I didn't say anything contradicting this or it isn't somethiing I didn't knew. But thanks anyway for pointing to it. My points were based on the numbers without knowing that palace did gave an additional +1 housing. Without the additional housing from the palace you would have 3 housing for a coastal capital without fresh water. Since the housing penalty starts at the point when you have filled the housing capacity up to 1 less than available, 3 housing for a coastal capital without fresh water would have meant you would already have a -50% growth penalty after reaching pop 2 and -75% growth penalty after reaching pop 3 and beyond till the hard cap. This is of course with the assumption that at that point no additional housing from farms or granary is obtained, which is highly likely since normally you don't have the tech for granary yet or build a builder for farms or pastures/plantations (which also require a tech) right away. But since the palace provides an additional housing the penalty starts at pop 3 for the coastal capital without fresh water. This gives some more time for taking measures for the penalty cap. But a coastal capital still has its other disadvantages.
For an inland capital without fresh water apparently the housing is 3, 1 from palace and 2 for settling inland with fresh water. So you have to take already measures very quickly since the penalty starts at pop 2. If you do this by building farms afaik you have to work the farmed tiles too, to take benefit of the housing. So that probably means giving up other tiles with possibly 4 yields (hills + woods/rainforest) for a farmed tile with 3 yields.
My opinion is that settling a capital at the coast or inland without fresh water has enough disadvantages to either move the settler to a fresh water in the first turn or possibly reroll
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That is true. Not only do farms give housing, but also pastures and plantations. Others have also mentioned buildings that do give housing. So the effect of the aquaduct district for housing isn't essential anymore at the point it is available.