Water

Water is a natural fluid.

Obtaining
Water itself cannot be obtained as item no matter what, but can be retrieved with a bucket.

Natural generation


Water naturally generates in the Overworld in oceans, lakes, rivers, springs, and village and desert wells.

Spreading
Water spreads across surfaces in a slightly more realistic way but cannot spread on top of another water block. Water source blocks create a spring which generates flowing or falling water. When a spring is destroyed, all flowing water created from it will slowly dry up. If there is a hole six blocks or fewer from the point of origin, the water will tend to flow in that direction. Source blocks and falling water that has landed on a solid block will always flow in at least one direction unless restricted. Water will travel a distance of 8 blocks with the counter resetting to 0 every time it lands on a lower level. If a block next to a water source block is destroyed, the water will immediately flow in that direction unless there was a block beneath the destroyed block. However, water may not notice changes in terrain and may need to have a block next to it updated so it can re-calculate its flowth.

Spreading water will extinguish fire and wash out plants, snow, torches, carpets, tripwire, rails and cobweb (with them dropping as items) it flows into.

Source blocks


The water source blocks can appear horizontally and orthogonally next to 2 or more other source blocks, on top of solid blocks or other water source blocks. This is the principle the infinite water generators work on.

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.

The horizontal current in a flowing-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.

Flowing water pushes mobs at a speed of about 1.39 meters per second, or 25 blocks every 18 seconds.

Light


Water reduces light by 2 for every block, in addition to normal dispersion, so visibility lowers as the water gets deeper.

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

Water buckets
Water bucket is a variation of buckets that is filled with water.

To fill a bucket with water, it on a water source block. The block is consumed in the process. the full bucket on a solid block will place a water source against to its pressed side.

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, lava drops one in the nether and two everywhere else.

The stationary versions of each fluid are "stable" and currently not being checked by the engine for further level changes.

Videos
Note: The video states that "Infinite water sources are found all over the world in shallower areas." Ever since the update, this is no longer the case — water source blocks form even if there isn't a solid block under them, as long as there is a water source block under it, meaning even deep bodies of water can be used as infinite water sources.

Trivia

 * While underwater, the player's FOV (field of vision) is lowered by 10 to simulate light refraction.
 * Blocks take 5 times as long to mine if the player's head is underwater, which is indicated by the presence of the respiration bar, and 25 times as long if they are both underwater and not grounded.
 * Water will freeze into ice in snowy biomes.
 * Water flows at 0.25 seconds per block (1/4 second/Block), taking it approximately 1.75 second to reach the maximum water range on a flat surface (7 blocks excluding the source).