Water continues to increase in self-sustaining bathroom/toilet

This is not a bug. The Lavatory adds 6.7kg of polluted water with each use. This is essentially to account for the waste that the duplicants are adding to the polluted water.

https://oxygennotincluded.gamepedia.com/Lavatory

Dupes consume water, like us humans. And where does this water go? Sweat and pee. Of course it adds to lavatory. Self sustaining only works with showers. With lavatorys you have to vent the excess.

This is not bug by itself, but if look at all picture: dupes dont directly consume water - they consume food, but you can cook food without water, you can grow some plants for food without water, so you can generate water out of nowhere - this is wrong somehow.

Not talking that: "The Lavatory adds 6.7kg of polluted water with each use", but when dupe "made mess" it creates only 2kg of polluted water(i checked just right now), numbers not fitting... Water Sieve make from 5kg of polluted water 5kg clear water, consume 1kg of sand for this and return only 0.2kg of polluted dirt, so we losing sand to nowhere...