You're overthinking this. Water has a cycle in nature. It evaporates, makes clouds, then condenses and creates precipitations. Over one year, the average preci

You're overthinking this. Water has a cycle in nature. It evaporates, makes clouds, then condenses and creates precipitations. Over one year, the average precipitation level across the whole planet is about 1 meter (1000 millimeters). Since the Earth area is 500 million km2, then every single year about 500 million cubic kilometers of water evaporate and then rain down. We are not in any danger to contribute meaningfully to this. The theoretical minimum energy to electrolyze 1 liter of water is 16 MJ. Or 16 billion GJ per km3. This is the same as 4444 TWh per km3. The entire world electricity production per year is about 22 TWh, so if we use all of it to electrolyze water we would use up a grand total of 5 cubic kilometers of water. Which later would be released in the atmosphere as water vapor, when we burn up the Hydrogen. That means we would add 1 part in 100 million to the annual water cycle in nature.