I'm just a newb, but I tend to skip that. Like 120 production (on Epic) and maint. of 2 resources for a gain of 3? No thanks, I have better things to build early.
Build an extra trading post as suggested above and work it with the free food
Which takes an extra population, which itself takes a large investment of food, and costs happiness.
Later on when you have more happiness and you want to grow your city, you can also manage that a lot faster with watermills already in place.
I think it is this:
1 + 4 is 5 x 1.15 (workshop bonus) = 5.75
Then 5.75 x rail bonus (50% right?) = 8.62 for 2
Now someone pipe up and tell me what the bonuses should really be so I can edit this and fix it.
*edit* Bleh, already found a problem. Maintence costs for workshop and rail connection also need to be figured in unless of course you are planning on always having workshops and rail connections and the only question is to Watermill or not to Watermill.
The question is this: what can you build that is more effective with 70? If you're going vertical, an Aqueduct is going to yield a lot more Food than the Water Mill, making it well worth the extra 30 investment. If you're going horizontal, Maritimes are much cheaper than putting Water Mills everywhere, and 70 now for 1 per turn later is terrible return on investment.
Aqueducts come much later, and you dont need to spend gold on buying Watermills, they are easy to build after a monument and libray.
Heres my second try at an early 4 city REX, it is very easy to build watermills and granaries before you get to aqueducts.
You built Watermills before Granaries in cities with wheat and/or bananas. Granary would be superiour in those cases. Aqueducts might come later but there are other things to invest into aswell than just food buildings. No, I am with Martin on this one. Maritimes are superior and gold is more flexible to have, the maintenance is too high IMO.
Aqueducts come much later, and you dont need to spend gold on buying Watermills, they are easy to build after a monument and libray.
In a vertical situation, the early build order is cluttered because you're building relevant specialist buildings and the setup buildings for National Wonders. There just isn't room for a Water Mill in there until later, and by then Aqueducts are both available and needed.
By your logic, a Granary is always a better choice whenever there is a single Deer or Wheat tile in the radius.
Either way, it seems really curious and out-of-place that a basic ancient era building like this costs not 1, but 2 gpt. All the contemporaries - Monuments, Stables, Granaries are 1 gpt.
Good observation
Or maybe +2 hammers and 2 maintenance.