottle. 
  • Coarsely break up or grind your weed and place it into the bowl head. 
  • Use a lighter or hemp wick to ignite your cannabis while slowly lifting the smaller bottle upward until just before the bottom edge of the small bottle reaches the surface of the water. 
  • When the chamber is filled, remove the bowl head cap and place your mouth to the mouth of the small bottle. 
  • Inhale as you allow the small bottle to sink back into the bucket.

Remember that gravity bongs produce a highly concentrated hit. Go slow and know your limits when using cannabis products.