Marine Water Tanks

These NSF and FDA compliant marine water storage tanks are made to be incredibly strong, nearly unbreakable, and are very affordable. Plastic marine water tanks (poly) are available in nearly every size and shape. Made from one piece of thick poly, there are no seams so less opportunity for leaking, and made with a rotomold process for superior strength. You won’t find better-made marine fresh water tanks for the price. 

Made from one piece to form 3/8” thick walls using a roto-mold process to create a seamless holding tank superior in strength and performance. These custom fitted marine water tanks are built to go the distance.   

*Note: Customize the placement of the fittings when you place the order.  We spin-weld the fittings to ensure your holding tank is securely connected to your plumbing.

  • Complies with NSF 61, FDA Reg CFR 177.1520, and Coast Guard Standards
  • Made from virgin polyethylene (poly) resins
  • Seamless tank made from one piece (less likely to break or leak)
  • 3/8” thick tank walls
  • Customized fitting placement
  • Spin weld fittings
  • Outlasts the competition

For use as marine water tanks, marine fresh water tanks, plastic marine water tanks, poly marine water tanks, custom marine water tanks, and more!

We have 100’s of sizes ranging from 2 gallons, 40 gallons, 50 gallons, 100 gallon marine water tanks.  They range in size up to 250 gallons for these poly marine fresh water tanks.

Looking for something else? Chances are, we have it, and at affordable prices too!  Just call us and ask!

Pick the size and shape you need from the list. Mark up the drawing with your fittings placement. Call us with any questions!

Shop by Category

Marine Water Tanks

  • 21 Gallon Marine Water Tank MW-555. Technical drawing of a polyethylene water tank designed for marine vessels.

    21 Gallon Marine Water Tank MW-555

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 21 Gallon Marine Water Tank, Part# MW-555, is engineered to meet the requirements of mobile...

    MSRP: $364.15
    $346.22
    Add to Cart
  • 21 Gallon Marine Water Tank MW-526. Technical drawing of a polyethylene water tank designed for marine vessels.

    21 Gallon Marine Water Tank MW-526

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 21 Gallon Marine Water Tank, Part# MW-526, is engineered to meet the requirements of mobile...

    MSRP: $263.54
    $250.57
    Add to Cart
  • 21 Gallon Marine Water Tank MW-413. Technical drawing of a polyethylene water tank designed for marine vessels.

    21 Gallon Marine Water Tank MW-413

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 21 Gallon Marine Water Tank, Part# MW-413, is engineered to meet the requirements of mobile...

    MSRP: $275.15
    $261.61
    Add to Cart
  • 21 Gallon Marine Water Tank MW-371. Technical drawing of a polyethylene water tank designed for marine vessels.

    21 Gallon Marine Water Tank MW-371

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 21 Gallon Marine Water Tank, Part# MW-371, is engineered to meet the requirements of mobile...

    MSRP: $265.29
    $252.23
    Add to Cart
  • 21 Gallon Marine Water Tank MW-320. Technical drawing of a polyethylene water tank designed for marine vessels.

    21 Gallon Marine Water Tank MW-320

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 21 Gallon Marine Water Tank, Part# MW-320, is engineered to meet the requirements of mobile...

    MSRP: $236.70
    $225.04
    Add to Cart
  • An image of a 65 Gallon RV Fresh Water Tank | B283

    22 Gallon Marine Fresh Water Tank | B473

    This 22-gallon Ronco marine fresh water tank (B473) is built for onboard potable water storage on boats and watercraft. Measuring 43" x 17" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $339.43
    Add to Cart
  • An image of a 30 Gallon Marine Holding Tank | B488

    22 Gallon Marine Fresh Water Tank | B468

    This 22-gallon Ronco marine fresh water tank (B468) is built for onboard potable water storage on boats and watercraft. Measuring 23 5/8" x 23 5/8" x 12 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $397.67
    Add to Cart
  • An image of a 135 Gallon Marine Holding Tank | B300

    22 Gallon Marine Fresh Water Tank | B463

    This 22-gallon Ronco marine fresh water tank (B463) is built for onboard potable water storage on boats and watercraft. Measuring 28" x 17 3/4" x 13 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $397.67
    Add to Cart
  • An image of a 50 Gallon PE Ronco White Rectangular Open Top Tank | 30X24X18PE

    22 Gallon Marine Fresh Water Tank | B430

    This 22-gallon Ronco marine fresh water tank (B430) is built for onboard potable water storage on boats and watercraft. Measuring 45 1/2" x 11 1/2" x 11 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $268.13
    Add to Cart
  • An image of a 16 Gallon PE Ronco White Rectangular Open Top Tank | 30X12X12PE

    22 Gallon Marine Fresh Water Tank | B348

    This 22-gallon Ronco marine fresh water tank (B348) is built for onboard potable water storage on boats and watercraft. Measuring 34 1/4" x 11 1/4" x 17", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $327.38
    Add to Cart
  • An image of a 40 Gallon Marine Fresh Water Tank | B241

    22 Gallon Marine Fresh Water Tank | B337

    This 22-gallon Ronco marine fresh water tank (B337) is built for onboard potable water storage on boats and watercraft. Measuring 36" x 16" x 11 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $327.38
    Add to Cart
  • An image of a 3 Gallon Marine Holding Tank | B267

    22 Gallon Marine Fresh Water Tank | B276

    This 22-gallon Ronco marine fresh water tank (B276) is built for onboard potable water storage on boats and watercraft. Measuring 23" x 16 7/8" x 14 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $268.13
    Add to Cart
  • An image of a 38 Gallon Marine Holding Tank | B403

    22 Gallon Marine Fresh Water Tank | B207

    This 22-gallon Ronco marine fresh water tank (B207) is built for onboard potable water storage on boats and watercraft. Measuring 27 1/2" x 20 1/2" x 14", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $362.53
    Add to Cart
  • An image of a 40 Gallon Marine Holding Tank | B241

    22 Gallon Marine Fresh Water Tank | B149

    This 22-gallon Ronco marine fresh water tank (B149) is built for onboard potable water storage on boats and watercraft. Measuring 32 1/4" x 16" x 15 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $327.38
    Add to Cart
  • An image of a 18 Gallon Marine Fresh Water Tank | B129

    22 Gallon Marine Fresh Water Tank | B134

    This 22-gallon Ronco marine fresh water tank (B134) is built for onboard potable water storage on boats and watercraft. Measuring 48" x 13" x 12 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $339.43
    Add to Cart
  • An image of a 110 Gallon PP Ronco White Rectangular Open Top Tank | 48X24X24PP

    22 Gallon Marine Fresh Water Tank | B128

    This 22-gallon Ronco marine fresh water tank (B128) is built for onboard potable water storage on boats and watercraft. Measuring 34" x 12" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $268.13
    Add to Cart
  • An image of a 31 Gallon PE Ronco White Rectangular Open Top Tank | 18X18X24PE

    22 Gallon Marine Fresh Water Tank | B117

    This 22-gallon Ronco marine fresh water tank (B117) is built for onboard potable water storage on boats and watercraft. Measuring 29" x 9 1/2" x 20", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $304.28
    Add to Cart
  • 22 Gallon Marine Water Tank MW-509. Technical drawing of a polyethylene water tank designed for marine vessels.

    22 Gallon Marine Water Tank MW-509

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 22 Gallon Marine Water Tank, Part# MW-509, is engineered to meet the requirements of mobile...

    MSRP: $232.77
    $221.31
    Add to Cart
  • 22 Gallon Marine Water Tank MW-472. Technical drawing of a polyethylene water tank designed for marine vessels.

    22 Gallon Marine Water Tank MW-472

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 22 Gallon Marine Water Tank, Part# MW-472, is engineered to meet the requirements of mobile...

    MSRP: $243.86
    $231.85
    Add to Cart
  • 22 Gallon Marine Water Tank MW-414. Technical drawing of a polyethylene water tank designed for marine vessels.

    22 Gallon Marine Water Tank MW-414

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 22 Gallon Marine Water Tank, Part# MW-414, is engineered to meet the requirements of mobile...

    MSRP: $242.32
    $230.39
    Add to Cart
  • 22 Gallon Marine Water Tank MW-411. Technical drawing of a polyethylene water tank designed for marine vessels.

    22 Gallon Marine Water Tank MW-411

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 22 Gallon Marine Water Tank, Part# MW-411, is engineered to meet the requirements of mobile...

    MSRP: $265.18
    $252.12
    Add to Cart
  • An image of a 60 Gallon Marine Fresh Water Tank | B242

    23 Gallon Marine Fresh Water Tank | BOAT50W

    This 23-gallon Ronco marine fresh water tank (BOAT50W) is built for onboard potable water storage on boats and watercraft. Measuring 50" x 16" x 8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $327.38
    Add to Cart
  • An image of a 48 Gallon RV Fresh Water Tank | RVB491

    23 Gallon Marine Fresh Water Tank | B499

    This 23-gallon Ronco marine fresh water tank (B499) is built for onboard potable water storage on boats and watercraft. Measuring 36 1/8" x 20 1/8" x 11 7/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $304.28
    Add to Cart
  • An image of a 37 Gallon Marine Holding Tank | B489

    23 Gallon Marine Fresh Water Tank | B498

    This 23-gallon Ronco marine fresh water tank (B498) is built for onboard potable water storage on boats and watercraft. Measuring 20" x 23 3/4" x 19 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $386.63
    Add to Cart
  • An image of a 18 Gallon Marine Fresh Water Tank | B104

    23 Gallon Marine Fresh Water Tank | B450

    This 23-gallon Ronco marine fresh water tank (B450) is built for onboard potable water storage on boats and watercraft. Measuring 44 1/2" x 12 1/2" x 11 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $291.22
    Add to Cart
  • An image of a 25 Gallon Marine Holding Tank | B470

    23 Gallon Marine Fresh Water Tank | B429

    This 23-gallon Ronco marine fresh water tank (B429) is built for onboard potable water storage on boats and watercraft. Measuring 20" x 23" x 15", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $385.62
    Add to Cart
  • An image of a 45 Gallon Marine Holding Tank | B317

    23 Gallon Marine Fresh Water Tank | B378

    This 23-gallon Ronco marine fresh water tank (B378) is built for onboard potable water storage on boats and watercraft. Measuring 40" x 18" x 8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $291.22
    Add to Cart
  • An image of a 32 Gallon Marine Fresh Water Tank | B316

    23 Gallon Marine Fresh Water Tank | B172

    This 23-gallon Ronco marine fresh water tank (B172) is built for onboard potable water storage on boats and watercraft. Measuring 23" x 18" x 16", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $281.18
    Add to Cart
  • An image of a 39 Gallon Marine Fresh Water Tank | B469

    23 Gallon Marine Fresh Water Tank | B142

    This 23-gallon Ronco marine fresh water tank (B142) is built for onboard potable water storage on boats and watercraft. Measuring 29" x 23" x 12 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $304.28
    Add to Cart
  • An image of a 32 Gallon Marine Holding Tank | B316

    23 Gallon Marine Fresh Water Tank | B136

    This 23-gallon Ronco marine fresh water tank (B136) is built for onboard potable water storage on boats and watercraft. Measuring 23" x 18" x 16 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $281.18
    Add to Cart
  • 23 Gallon Marine Water Tank MW-528. Technical drawing of a polyethylene water tank designed for marine vessels.

    23 Gallon Marine Water Tank MW-528

    This tank ships in 6-8 weeks. Custom fitting placement is not available at this time. It can be ordered blank, or blank with a DIY Fitting Kit Custom Roto-Mold 23 Gallon Marine Water Tank, Part# MW-528, is engineered to meet the requirements of mobile...

    MSRP: $458.94
    $436.35
    Add to Cart
  • An image of a 80 Gallon Marine Holding Tank | B367

    24 Gallon Marine Fresh Water Tank | B564

    This 24-gallon Ronco marine fresh water tank (B564) is built for onboard potable water storage on boats and watercraft. Measuring 28 3/4" x 19 3/4" x 11", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $386.63
    Add to Cart