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 that generates abundantly in the Overworld.

Appearance
The textures in Bedrock Edition are somewhat different from those in Java Edition, shown here for comparison.

Obtaining
Water blocks do not exist as items, but water can be collected by using a bucket on a water source block or a full cauldron.

In the Bedrock Edition, it may be obtained as an item via inventory editing.

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

In the Bedrock Edition, water also generates as part of underwater ruins with loot chests, but only two water blocks generate: It is unknown whether this is intentional or not. This is not the case in the Java Edition.
 * One water block generates inside the loot chest, making it a waterlogged loot chest.
 * The other water block generates on top of the loot chest.

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 up and down. As of the 1.13 update controls were changed, however, now the run button can be used to put the player in "swim mode" when the player is completely submerged in water, and the mouse can then be used to direct movement. When in swim mode, the player is horizontal and therefore only one (1) block high. When not in swim mode, the jump and crouch buttons can be used to raise and lower the player through the water, significantly faster than in previous updates.

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. This can lead to drowning if the water is falling from above.

Spreading
Water will spread horizontally and downwards into nearby air blocks. Water can spread downwards until it reaches the bottom of the world, and 7 blocks away horizontally from a source block on a flat surface. Water spreads at a rate of 1 block every 5 game ticks, or 4 blocks per second.

Spreading water will extinguish fire and wash away certain types of items or placed blocks, causing them to drop as items and then carrying them along in the flow until the edge of the spread. Affected items include plants (except trees), snow, torches, carpets, rails, redstone dust and some other redstone components, cobweb, end rods, mob heads, and flower pots.

Source blocks
A water source block will be created from a flowing block that is horizontally next to 2 or more other source blocks, and sitting on top of a solid block or another water source block. This allows infinite water sources, where collecting a source block will cause another source block to immediately form at the same location. 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 right 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 if directly under the sky. Ice blocks under brighter light levels will melt back into water source blocks (except in the Nether). Ice will revert to water when broken if there is a water block underneath.

Current
The current in a water block determines both the direction it will appear to be flowing, and the direction an entity such as a player or boat will be pushed 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
In the Bedrock Edition, every block of water reduces light by 1 extra level (in addition to the normal fading-out of light). In Java Edition, water does not cause any additional decrease for block light, but will diffuse sky light, causing it to fade out as it travels downwards. Underwater visibility changes depending on the biome the player is in. The Night Vision and Conduit Power effects increase underwater visibility.

Color
Water has several colors, depending on the terrain.

Java Edition

 * Warm oceans biome have a light green color.
 * Lukewarm oceans and jungles have a  aquamarine color.
 * Regular oceans, most rivers, lakes, medium/lush (except jungles), neutral and other biomes and have a blue color.
 * Cold oceans have a dark indigo color.
 * Frozen oceans, frozen rivers have a dark purple color.
 * Swamps have a light and dull green-gray color.
 * Other biomes not listed above have a blue color.

Water and lava
Water and lava can produce stone, cobblestone, or obsidian based on how they interact. If the water touches a lava source, the lava turns to obsidian. If both touch each other while flowing, cobblestone is made and no sources are removed, and if lava hits a water source, the water source turns to stone.

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 if they are wearing a helmet with the Aqua Affinity enchantment, mining underwater will take the same time as on land while on the ground, and 5× time while not on the ground.

Drowning
Players and mobs (except fish, turtles, dolphins, squid, guardians, elder guardians, undeads and iron golems) have a breath meter that lasts 15 seconds. After they run out of breath, they will take drowning damage every second until they die or surface.

Each level of the Respiration enchantment will add 15 seconds to the breath meter and 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 and eventually turn into a drowned.

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

Sponges
When a dry sponge comes into contact with a water source or flowing block, it will be turned into a wet sponge and all of the water within 3 to 5 blocks in all directions will be absorbed. Kelp and lily pads within the absorbed water blocks will be destroyed and drop as items, and seagrass will be destroyed without dropping anything. Mobs that take damage out of water will be affected as a side-effect.

Sponges do not absorb water from waterlogged blocks, nor water that comes into contact by flowing back in from outside the area of absorption. For instance, placing a sponge 4 or more blocks from a single water source will remove the flowing water in the area of effect, but as the flow from the source resumes it will not be affected by the sponge.

A sponge instantly absorbs nearby water when it is placed next to water or when water comes into contact with it (by being placed next to the sponge, or by flowing towards it). A sponge absorbs water around itself (water source blocks or flowing water) out to a taxicab distance of 7 in all directions (including up and down), but won't absorb more than 65 blocks of water (water closest to the sponge will be absorbed first). The absorption only propagates from water to water and won't "jump over" non-water blocks (including air).

Dripping
Water above a non-transparent block (does not include stairs, fences, and slabs) produces dripping particles on the underside of that block. These droplets are purely aesthetic.

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.
 * 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 of explosions from Underwater TNT.