It fills itself
The reserve refills every hour with nothing to do. A full reserve does not overflow, and lowering the cap never removes water already stored.
The water pump fills on its own the reserve used to water the farm. Every player owns it at tier 1, and each tier widens the reserve and speeds up the refill.
The reserve refills every hour with nothing to do. A full reserve does not overflow, and lowering the cap never removes water already stored.
Watering costs 10 water on a bare tile, then 15, 20 and 25 at the tile’s tiers 1 to 3. When water runs short, the highest tiles are served first.
Tier 5 sustains exactly 100 tiles all at tier 3: its reserve covers a full pass and its refill keeps pace with growth.