Water is a useful example of why a published cup weight and a physical unit definition are different things. BatchLadle keeps the source recipe convention separate from the reported liquid-water density.
Read the temperature condition
The FAO/INFOODS record used here is for liquid water at 20°C. Its density is a reported value with that condition, not an ice reference or an exact value for every temperature.
Use it for an approximate kitchen mass–volume conversion within its scope. A fixed volume-unit conversion, such as millilitres to a defined cup, does not need water density at all.
Do not derive a cup from a recipe weight
King Arthur’s water cup is retained as a rounded recipe convention. Its gram value is not used to infer the source cup’s millilitres or to replace a physical density.
Choose the source explicitly before converting. A change from US to metric should change the requested unit, not silently exchange a recipe convention for another reference.
Use water clearly in a baker’s formula
Water entered as a separate ingredient contributes to the identified water total. Add declared starter water where relevant, and include the starter’s flour in the flour basis.
If the recipe already supplies water by weight, keep that weight. This avoids an unnecessary round trip through a volume estimate while changing the dough size.