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 38 Gallon Marine Holding Tank | B362

    11 Gallon Marine Fresh Water Tank | B319

    This 11-gallon Ronco marine fresh water tank (B319) is built for onboard potable water storage on boats and watercraft. Measuring 35" x 19 1/2" x 4 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $209.88
    Add to Cart
  • An image of a 13 Gallon Marine Fresh Water Tank | B144

    11 Gallon Marine Fresh Water Tank | B286

    This 11-gallon Ronco marine fresh water tank (B286) is built for onboard potable water storage on boats and watercraft. Measuring 15 3/8" x 13 1/2" x 13 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $197.83
    Add to Cart
  • 11 Gallon Marine Water Tank MW-521. Technical drawing of a polyethylene water tank designed for marine vessels.

    11 Gallon Marine Water Tank MW-521

    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 11 Gallon Marine Water Tank, Part# MW-521, is engineered to meet the requirements of mobile...

    MSRP: $166.86
    $158.64
    Add to Cart
  • 11 Gallon Marine Water Tank MW-491. Technical drawing of a polyethylene water tank designed for marine vessels.

    11 Gallon Marine Water Tank MW-491

    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 11 Gallon Marine Water Tank, Part# MW-491, is engineered to meet the requirements of mobile...

    MSRP: $133.05
    $126.50
    Add to Cart
  • 11 Gallon Marine Water Tank MW-210. Technical drawing of a polyethylene water tank designed for marine vessels.

    11 Gallon Marine Water Tank MW-210

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

    MSRP: $191.89
    $182.44
    Add to Cart
  • An image of a 70 Gallon Marine Fresh Water Tank | B153

    12 Gallon Marine Fresh Water Tank | BOAT3W

    This 12-gallon Ronco marine fresh water tank (BOAT3W) is built for onboard potable water storage on boats and watercraft. Measuring 29 3/4" x 13 7/8" x 8 1/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $233.99
    Add to Cart
  • An image of a 20 Gallon Marine Holding Tank | B146

    12 Gallon Marine Fresh Water Tank | B548

    This 12-gallon Ronco marine fresh water tank (B548) is built for onboard potable water storage on boats and watercraft. Measuring 24" x 13 1/2" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $232.98
    Add to Cart
  • An image of a 5 Gallon RV Fresh Water Tank | RVB390

    12 Gallon Marine Fresh Water Tank | B441

    This 12-gallon Ronco marine fresh water tank (B441) is built for onboard potable water storage on boats and watercraft. Measuring 14 3/4" x 14 3/4" x 14 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $232.98
    Add to Cart
  • An image of a 77 Gallon PP Ronco White Rectangular Open Top Tank | 30x18x36PP

    12 Gallon Marine Fresh Water Tank | B279

    This 12-gallon Ronco marine fresh water tank (B279) is built for onboard potable water storage on boats and watercraft. Measuring 23" x 11 1/2" x 11 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $232.98
    Add to Cart
  • An image of a 28 Gallon Marine Fresh Water Tank | B273

    12 Gallon Marine Fresh Water Tank | B255

    This 12-gallon Ronco marine fresh water tank (B255) is built for onboard potable water storage on boats and watercraft. Measuring 17" x 17" x 11", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $232.98
    Add to Cart
  • An image of a 70 Gallon Marine Fresh Water Tank | B296

    12 Gallon Marine Fresh Water Tank | B199

    This 12-gallon Ronco marine fresh water tank (B199) is built for onboard potable water storage on boats and watercraft. Measuring 23 1/2" x 17 5/8" x 9 7/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $281.18
    Add to Cart
  • An image of a 103 Gallon PP Ronco White Rectangular Open Top Tank | 36X24X30PP

    12 Gallon Marine Fresh Water Tank | B124

    This 12-gallon Ronco marine fresh water tank (B124) is built for onboard potable water storage on boats and watercraft. Measuring 20" x 12" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $232.98
    Add to Cart
  • An image of a 14 Gallon Marine Holding Tank | B160

    12 Gallon Marine Fresh Water Tank | B105

    This 12-gallon Ronco marine fresh water tank (B105) is built for onboard potable water storage on boats and watercraft. Measuring 17 1/2" x 14" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $232.98
    Add to Cart
  • 12 Gallon Marine Water Tank ML-2. Technical drawing of a polyethylene water tank designed for marine vessels.

    12 Gallon Marine Water Tank ML-2

    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 12 Gallon Marine Water Tank, Part# ML-2, is engineered to meet the requirements of mobile...

    MSRP: $195.03
    $185.43
    Add to Cart
  • An image of a 20 Gallon Marine Fresh Water Tank | B236

    13 Gallon Marine Fresh Water Tank | BOAT37W

    This 13-gallon Ronco marine fresh water tank (BOAT37W) is built for onboard potable water storage on boats and watercraft. Measuring 29 3/4" x 16" x 7 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $233.99
    Add to Cart
  • An image of a 210 Gallon RV Fresh Water Tank | B302

    13 Gallon Marine Fresh Water Tank | B476

    This 13-gallon Ronco marine fresh water tank (B476) is built for onboard potable water storage on boats and watercraft. Measuring 23" x 18" x 15 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $269.13
    Add to Cart
  • An image of a 11 Gallon PP Ronco White Rectangular Open Top Tank | 24X4X30PP

    13 Gallon Marine Fresh Water Tank | B436

    This 13-gallon Ronco marine fresh water tank (B436) is built for onboard potable water storage on boats and watercraft. Measuring 36 1/2" x 11" x 10", 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 7 Gallon Marine Holding Tank | B275

    13 Gallon Marine Fresh Water Tank | B419

    This 13-gallon Ronco marine fresh water tank (B419) is built for onboard potable water storage on boats and watercraft. Measuring 36 1/2" x 17" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $362.53
    Add to Cart
  • An image of a 30 Gallon Marine Holding Tank | B179

    13 Gallon Marine Fresh Water Tank | B266

    This 13-gallon Ronco marine fresh water tank (B266) is built for onboard potable water storage on boats and watercraft. Measuring 18 1/4" x 14 3/8" x 13 1/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $232.98
    Add to Cart
  • An image of a 16 Gallon Marine Holding Tank | B215

    13 Gallon Marine Fresh Water Tank | B262

    This 13-gallon Ronco marine fresh water tank (B262) is built for onboard potable water storage on boats and watercraft. Measuring 15 7/8" x 15 1/8" x 14 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $232.98
    Add to Cart
  • An image of a 34 Gallon PP Ronco White Rectangular Open Top Tank | 24X12X30PP

    13 Gallon Marine Fresh Water Tank | B218

    This 13-gallon Ronco marine fresh water tank (B218) is built for onboard potable water storage on boats and watercraft. Measuring 48" x 10" x 9", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $269.13
    Add to Cart
  • An image of a 20 Gallon Marine Holding Tank | B291

    13 Gallon Marine Fresh Water Tank | B144

    This 13-gallon Ronco marine fresh water tank (B144) is built for onboard potable water storage on boats and watercraft. Measuring 20 1/8" x 17 1/4" x 9 3/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $269.13
    Add to Cart
  • An image of a 26 Gallon Marine Fresh Water Tank | B406

    13 Gallon Marine Fresh Water Tank | B102

    This 13-gallon Ronco marine fresh water tank (B102) is built for onboard potable water storage on boats and watercraft. Measuring 27" x 20 3/4" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $269.13
    Add to Cart
  • 13 Gallon Marine Water Tank MW-28. Technical drawing of a polyethylene water tank designed for marine vessels.

    13 Gallon Marine Water Tank MW-28

    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 13 Gallon Marine Water Tank, Part# MW-28, is engineered to meet the requirements of mobile...

    MSRP: $219.64
    $208.82
    Add to Cart
  • An image of a 48 Gallon Marine Fresh Water Tank | B229

    14 Gallon Marine Fresh Water Tank | B534

    This 14-gallon Ronco marine fresh water tank (B534) is built for onboard potable water storage on boats and watercraft. Measuring 16 1/5" x 15 3/4" x 14", 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 Fresh Water Tank | B225

    14 Gallon Marine Fresh Water Tank | B274

    This 14-gallon Ronco marine fresh water tank (B274) is built for onboard potable water storage on boats and watercraft. Measuring 15 5/8" x 15 5/8" x 15 1/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $232.98
    Add to Cart
  • An image of a 42 Gallon Marine Fresh Water Tank | B182

    14 Gallon Marine Fresh Water Tank | B265

    This 14-gallon Ronco marine fresh water tank (B265) is built for onboard potable water storage on boats and watercraft. Measuring 17 1/2" x 14 1/2" x 14 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $232.98
    Add to Cart
  • An image of a 20 Gallon Marine Fresh Water Tank | B257

    14 Gallon Marine Fresh Water Tank | B245

    This 14-gallon Ronco marine fresh water tank (B245) is built for onboard potable water storage on boats and watercraft. Measuring 24 1/2" x 16 1/2" x 9 1/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $232.98
    Add to Cart
  • An image of a 42 Gallon Marine Holding Tank | B182

    14 Gallon Marine Fresh Water Tank | B238

    This 14-gallon Ronco marine fresh water tank (B238) is built for onboard potable water storage on boats and watercraft. Measuring 19 1/2" x 14 1/2" x 14 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 150 Gallon Marine Fresh Water Tank | B411

    14 Gallon Marine Fresh Water Tank | B160

    This 14-gallon Ronco marine fresh water tank (B160) is built for onboard potable water storage on boats and watercraft. Measuring 27 1/2" x 21" x 15 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $281.18
    Add to Cart
  • 14 Gallon Marine Water Tank MW-545. Technical drawing of a polyethylene water tank designed for marine vessels.

    14 Gallon Marine Water Tank MW-545

    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 14 Gallon Marine Water Tank, Part# MW-545, is engineered to meet the requirements of mobile...

    MSRP: $444.59
    $422.70
    Add to Cart