Fresh Water Tank Maintenance

Discussion in 'General Maintenance/Repair Questions' started by Pairadocs, Aug 22, 2019.

  1. Pairadocs

    Pairadocs Member

    Jan 15, 2016
    Fenton, MI/Tawas City, MI
    400 Sundancer 1998
    3116 Caterpillar
    We really don't drink the water from our fresh water tank, but it seems like I am now seeing black streaks in the heads. They are appearing every couple weeks after cleaning. I have read about adding a small amount of bleach in the tank to clean it, but I am not sure how good that is for seals an pumps. Any thoughts on the best way to clean and maintain your fresh water tank? Thanks, Alan
  2. Phasma

    Phasma Phasma2128 PLATINUM Sponsor

    Sep 17, 2016
    West Michigan
    2003 360 Sundancer
    Mercruiser 8.1s Horizon
    I generally dump a bottle of tank cleaner into the tank every month or two. I buy it in the RV section at Walmart.
    susanandlance likes this.
  3. Pairadocs

    Pairadocs Member

    Jan 15, 2016
    Fenton, MI/Tawas City, MI
    400 Sundancer 1998
    3116 Caterpillar
  4. Golfman25

    Golfman25 Well-Known Member

    Sep 12, 2009
    If you use bleach, only use a small amount -- a few ounces. Run the system for a minute. Then pressurize the system for an hour or so. Drain and refill the take a few times to rinse.
  5. b_arrington

    b_arrington Well-Known Member GOLD Sponsor

    Feb 21, 2007
    Setauket, NY
    2018 Back Cove 34
    Cummins QSB 6.7 480
    For regular maintenance use something like Aquabon or Camco water freshener. Only need a little - like 1 oz per 30 gallons or so. Works very well to keep water in a clean tank sweet.
  6. Leardriver

    Leardriver Active Member

    May 24, 2016
    Denver, CO
    2004 270 Sundeck 8.1 Bravo III
    5.0, 5.7, 6.2 8.1 Bravo III over the years
    Bleach works. it needs so sit for 4 hours or more. Like Golfman mentioned, a small amount like less than 1/2 cup in 5 gallons, and then don't let any drip on your carpets while you are flushing. For pure cheapness and efficiency, it is great.
  7. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    I use both methods above.

    When I place the fresh water system in service at the beginning of the season I use the bleach method and flush the system a few times ........ then I use Camco water freshener through out the season.
  8. Ezsteps

    Ezsteps Well-Known Member PLATINUM Sponsor

    Nov 14, 2015
    Lake St. Clair-- Michigan (MacRay Harbor)
    1999 400 Sundancer, YL310 Zodiac
    7.4 Mercuisers Horizons 380 hp ea., 9.9 hp Mercury
    +1 on the Camco. I use it everytime I put water in the tank throughout the year. Note: I only fill my water tank to 1/2 full. You probably know this but it is advised to never fill "our" fresh water tank full. They tend to crack in the corner of the "L" shape.
  9. Jimmy Buoy

    Jimmy Buoy Well-Known Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    Black streaks in your head are probably caused more by black seals deteriorating on your fresh water valve than your potable water tank. If you bleach the system, just be careful not to leave the bleach in the lines more than a day or so since it will start degrading those black rubber seals.
    JVM225 likes this.
  10. carterchapman

    carterchapman Well-Known Member TECHNICAL Contributor SILVER Sponsor

    Mar 25, 2008
    Lake Chickamauga/Marietta, GA/Ft. Myers, FL
    2006 Sea Ray 58 DB
    MAN CRM V8-900s, Twin Disc Drives; Onan 21.5 Generator
    I posted in another thread how to use clorox to clean/sanitize your tank - the procedure should be in your Owner's Manual. I am careful not to flush any of the clorox treated water through my heads as the clorox would not be good for the bacteria that are working in the holding tank...
    JVM225 likes this.
  11. Boat Guy

    Boat Guy Well-Known Member

    Personally, I would investigate the black streaks. I wouldn't focus on the tank until I learned what was causing them....

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