Glass Bottle

A glass bottle is an item that can hold water, potions, dragon's breath, or honey.

Obtaining
Glass bottles can be obtained by crafting, drinking potions, fishing, or from witch drops.

Potions
Drinking a potion returns the empty glass bottle. Throwing a splash potion or a lingering potion does not return a glass bottle, but brewing a lingering potion gives back a glass bottle.

Witches
Witches have a chance of dropping 0–6 glass bottles upon death. This is increased by 3 per level of Looting, for a maximum of 0-15 glass bottles.

Cauldrons
Using a water bottle, (or, $$, a potion, splash potion, or lingering potion) on a cauldron that is not yet full adds that liquid to the cauldron, leaving the player with an empty glass bottle.

Usage
Glass bottles can be filled to make water bottles, which can then be used to brew items with a brewing stand. Glass bottles are also used to hold the resulting potion.

Water
A bottle may be filled with water by holding it in your hand and it on a water source block or a cauldron that has water in it. It can also be filled using a waterlogged block. [ JE only]

MCPE-83420

Also, a bottle may be filled by powering a dispenser containing a bottle and pointed at a water source block. This does not work with cauldrons.

If filled via a water source, the water is unaffected. If filled via a cauldron, $1/3$ of the water in the cauldron is removed. Therefore, using a cauldron to fill water bottles is inefficient, except in the Nether where it is normally the only way to fill bottles.

Potion
$$, a bottle may be filled with potion by it on a cauldron containing potion. When the bottle is filled, $1/3$ of the cauldron's potion is removed.

Dragon's Breath
a glass bottle in clouds emitted when the ender dragon breathes or shoots a dragon fireball fills the bottle with dragon's breath.

Honey
If a bee nest or beehive is full, the player can a glass bottle on the block, or may power a dispenser that contains a bottle and is pointed at the block, which empties the block and creates a honey bottle.

Trading
Expert-level cleric villagers have a 50% chance to buy 9 glass bottles for one emerald as part of their trade.

Expert-level cleric villagers have a $2/3$ chance to buy 9 glass bottles for one emerald.

ID