Water

"You might not consider water a "block" as such, because you can't pick it up and put it in your inventory without the help of a distinctly circular bucket, but we make the rules and we say it's a block. So there."

- Duncan Geere

Water is a natural fluid.

Obtaining
Water does not exist as an item, but can be collected by using a bucket on a full cauldron or water source block.

Natural generation
Water naturally generates in the Overworld to make oceans, lakes, rivers and springs. It also generates in village and desert wells, strongholds and woodland mansions.

Swimming
The button for is the same as the button for jumping; players and mobs will sink slowly in water, unless swimming. Holding the swim button will raise the player through the water, and when the surface is reached, the player will bob there. Using the button does not increase swimming speed, despite widening the field of view; it will increase underwater walking speed, however, if the player is touching the ground.

Swimming in water is considerably slower against currents (see Current below), but faster when going with the current.

Most mobs that can stand will also swim any time they are in water, except for iron golems and undead mobs.

Spreading
Water will spread into nearby air blocks. Spreading water will extinguish fire and wash out plants, snow, torches, carpets, tripwire, rails, redstone and cobweb it flows into, dropping them as items.

Source blocks


A water source block will be created from a flowing block that is next to 2 or more other source blocks, and sitting on top of a solid block or another water source block. This is the rule that makes infinite water sources work. Using this, it is possible to create pools of still water by placing water source blocks in a confined area.

Dispensers loaded with a filled bucket will place a water source block in an empty block in front of them when activated. A dispenser loaded with an empty bucket and a water source just in front of it will suck the source into the bucket when activated.

In snowy biomes, water source blocks have a chance to turn into ice, and reappear when ice melts (except in the Nether). Ice will revert to water when broken if there is a block underneath.

Current
The current in a water block determines both what direction it will appear from its texture to be flowing, and what direction an entity such as a player or boat will float from that block.

Water with a current pushes players and mobs at a speed of about 1.39 meters per second, or 25 blocks every 18 seconds.

The horizontal current in a water block is based on a vector sum of the flows to and from that block from its 4 horizontal neighbors. For example, if a block receives water from the north and sends it both south and east, but borders a solid block on its west edge, then the current in that block will be south-southeast, because 2 southward flows (in and out) are combined with only 1 eastward flow (out). Thus, 16 horizontal directions are possible. If a branch in a channel is 2 blocks wide at its entrance, then entities will float into it rather than continuing in a straight line.

Light


Water reduces light by 3 for every block, as opposed to air's 1 per block for block lighting (but not sky lighting), so visibility lowers as the water gets deeper. Full dark is reached after only 5 blocks.

There are three ways of increasing underwater visibility: using a helmet with the Respiration enchantment, or using potions of Night Vision or Water Breathing.

In 1.13, the Respiration enchantment and the potion of Water Breathing will no longer increase the player's underwater visibility. The visibility also changes depending on the biome the player is in, and water reduce light by 1 every block deep, so only night vision is needed for better underwater visibility. Also, players can now obtain underwater Night Vision by activating a conduit.

Water and lava
Water and lava can produce stone, cobblestone, or obsidian based on how they interact.

Damaging mobs
Water will damage endermen, snow golems, and blazes.

Slower mining speed
Players with their head underwater take 5 times the normal amount of time to mine blocks while standing on the ground, or 25 times while not on the ground. However, with the Aqua Affinity enchantment, mining speed will be faster, which is 1× time while on the ground, and 5× time while not on the ground.

Drowning
Players and mobs (except fish, turtles, dolphins, squid, guardians, elder guardians, skeletons, wither skeletons, skeleton horse, zombie villager and iron golems) have a breath meter which lasts 15 seconds, after which they will take damage from drowning while their head is still below water, taking damage per second until they die.

Each level of the Respiration enchantment will add 15 seconds to the maximum time underwater, and will grant an x/(x+1) chance (where x is the Respiration level) of not taking damage after that time: 30 seconds and an average /second with Respiration I, 45 seconds and an average of $2/3$ damage/second with Respiration II, and 60 seconds and an average of $1/2$ damage/second with Respiration III.

If a husk drowns underwater, it will start to shake and eventually turn into a zombie. If a zombie drowns underwater, it will start to shake (similar to when a zombie villager is being cured), and eventually turn into a drowned.

Hardening concrete powder
When water comes into contact with concrete powder, the powder hardens into solid concrete.

Sponges
Water will be deleted when it comes into contact with a dry sponge, unless the water is occupied by kelp, seagrass or a conduit.

Water Bucket
A water bucket is bucket that is filled with water.

To fill an empty bucket with water, it on a water source block. The block is consumed in the process. Water buckets can also be filled by smelting a wet sponge in a furnace, with an empty bucket in the fuel slot. The bucket will be filled when the smelting process is complete.

a full water bucket on a solid block will place a water source block against that block, emptying the bucket. In the Nether, however, the water will evaporate (meaning a water block will not be placed).

A dispenser can also empty a water bucket. When a dispenser with a water bucket inside is activated, the dispenser will place a water block and the bucket inside will revert to an empty bucket.

Water buckets can be used to fill cauldrons.

Water buckets can be used on a fish to create a fish bucket.

ID
Water spends most of its time as stationary, rather than 'flowing' – regardless of its level, or whether it contains a current downwards or to the side. When specifically triggered by a block update, water will change to 'flowing', update its level, then change back to stationary. Water springs are generated as flowing, and oceans, lakes and rivers are generated as stationary. This happens before most types of generated structure are created, and the main cause of water "glitches" is that generated structures do not trigger a block update to let water flow into them.

Block data
If bit 0x8 is set, this liquid is "falling" and only spreads downward. At this level, the lower bits are essentially ignored, since this block is then at its highest fluid level.

The lower three bits are the fluid block's level. 0x0 is the highest fluid level (not necessarily filling the block - this depends on the neighboring fluid blocks above each upper corner of the block). Data values increase as the fluid level of the block drops: 0x1 is next highest, 0x2 lower, on through 0x7, the lowest fluid level. Along a line on a flat plane, water drops one level per meter from the source.

Trivia

 * While underwater, the player's FOV (field of vision) is lowered by 10 to simulate light refraction.
 * The old water texture can still be found in the assets and is used in the game if the player is underwater.
 * In Bedrock Edition, the texture of water changes from turquoise to pale blue when viewed from far away.
 * Water buckets can be used to break end portal blocks by placing the water on the side of a block corresponding to a side of an end portal block.
 * Water will display a strange, glitchy flowing texture if adjacent to certain transparent blocks. Despite the glitchy appearance, this is actually a completely intentional feature.
 * Water does not prevent explosions from activating. This effect is due to water's very high blast resistance, causing it to absorb any normal blasts, with the exception is explosions from Underwater TNT.