Occasional increase in water per tick

[cornelius_4]

Sometimes my water goes up in a 6 minute tick rather than down. Other times it will be excluded while piety, rest and food still goes down. These are probably not features, even if it is very inconsequential I think.

[The Rambling Midget]

This is a feature. Settlements can pay extra resources to have water go up with each tick. If your water is excluded while you're in a settlement with this feature, then it's already at 100%.