How do you clean a bong?

Short answer

Empty the water, pull out the bowl and downstem, then pour in 91% or stronger isopropyl alcohol with a tablespoon or two of coarse salt, plug the openings and shake for 1 to 2 minutes. Rinse with warm (not hot) water until the smell is gone, and soak the small parts in a zip bag of the same mix. A weekly clean like this takes about 15 minutes.

The 15-minute method

This is the standard shop method for borosilicate glass bongs. You need 91% or 99% isopropyl alcohol, coarse salt (kosher or rock salt), a zip-top bag, plugs (silicone caps, or your thumbs and a paper towel), and a pipe brush or swabs.

Empty and rinse. Dump the old water and give the bong a quick rinse with warm tap water to loosen surface residue.
Remove the parts. Pull the bowl and the downstem (if it is removable). Put them in a zip bag with enough alcohol to cover them and a teaspoon of salt. Let them soak while you work on the main piece.
Add alcohol and salt. Pour in roughly 1/4 to 1/2 cup of alcohol (enough to slosh across every surface) and 1 to 2 tablespoons of coarse salt. The salt is the scrubber; the alcohol dissolves the resin.
Plug and shake. Cover the mouthpiece and the joint and shake hard for 1 to 2 minutes, swirling so the salt reaches the base and any percolator. For heavy buildup, let it sit 15 to 30 minutes and shake again.
Rinse. Rinse with warm water until there is no alcohol smell. Run a brush or swab through the neck and joint.
Finish the small parts. Shake the zip bag, scrub the bowl hole with a swab, and rinse.
Dry. Let everything air-dry fully before refilling.

How often to clean

Task	How often	Time
Change the water	Every session or every day	1 minute
Quick rinse and swab of the bowl	Every few days	3 minutes
Full alcohol-and-salt clean	Weekly with regular use	15 minutes
Long soak for neglected glass	As needed	1 to 12 hours

See how often you should change bong water for the daily side of this routine. If you would rather skip alcohol, there is a separate method in how to clean a bong without alcohol.

Bongs with percolators and ash catchers

Percolators trap residue in small slits that salt cannot always reach. Fill the chamber with alcohol, plug, and let it soak 30 minutes before shaking. A ready-made cleaner with a fine abrasive can help on tight showerheads and honeycombs. Ash catchers get the same treatment as the downstem: soak them in a bag. More on these parts in what is a percolator and what is an ash catcher.

Common mistakes

Using 70% alcohol. It has more water and cuts resin much more slowly. Use 91% or higher.
Rinsing with boiling or very hot water. A sudden temperature change can crack glass, especially at the joint. Warm tap water is enough.
Waiting months between cleans. Baked-on residue can take an overnight soak. Weekly cleans take minutes.
Putting alcohol on silicone or acrylic. Silicone bongs can go in the dishwasher (check the maker's instructions); acrylic can cloud with alcohol, so use warm soapy water.