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

  • 53 Gallon Marine Water Tank MW-442. Technical drawing of a polyethylene water tank designed for marine vessels.

    53 Gallon Marine Water Tank MW-442

    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 53 Gallon Marine Water Tank, Part# MW-442, is engineered to meet the requirements of mobile...

    MSRP: $620.75
    $590.19
    Add to Cart
  • An image of a 45 Gallon Marine Holding Tank | B452

    54 Gallon Marine Fresh Water Tank | B472

    This 54-gallon Ronco marine fresh water tank (B472) is built for onboard potable water storage on boats and watercraft. Measuring 48" x 22" x 14 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $550.32
    Add to Cart
  • 54 Gallon Marine Water Tank MW-504. Technical drawing of a polyethylene water tank designed for marine vessels.

    54 Gallon Marine Water Tank MW-504

    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 54 Gallon Marine Water Tank, Part# MW-504, is engineered to meet the requirements of mobile...

    MSRP: $634.10
    $602.88
    Add to Cart
  • 54 Gallon Marine Water Tank MW-305. Technical drawing of a polyethylene water tank designed for marine vessels.

    54 Gallon Marine Water Tank MW-305

    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 54 Gallon Marine Water Tank, Part# MW-305, is engineered to meet the requirements of mobile...

    MSRP: $502.76
    $478.01
    Add to Cart
  • An image of a 60 Gallon RV Fresh Water Tank | RV54W

    55 Gallon Marine Fresh Water Tank | B528

    This 55-gallon Ronco marine fresh water tank (B528) is built for onboard potable water storage on boats and watercraft. Measuring 34 3/8" x 28 1/2" x 14 5/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $491.07
    Add to Cart
  • An image of a 50 Gallon RV Holding Tank | RV91H

    55 Gallon Marine Fresh Water Tank | B417

    This 55-gallon Ronco marine fresh water tank (B417) is built for onboard potable water storage on boats and watercraft. Measuring 66 1/2" x 31 3/4" x 12 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $667.82
    Add to Cart
  • An image of a 32 Gallon Marine Holding Tank | BOAT2W

    55 Gallon Marine Fresh Water Tank | B351

    This 55-gallon Ronco marine fresh water tank (B351) is built for onboard potable water storage on boats and watercraft. Measuring 40 1/2" x 24 3/4" x 19 3/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $597.52
    Add to Cart
  • 55 Gallon Marine Water Tank MW-479. Technical drawing of a polyethylene water tank designed for marine vessels.

    55 Gallon Marine Water Tank MW-479

    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 55 Gallon Marine Water Tank, Part# MW-479, is engineered to meet the requirements of mobile...

    MSRP: $593.17
    $563.97
    Add to Cart
  • 55 Gallon Marine Water Tank MW-302. Technical drawing of a polyethylene water tank designed for marine vessels.

    55 Gallon Marine Water Tank MW-302

    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 55 Gallon Marine Water Tank, Part# MW-302, is engineered to meet the requirements of mobile...

    MSRP: $451.13
    $428.92
    Add to Cart
  • 56 Gallon Marine Water Tank MW-444. Technical drawing of a polyethylene water tank designed for marine vessels.

    56 Gallon Marine Water Tank MW-444

    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 56 Gallon Marine Water Tank, Part# MW-444, is engineered to meet the requirements of mobile...

    MSRP: $598.44
    $568.97
    Add to Cart
  • 56 Gallon Marine Water Tank MW-360. Technical drawing of a polyethylene water tank designed for marine vessels.

    56 Gallon Marine Water Tank MW-360

    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 56 Gallon Marine Water Tank, Part# MW-360, is engineered to meet the requirements of mobile...

    MSRP: $676.10
    $642.81
    Add to Cart
  • 56 Gallon Marine Water Tank MW-359. Technical drawing of a polyethylene water tank designed for marine vessels.

    56 Gallon Marine Water Tank MW-359

    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 56 Gallon Marine Water Tank, Part# MW-359, is engineered to meet the requirements of mobile...

    MSRP: $676.10
    $642.81
    Add to Cart
  • 56 Gallon Marine Water Tank MW-203. Technical drawing of a polyethylene water tank designed for marine vessels.

    56 Gallon Marine Water Tank MW-203

    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 56 Gallon Marine Water Tank, Part# MW-203, is engineered to meet the requirements of mobile...

    MSRP: $705.28
    $670.56
    Add to Cart
  • 57 Gallon Marine Water Tank MW-467. Technical drawing of a polyethylene water tank designed for marine vessels.

    57 Gallon Marine Water Tank MW-467

    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 57 Gallon Marine Water Tank, Part# MW-467, is engineered to meet the requirements of mobile...

    MSRP: $387.13
    $368.07
    Add to Cart
  • 57 Gallon Marine Water Tank MW-418. Technical drawing of a polyethylene water tank designed for marine vessels.

    57 Gallon Marine Water Tank MW-418

    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 57 Gallon Marine Water Tank, Part# MW-418, is engineered to meet the requirements of mobile...

    MSRP: $620.75
    $590.19
    Add to Cart
  • An image of a 49 Gallon Marine Holding Tank | B482

    58 Gallon Marine Fresh Water Tank | BOAT63W

    This 58-gallon Ronco marine fresh water tank (BOAT63W) is built for onboard potable water storage on boats and watercraft. Measuring 42" x 23" x 15 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $480.02
    Add to Cart
  • An image of a 41 Gallon Marine Holding Tank | B453

    58 Gallon Marine Fresh Water Tank | BOAT60W

    This 58-gallon Ronco marine fresh water tank (BOAT60W) is built for onboard potable water storage on boats and watercraft. Measuring 44" x 22" x 15 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $480.02
    Add to Cart
  • An image of a 25 Gallon RV Fresh Water Tank | RVB250

    58 Gallon Marine Fresh Water Tank | BOAT44W

    This 58-gallon Ronco marine fresh water tank (BOAT44W) is built for onboard potable water storage on boats and watercraft. Measuring 34" x 34" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $480.02
    Add to Cart
  • An image of a 21 Gallon Marine Holding Tank | B396

    58 Gallon Marine Fresh Water Tank | BOAT43W

    This 58-gallon Ronco marine fresh water tank (BOAT43W) is built for onboard potable water storage on boats and watercraft. Measuring 58" x 20" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $515.18
    Add to Cart
  • An image of a 135 Gallon Marine Fresh Water Tank | B407

    58 Gallon Marine Fresh Water Tank | BOAT42W

    This 58-gallon Ronco marine fresh water tank (BOAT42W) is built for onboard potable water storage on boats and watercraft. Measuring 46 3/4" x 20 3/4" x 15 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for...

    $480.02
    Add to Cart
  • 58 Gallon Marine Water Tank MW-486. Technical drawing of a polyethylene water tank designed for marine vessels.

    58 Gallon Marine Water Tank MW-486

    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 58 Gallon Marine Water Tank, Part# MW-486, is engineered to meet the requirements of mobile...

    MSRP: $554.76
    $527.44
    Add to Cart
  • 59 Gallon Marine Water Tank MW-76. Technical drawing of a polyethylene water tank designed for marine vessels.

    59 Gallon Marine Water Tank MW-76

    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 59 Gallon Marine Water Tank, Part# MW-76, is engineered to meet the requirements of mobile...

    MSRP: $448.22
    $426.15
    Add to Cart
  • 59 Gallon Marine Water Tank MW-494. Technical drawing of a polyethylene water tank designed for marine vessels.

    59 Gallon Marine Water Tank MW-494

    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 59 Gallon Marine Water Tank, Part# MW-494, is engineered to meet the requirements of mobile...

    MSRP: $773.73
    $735.64
    Add to Cart
  • An image of a 52 Gallon Marine Fresh Water Tank | BOAT48W

    60 Gallon Marine Fresh Water Tank | BOAT59W

    This 60-gallon Ronco marine fresh water tank (BOAT59W) is built for onboard potable water storage on boats and watercraft. Measuring 40" x 25" x 15 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $480.02
    Add to Cart
  • An image of a 20 Gallon RV Fresh Water Tank | RV72W

    60 Gallon Marine Fresh Water Tank | BOAT54W

    This 60-gallon Ronco marine fresh water tank (BOAT54W) is built for onboard potable water storage on boats and watercraft. Measuring 36 1/4" x 30 1/4" x 14 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for...

    $480.02
    Add to Cart
  • An image of a 33 Gallon Marine Fresh Water Tank | B397

    60 Gallon Marine Fresh Water Tank | B543

    This 60-gallon Ronco marine fresh water tank (B543) is built for onboard potable water storage on boats and watercraft. Measuring 55" x 20" x 14", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $526.22
    Add to Cart
  • An image of a 23 Gallon Marine Holding Tank | BOAT50W

    60 Gallon Marine Fresh Water Tank | B508

    This 60-gallon Ronco marine fresh water tank (B508) is built for onboard potable water storage on boats and watercraft. Measuring 48" x 25" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $526.22
    Add to Cart
  • An image of a 9 Gallon Marine Fresh Water Tank | BOAT23W

    60 Gallon Marine Fresh Water Tank | B474

    This 60-gallon Ronco marine fresh water tank (B474) is built for onboard potable water storage on boats and watercraft. Measuring 30 1/4" x 24 1/2" x 24", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $492.07
    Add to Cart
  • An image of a 30 Gallon RV Fresh Water Tank | RVB350

    60 Gallon Marine Fresh Water Tank | B382

    This 60-gallon Ronco marine fresh water tank (B382) is built for onboard potable water storage on boats and watercraft. Measuring 40" x 42 1/4" x 14 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $573.42
    Add to Cart
  • An image of a 21 Gallon Marine Holding Tank | B490

    60 Gallon Marine Fresh Water Tank | B242

    This 60-gallon Ronco marine fresh water tank (B242) is built for onboard potable water storage on boats and watercraft. Measuring 32" x 23 3/4" x 20 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $526.22
    Add to Cart