Bucket

Buckets are tools used to carry water, lava, or milk. Water and lava can be obtained only by using the bucket on a source block; shallow, running fluids cannot be collected. Milk buckets are collected by right-clicking with an empty bucket on a Cow or Mooshroom.

While underwater, simultaneously moving forward and filling an empty bucket will create a temporary air pocket, which can be used to refill the player's air meter. By repeating this technique, it is possible to stay underwater for extended lengths of time.

Buckets can be crafted from iron or recovered from dungeons. There is a 53% chance (approximately) of finding one bucket in a dungeon chest.

Usage
Empty buckets can be used to capture water or lava springs, extracting the source block for later use; source blocks can also be taken from lakes of water or lava. Buckets can be used to create air pockets underwater, refilling the player's air meter.

Water buckets can be used to extinguish fires and to drain or fill lakes. They can also be used to clear and harvest small fields of tall grass, as well as wheat, potatoes, pumpkin stems, melon stems or carrots (The water can be collected afterward.) Buckets can also be used simply to create pools of water: a single-block pool can hydrate a 9&times;9 plot of farmland; two buckets arranged diagonally in a 2&times;2 pool form an "infinite water source," from which water can be drawn indefinitely. Finally, a water bucket can be used to fill cauldrons (which allow players to fill potion bottles in the Nether).

Lava buckets have three main uses: creating weapons or barriers to handle mobs, producing obsidian or cobblestone, and fueling furnaces (This technique provides the longest lasting fuel in the game.) Buckets used in smelting can be retrieved as soon as the process begins.

Milk buckets can be drunk to remove poison, food poisoning, withering, et al, or crafted with eggs, wheat, and sugar to produce Cake. Unlike water and lava, milk cannot be placed in the environment.

Types of buckets

 * Water bucket - holds one water source block
 * Lava bucket - holds one lava source block
 * Milk bucket - used to make cake. Milk can be used to cure poison and immediately stop potion effects.

However, in the Pocket Edition, buckets can hold any block, with the data value corresponding with what will be placed. Since the Bucket of Air doesn't place anything, this slot is used for the milk bucket. Keep in mind all of the special buckets can only be obtained with an external editor. They have the normal bucket sprite.

Trivia

 * While underwater, holding an empty bucket and right-clicking will create a temporary pocket of air around the player's head which lasts long enough to replenish the air meter. If a block is within reach, a bucket can be emptied by right-clicking on it. By repeating this process, it is possible to stay underwater for extended lengths of time.
 * Each bucket seems to be able to hold just over 264 gallons (1 m³) of liquid.