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

  • 40 Gallon Marine Water Tank MW-205. Technical drawing of a polyethylene water tank designed for marine vessels.

    40 Gallon Marine Water Tank MW-205

    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 40 Gallon Marine Water Tank, Part# MW-205, is engineered to meet the requirements of mobile...

    MSRP: $438.05
    $416.49
    Add to Cart
  • 40 Gallon Marine Water Tank MW-1. Technical drawing of a polyethylene water tank designed for marine vessels.

    40 Gallon Marine Water Tank MW-1

    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 40 Gallon Marine Water Tank, Part# MW-1, is engineered to meet the requirements of mobile...

    MSRP: $432.92
    $411.61
    Add to Cart
  • An image of a 36 Gallon Marine Holding Tank | B478

    41 Gallon Marine Fresh Water Tank | BOAT47W

    This 41-gallon Ronco marine fresh water tank (BOAT47W) is built for onboard potable water storage on boats and watercraft. Measuring 36" x 23" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $421.77
    Add to Cart
  • An image of a 22 Gallon RV Holding Tank | RV10H

    41 Gallon Marine Fresh Water Tank | B453

    This 41-gallon Ronco marine fresh water tank (B453) is built for onboard potable water storage on boats and watercraft. Measuring 22 3/4" x 26 1/2" x 30 7/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $432.83
    Add to Cart
  • 41 Gallon Marine Water Tank MW-515. Technical drawing of a polyethylene water tank designed for marine vessels.

    41 Gallon Marine Water Tank MW-515

    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 41 Gallon Marine Water Tank, Part# MW-515, is engineered to meet the requirements of mobile...

    MSRP: $503.41
    $478.63
    Add to Cart
  • An image of a 69 Gallon Marine Holding Tank | B444

    42 Gallon Marine Fresh Water Tank | B510

    This 42-gallon Ronco marine fresh water tank (B510) is built for onboard potable water storage on boats and watercraft. Measuring 24" x 22" x 20", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $431.82
    Add to Cart
  • An image of a 29 Gallon Marine Fresh Water Tank | B505

    42 Gallon Marine Fresh Water Tank | B443

    This 42-gallon Ronco marine fresh water tank (B443) is built for onboard potable water storage on boats and watercraft. Measuring 24" x 24" x 19", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $408.72
    Add to Cart
  • An image of a 33 Gallon RV Holding Tank | RV15H

    42 Gallon Marine Fresh Water Tank | B380

    This 42-gallon Ronco marine fresh water tank (B380) is built for onboard potable water storage on boats and watercraft. Measuring 40" x 26 3/4" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $408.72
    Add to Cart
  • An image of a 41 Gallon Marine Holding Tank | BOAT47W

    42 Gallon Marine Fresh Water Tank | B237

    This 42-gallon Ronco marine fresh water tank (B237) is built for onboard potable water storage on boats and watercraft. Measuring 36" x 25" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $408.72
    Add to Cart
  • An image of a 115 Gallon Marine Fresh Water Tank | B328

    42 Gallon Marine Fresh Water Tank | B182

    This 42-gallon Ronco marine fresh water tank (B182) is built for onboard potable water storage on boats and watercraft. Measuring 46" x 18" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $408.72
    Add to Cart
  • An image of a 115 Gallon Marine Holding Tank | B328

    42 Gallon Marine Fresh Water Tank | B119

    This 42-gallon Ronco marine fresh water tank (B119) is built for onboard potable water storage on boats and watercraft. Measuring 60" x 18" x 14", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $432.83
    Add to Cart
  • 42 Gallon Marine Water Tank MW-464. Technical drawing of a polyethylene water tank designed for marine vessels.

    42 Gallon Marine Water Tank MW-464

    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 42 Gallon Marine Water Tank, Part# MW-464, is engineered to meet the requirements of mobile...

    MSRP: $379.36
    $360.69
    Add to Cart
  • 42 Gallon Marine Water Tank MW-405. Technical drawing of a polyethylene water tank designed for marine vessels.

    42 Gallon Marine Water Tank MW-405

    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 42 Gallon Marine Water Tank, Part# MW-405, is engineered to meet the requirements of mobile...

    MSRP: $618.00
    $587.57
    Add to Cart
  • 42 Gallon Marine Water Tank MW-204. Technical drawing of a polyethylene water tank designed for marine vessels.

    42 Gallon Marine Water Tank MW-204

    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 42 Gallon Marine Water Tank, Part# MW-204, is engineered to meet the requirements of mobile...

    MSRP: $420.97
    $400.25
    Add to Cart
  • An image of a 35 Gallon Marine Holding Tank | B445

    43 Gallon Marine Fresh Water Tank | BOAT22W

    This 43-gallon Ronco marine fresh water tank (BOAT22W) is built for onboard potable water storage on boats and watercraft. Measuring 36" x 22" x 14", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $421.77
    Add to Cart
  • An image of a 15 Gallon Marine Holding Tank | B251

    43 Gallon Marine Fresh Water Tank | B368

    This 43-gallon Ronco marine fresh water tank (B368) is built for onboard potable water storage on boats and watercraft. Measuring 54" x 16" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $443.87
    Add to Cart
  • An image of a 110 Gallon Marine Holding Tank | B391

    43 Gallon Marine Fresh Water Tank | B220

    This 43-gallon Ronco marine fresh water tank (B220) is built for onboard potable water storage on boats and watercraft. Measuring 30" x 20" x 18", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $431.82
    Add to Cart
  • 43 Gallon Marine Water Tank MW-250. Technical drawing of a polyethylene water tank designed for marine vessels.

    43 Gallon Marine Water Tank MW-250

    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 43 Gallon Marine Water Tank, Part# MW-250, is engineered to meet the requirements of mobile...

    MSRP: $354.97
    $337.49
    Add to Cart
  • An image of a 155 Gallon RV Fresh Water Tank | B392

    44 Gallon Marine Fresh Water Tank | BOAT9W

    This 44-gallon Ronco marine fresh water tank (BOAT9W) is built for onboard potable water storage on boats and watercraft. Measuring 48" x 20" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $456.93
    Add to Cart
  • An image of a 75 Gallon RV Fresh Water Tank | RV61W

    44 Gallon Marine Fresh Water Tank | B440

    This 44-gallon Ronco marine fresh water tank (B440) is built for onboard potable water storage on boats and watercraft. Measuring 44" x 30" x 16 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $608.57
    Add to Cart
  • An image of a 5 Gallon RV Fresh Water Tank | RVB268

    44 Gallon Marine Fresh Water Tank | B414

    This 44-gallon Ronco marine fresh water tank (B414) is built for onboard potable water storage on boats and watercraft. Measuring 45 1/4" x 35 1/2" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $608.57
    Add to Cart
  • 44 Gallon Marine Water Tank MW-48. Technical drawing of a polyethylene water tank designed for marine vessels.

    44 Gallon Marine Water Tank MW-48

    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 44 Gallon Marine Water Tank, Part# MW-48, is engineered to meet the requirements of mobile...

    MSRP: $511.58
    $486.39
    Add to Cart
  • 44 Gallon Marine Water Tank MW-485. Technical drawing of a polyethylene water tank designed for marine vessels.

    44 Gallon Marine Water Tank MW-485

    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 44 Gallon Marine Water Tank, Part# MW-485, is engineered to meet the requirements of mobile...

    MSRP: $468.11
    $445.06
    Add to Cart
  • 44 Gallon Marine Water Tank MW-457. Technical drawing of a polyethylene water tank designed for marine vessels.

    44 Gallon Marine Water Tank MW-457

    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 44 Gallon Marine Water Tank, Part# MW-457, is engineered to meet the requirements of mobile...

    MSRP: $421.64
    $400.88
    Add to Cart
  • An image of a 190 Gallon RV Fresh Water Tank | B506

    45 Gallon Marine Fresh Water Tank | B452

    This 45-gallon Ronco marine fresh water tank (B452) is built for onboard potable water storage on boats and watercraft. Measuring 36" x 24" x 17 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
  • An image of a 42 Gallon RV Fresh Water Tank | RVB182

    45 Gallon Marine Fresh Water Tank | B386

    This 45-gallon Ronco marine fresh water tank (B386) is built for onboard potable water storage on boats and watercraft. Measuring 36" x 33" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $443.87
    Add to Cart
  • An image of a 33 Gallon Marine Holding Tank | B479

    45 Gallon Marine Fresh Water Tank | B379

    This 45-gallon Ronco marine fresh water tank (B379) is built for onboard potable water storage on boats and watercraft. Measuring 30" x 23" x 23", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $538.27
    Add to Cart
  • An image of a 24 Gallon Marine Holding Tank | B446

    45 Gallon Marine Fresh Water Tank | B376

    This 45-gallon Ronco marine fresh water tank (B376) is built for onboard potable water storage on boats and watercraft. Measuring 38" x 22" x 14", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $466.97
    Add to Cart
  • An image of a 65 Gallon Marine Holding Tank | B292

    45 Gallon Marine Fresh Water Tank | B370

    This 45-gallon Ronco marine fresh water tank (B370) is built for onboard potable water storage on boats and watercraft. Measuring 47 1/2" x 17 3/8" x 14 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $466.97
    Add to Cart
  • An image of a 21 Gallon Marine Holding Tank | B355

    45 Gallon Marine Fresh Water Tank | B318

    This 45-gallon Ronco marine fresh water tank (B318) is built for onboard potable water storage on boats and watercraft. Measuring 40" x 19" x 15 5/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $443.87
    Add to Cart
  • An image of a 15 Gallon Marine Holding Tank | B173

    45 Gallon Marine Fresh Water Tank | B317

    This 45-gallon Ronco marine fresh water tank (B317) is built for onboard potable water storage on boats and watercraft. Measuring 64 1/2" x 14" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $511.16
    Add to Cart