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Fresh Water Tank Leak... Catalina 310

Discussion in 'Ask A Catalina Owner' started by SailFysh, Jun 8, 2018. Add this thread to a FAQ

  1. SailFysh


    Joined Aug 23, 2014
    166 posts, 5 likes
    Catalina 310
    US Guntersville, Alabama
    Hello all,

    We have a 2003 Catalina 310 with a small leak from the fresh water tank or connection. The bow end of the bilge slowly fills and I cannot trace it from the small access door in the vberth floor. Looking beneath the mattress all I can see is the freshwater tank. Has anyone removed the tank? Looks like a chore to me but what isn't a chore on a boat?
    I am sure it is coming from the freshwater tank because I dyed the water red when I filled the tank and it showed up in the bilge 2 days later.

    The only other water I see coming into our bilge is from the AC drain hose when it is running.




  2. Apex


    Joined Jun 19, 2013
    753 posts, 87 likes
    Oday 28
    US Traverse City
    Any drawers in the V-Berth that may provide access? Other idea includes expanding the size of the top access, and placing a larger cover. No particular boat experience, but my thoughts are in modifying so that future work is easier.

  3. leo310


    Joined Dec 15, 2006
    84 posts, 29 likes
    Catalina Catlina 310
    CA Campbell River BC
    Is this leak after you filled the tank or is it after you got the tank level down? On ours we have only 3 connections 1 fill 1 vent and 1 discharge located center aft of tank, you can see it when you remove the 2 bottom drawers, the other 2 are forward. You may want to check the top inspection port as it may leak when over filling.

  4. SailFysh


    Joined Aug 23, 2014
    166 posts, 5 likes
    Catalina 310
    US Guntersville, Alabama
    Thanks. Will inspect these areas closer this weekend.

  5. JK_Boston_Catalina310


    Joined Nov 18, 2010
    1,954 posts, 79 likes
    Catalina 310
    US Hingham, MA
    Check out this thread on the 310 owners forum. There are some pictures of the tank.
    Are you sure its fresh water? I use a salinity meter to test my bilge water to see what it is. They are about $50 on Amazon. I think they have some test strips for less too. Or you could do it the old fashion way and taste it.

  6. buddy0


    Joined Sep 17, 2014
    1 posts, 0 likes
    Catalina 30
    US Oriental, NC
    I recently found the leak in one of the freshwater tanks in my 1984 Catalina 30. I also put some dye in the tank to verify the leak was coming from the tank.

    I could not find the leak with the tank in the boat. Even after pulling it I could not find the leak until I finally pressurized the tank and found a crack about 3" from the bottom on the side. I was surprised it wasn't at a connection. When under pressure, water would just weep through the crack. It seemed to leak faster in the boat. It must have been a combination of the weight of the water in the tank and a pressure point near the crack.

    I've done a fair amount of research of how to fix it but have not found anything that I am ready to try yet. Seems like welding it, with or without some more of the same type of plastic, is the way to go. A skilled hand may be able to do it with a hot knife or iron. There are also fairly expensive tools for this. To much heat and you have a bigger hole. Right now I am just using the extra space for other stuff. Anyone have any experience fixing a leak in a tank like this?


  7. Peggie Hall HeadMistress

    Peggie Hall HeadMistress

    Joined Dec 2, 1997
    6,850 posts, 519 likes
    - -
    US LIttle Rock
    There's a bit more to heat welding than just melting some new PE into the also have to melt the edges of the crack so that the new material blends with it to form a continuous blend with the tank wall. A new tank is the only solution that's likely to be permanent. You can get an identical replacement from Ronco Plastics Ronco Plastics marine Tanks They've been the Catalina's OEM supplier for water and waste tanks for decades. Give 'em call with the with size and model year for your boat...I think you'll be pleasantly surprised with the price compared to what Catalina would charge you to get it from them.

    "If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

  8. SailFysh


    Joined Aug 23, 2014
    166 posts, 5 likes
    Catalina 310
    US Guntersville, Alabama
    Yes it is definitely from the freshwater tank. Still trying to find exactly where the leak is.
    Thanks for the tips.

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