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Fresh Water Tank Fitting Installation

Discussion in 'Post Yacht' started by Soulstice, May 8, 2023.

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  1. Soulstice, May 8, 2023
    #1
    Soulstice

    Soulstice Member

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    Portsmouth, Ri
    I am installing a watermaker on my 50 Post and one challenge I am having is how to fill the tank with the new fresh water. I would like to use a sanitary bulkhead fitting with a push to connect fitting threaded into it. The problem I am having is that there is no way to install a fitting as there is nothing on the tank to open for access. It appears that some of the other ports were added to the tank (I assume) by cutting a a hole in the tank and and then glueing a larger patch which has the fitting in it over the cutout.

    If this is the case, I could use a hole saw for the top, add the bulkhead fitting and then glue a slightly larger polypropylene circle over the new hole. I can’t think of a better way right now so my questions are…

    1. has anyone added fittings to their tank and how did you go about it?

    2. what did you use to glue/seal to polypropylene?

    Attached Files:

  2. Capt Ralph, May 8, 2023
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    When I can not find a tank top fitting to use, I added a T to the fill or vent connects at the tank.
    Don't forget a potable compatible check valve to prevent a flooded tank from flowing back to the RO system. Now you can leave the charcoal filter open when the RO is not in use.
    I use potable water compliant, Nylon/plastic check valves from McMaster-Carr.
    chesapeake46 likes this.
  3. Pascal, May 9, 2023
    #3
    Pascal

    Pascal Senior Member

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    I wouldn’t cut a new fitting into the tank but Tee in the filler hose near the tank.

    the check valve is a good point but I don’t think I have ever seen one on WM installation diagrams. Unless maybe it’s built in the output carbon filter housing.
  4. Capt Ralph, May 9, 2023
    #4
    Capt Ralph

    Capt Ralph Senior Member

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    Learned the hard way a few times.
    Owners leave the filters apart when the RO is not in use.
    Fill their water tanks. next day call me rather upset about a leak.

    I've never found this in a WM install manual either but if I do the install; it gets done anyway now days..
  5. Soulstice, May 17, 2023
    #5
    Soulstice

    Soulstice Member

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    Location:
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    Thank you for your feedback as this makes logical sense to me. It is pretty straight forward for me to get to the fill line and add a tee.

    Regarding back-feeding, I have a filter after the RO membrane. Is a one way valve between the tank needed as I would think it would need decent pressure to go backwards through the water filter system especially when I have an overfill vent line on the top of the tank. I am glad I asked this questions as I hadn’t thought about that potential issue.
  6. Capt Ralph, May 17, 2023
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    If you leave that filter off, When the tank is filled from dock side, water will leak in the boat.
    If you leave the final charcoal filter together, water may stale while sitting in between uses.
    The nylon valves we use offer little restrictions and does not effect operations.
    Installed between the filter and tank.

    Example;
    https://www.mcmaster.com/6079T83/

    In between seasons, we install our charcoal filter a few minutes after the WM diverts to the potable tank also.
    Just a lil more help to purge the hose from old water.