Hi xavpil.
I think we can clear this up but as dj pointed out a little more information (for us and for you) is needed.
1.
freshwater tank bow
The Jeanneau Sun Odyssey 419 should have two tanks.
This manual page 37
https://horizonyachtcharters.com/wp...410-2020-Tola-Sunrise-Operations-Manual-1.pdf
That should be the first thing for you to confirm.
2.
my water maker is stern
Is this a new water maker that you are fitting or is it on the boat already?
What does the water maker manual say about the length/ slope/ diameter of hose concerning the fresh water from the maker to the tank?
3.
Long distance to run the “final” tube of fresh water
Are you concerned about this because of the length of the run or that you will have to drill holes in bulkheads or make other modifications to run it?
See water maker manual.
4.
1- Where/how do I connect the fresh water line that comes from the water maker On the freshwater tank?
Again the water maker manual will give you a recommendation for connecting to your tank.
You need to check whether your tank has a spare nipple for an independent water maker fresh water inlet.
If so, that is what I would use.
5. 2- Or do I connect the line with a T connection , closer to intake from the deck?
That sound doable. If you go that way you will need to cut the inlet hose up high, add a tee fitting and then a line to the water maker. I would add a check valve or one way valve on that line near the connection to prevent back flow from the filler line to the water maker fresh water outlet line.
gary
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