Supplied by Dixon
Remember that water added to a battery is less dense than the dilute acid already in the cell. Water will sit on top of the electrolyte until it is mixed in by the bubbling, gassing behavior of the cell during a full charge cycle. This fact is important if you take hydrometer readings of the electrolyte; the reading will not be accurate after watering until after the following charge. Also note that batteries exposed to extremely low temperatures for long periods can be damaged by freezing unless they are fully charged, especially after any water additions.
Water available in 1L and 25L bottles