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

  • An image of a 20 Gallon RV Fresh Water Tank | RVB231

    135 Gallon Marine Fresh Water Tank | B407

    This 135-gallon Ronco marine fresh water tank (B407) is built for onboard potable water storage on boats and watercraft. Measuring 75 1/2" x 33 1/4" x 14", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $876.71
    Add to Cart
  • An image of a 13 Gallon RV Holding Tank | RV46H

    135 Gallon Marine Fresh Water Tank | B300

    This 135-gallon Ronco marine fresh water tank (B300) is built for onboard potable water storage on boats and watercraft. Measuring 76" x 28" x 16", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $876.71
    Add to Cart
  • 135 Gallon Marine Water Tank MW-239. Technical drawing of a polyethylene water tank designed for marine vessels.

    135 Gallon Marine Water Tank MW-239

    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 135 Gallon Marine Water Tank, Part# MW-239, is engineered to meet the requirements of mobile...

    MSRP: $1,226.50
    $1,166.11
    Add to Cart
  • An image of a 14 Gallon RV Fresh Water Tank | RVB265

    141 Gallon Marine Fresh Water Tank | B484

    This 141-gallon Ronco marine fresh water tank (B484) is built for onboard potable water storage on boats and watercraft. Measuring 53" x 35" x 19", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $900.81
    Add to Cart
  • 142 Gallon Marine Water Tank MW-474. Technical drawing of a polyethylene water tank designed for marine vessels.

    142 Gallon Marine Water Tank MW-474

    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 142 Gallon Marine Water Tank, Part# MW-474, is engineered to meet the requirements of mobile...

    MSRP: $870.96
    $828.08
    Add to Cart
  • 142 Gallon Marine Water Tank MW-272. Technical drawing of a polyethylene water tank designed for marine vessels.

    142 Gallon Marine Water Tank MW-272

    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 142 Gallon Marine Water Tank, Part# MW-272, is engineered to meet the requirements of mobile...

    MSRP: $1,167.85
    $1,110.35
    Add to Cart
  • 143 Gallon Marine Water Tank MW-508. Technical drawing of a polyethylene water tank designed for marine vessels.

    143 Gallon Marine Water Tank MW-508

    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 143 Gallon Marine Water Tank, Part# MW-508, is engineered to meet the requirements of mobile...

    MSRP: $934.46
    $888.46
    Add to Cart
  • An image of a 36 Gallon RV Fresh Water Tank | RVB158

    150 Gallon Marine Fresh Water Tank | B494

    This 150-gallon Ronco marine fresh water tank (B494) is built for onboard potable water storage on boats and watercraft. Measuring 40 1/4" x 32 1/2" x 28 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $923.90
    Add to Cart
  • An image of a 43 Gallon RV Fresh Water Tank | RVB368

    150 Gallon Marine Fresh Water Tank | B411

    This 150-gallon Ronco marine fresh water tank (B411) is built for onboard potable water storage on boats and watercraft. Measuring 54" x 48 1/4" x 27", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $1,147.85
    Add to Cart
  • 150 Gallon Marine Water Tank MW-93. Technical drawing of a polyethylene water tank designed for marine vessels.

    150 Gallon Marine Water Tank MW-93

    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 150 Gallon Marine Water Tank, Part# MW-93, is engineered to meet the requirements of mobile...

    MSRP: $1,244.69
    $1,183.42
    Add to Cart
  • 150 Gallon Marine Water Tank MW-108. Technical drawing of a polyethylene water tank designed for marine vessels.

    150 Gallon Marine Water Tank MW-108

    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 150 Gallon Marine Water Tank, Part# MW-108, is engineered to meet the requirements of mobile...

    MSRP: $865.30
    $822.70
    Add to Cart
  • An image of a 24 Gallon Marine Holding Tank | B564

    155 Gallon Marine Fresh Water Tank | B392

    This 155-gallon Ronco marine fresh water tank (B392) is built for onboard potable water storage on boats and watercraft. Measuring 67" x 24" x 24", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $923.90
    Add to Cart
  • 163 Gallon Marine Water Tank MW-345. Technical drawing of a polyethylene water tank designed for marine vessels.

    163 Gallon Marine Water Tank MW-345

    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 163 Gallon Marine Water Tank, Part# MW-345, is engineered to meet the requirements of mobile...

    MSRP: $1,006.95
    $957.39
    Add to Cart
  • An image of a 22 Gallon RV Holding Tank | RV8H

    165 Gallon Marine Fresh Water Tank | B246

    This 165-gallon Ronco marine fresh water tank (B246) is built for onboard potable water storage on boats and watercraft. Measuring 43 5/8" x 31 5/8" x 30 1/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $935.95
    Add to Cart
  • 165 Gallon Marine Water Tank MW-56. Technical drawing of a polyethylene water tank designed for marine vessels.

    165 Gallon Marine Water Tank MW-56

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

    MSRP: $1,253.19
    $1,191.49
    Add to Cart
  • 165 Gallon Marine Water Tank MW-538. Technical drawing of a polyethylene water tank designed for marine vessels.

    165 Gallon Marine Water Tank MW-538

    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 165 Gallon Marine Water Tank, Part# MW-538, is engineered to meet the requirements of mobile...

    MSRP: $1,218.92
    $1,158.90
    Add to Cart
  • 188 Gallon Marine Water Tank MW-501. Technical drawing of a polyethylene water tank designed for marine vessels.

    188 Gallon Marine Water Tank MW-501

    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 188 Gallon Marine Water Tank, Part# MW-501, is engineered to meet the requirements of mobile...

    MSRP: $1,203.23
    $1,143.99
    Add to Cart
  • 188 Gallon Marine Water Tank MW-372. Technical drawing of a polyethylene water tank designed for marine vessels.

    188 Gallon Marine Water Tank MW-372

    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 188 Gallon Marine Water Tank, Part# MW-372, is engineered to meet the requirements of mobile...

    MSRP: $1,184.07
    $1,125.78
    Add to Cart
  • An image of a 40 Gallon RV Holding Tank | RV71H

    190 Gallon Marine Fresh Water Tank | B506

    This 190-gallon Ronco marine fresh water tank (B506) is built for onboard potable water storage on boats and watercraft. Measuring 56" x 30" x 28", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $1,017.30
    Add to Cart
  • An image of a 40 Gallon RV Fresh Water Tank | RVB256

    200 Gallon Marine Fresh Water Tank | B485

    This 200-gallon Ronco marine fresh water tank (B485) is built for onboard potable water storage on boats and watercraft. Measuring 42" x 34 1/4" x 34 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $1,052.44
    Add to Cart
  • An image of a 7 Gallon RV Fresh Water Tank | RVB287

    210 Gallon Marine Fresh Water Tank | B302

    This 210-gallon Ronco marine fresh water tank (B302) is built for onboard potable water storage on boats and watercraft. Measuring 60" x 36" x 24", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $1,052.44
    Add to Cart
  • 210 Gallon Marine Water Tank MW-548. Technical drawing of a polyethylene water tank designed for marine vessels.

    210 Gallon Marine Water Tank MW-548

    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 210 Gallon Marine Water Tank, Part# MW-548, is engineered to meet the requirements of mobile...

    MSRP: $1,357.12
    $1,290.31
    Add to Cart
  • 220 Gallon Marine Water Tank MW-556. Technical drawing of a polyethylene water tank designed for marine vessels.

    220 Gallon Marine Water Tank MW-556

    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 220 Gallon Marine Water Tank, Part# MW-556, is engineered to meet the requirements of mobile...

    MSRP: $2,044.70
    $1,944.04
    Add to Cart
  • An image of a 5 Gallon RV Fresh Water Tank | RVB377

    260 Gallon Marine Fresh Water Tank | B284

    This 260-gallon Ronco marine fresh water tank (B284) is built for onboard potable water storage on boats and watercraft. Measuring 61 1/4" x 59" x 18", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $1,345.68
    Add to Cart
  • An image of a 35 Gallon RV Holding Tank | RV4H

    280 Gallon Marine Fresh Water Tank | B435

    This 280-gallon Ronco marine fresh water tank (B435) is built for onboard potable water storage on boats and watercraft. Measuring 78" x 28" x 38", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $1,439.09
    Add to Cart
  • 300 Gallon Marine Water Tank MW-476. Technical drawing of a polyethylene water tank designed for marine vessels.

    300 Gallon Marine Water Tank MW-476

    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 300 Gallon Marine Water Tank, Part# MW-476, is engineered to meet the requirements of mobile...

    MSRP: $1,512.04
    $1,437.60
    Add to Cart
  • 375 Gallon Marine Water Tank MW-475. Technical drawing of a polyethylene water tank designed for marine vessels.

    375 Gallon Marine Water Tank MW-475

    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 375 Gallon Marine Water Tank, Part# MW-475, is engineered to meet the requirements of mobile...

    MSRP: $1,621.47
    $1,541.64
    Add to Cart