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

  • 28 Gallon Marine Water Tank MW-513. Technical drawing of a polyethylene water tank designed for marine vessels.

    28 Gallon Marine Water Tank MW-513

    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 28 Gallon Marine Water Tank, Part# MW-513, is engineered to meet the requirements of mobile...

    MSRP: $606.21
    $576.37
    Add to Cart
  • 28 Gallon Marine Water Tank MW-468. Technical drawing of a polyethylene water tank designed for marine vessels.

    28 Gallon Marine Water Tank MW-468

    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 28 Gallon Marine Water Tank, Part# MW-468, is engineered to meet the requirements of mobile...

    MSRP: $382.95
    $364.11
    Add to Cart
  • 28 Gallon Marine Water Tank MW-45. Technical drawing of a polyethylene water tank designed for marine vessels.

    28 Gallon Marine Water Tank MW-45

    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 28 Gallon Marine Water Tank, Part# MW-45, is engineered to meet the requirements of mobile...

    MSRP: $268.84
    $255.60
    Add to Cart
  • 28 Gallon Marine Water Tank MW-260. Technical drawing of a polyethylene water tank designed for marine vessels.

    28 Gallon Marine Water Tank MW-260

    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 28 Gallon Marine Water Tank, Part# MW-260, is engineered to meet the requirements of mobile...

    MSRP: $315.07
    $299.57
    Add to Cart
  • 28 Gallon Marine Water Tank MW-207. Technical drawing of a polyethylene water tank designed for marine vessels.

    28 Gallon Marine Water Tank MW-207

    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 28 Gallon Marine Water Tank, Part# MW-207, is engineered to meet the requirements of mobile...

    MSRP: $294.82
    $280.30
    Add to Cart
  • An image of a 28 Gallon Marine Holding Tank | B437

    29 Gallon Marine Fresh Water Tank | B505

    This 29-gallon Ronco marine fresh water tank (B505) is built for onboard potable water storage on boats and watercraft. Measuring 38" x 22" x 11", 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 24 Gallon Marine Holding Tank | B402

    29 Gallon Marine Fresh Water Tank | B497

    This 29-gallon Ronco marine fresh water tank (B497) is built for onboard potable water storage on boats and watercraft. Measuring 33 3/4" x 20 3/8" x 23", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $350.48
    Add to Cart
  • An image of a 30 Gallon RV Holding Tank | RV22H

    29 Gallon Marine Fresh Water Tank | B423

    This 29-gallon Ronco marine fresh water tank (B423) is built for onboard potable water storage on boats and watercraft. Measuring 57 3/4" x 27" x 10", 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 50 Gallon RV Fresh Water Tank | RVB156

    29 Gallon Marine Fresh Water Tank | B421

    This 29-gallon Ronco marine fresh water tank (B421) is built for onboard potable water storage on boats and watercraft. Measuring 31" x 32 1/4" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $515.18
    Add to Cart
  • 29 Gallon Marine Water Tank MW-465. Technical drawing of a polyethylene water tank designed for marine vessels.

    29 Gallon Marine Water Tank MW-465

    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 29 Gallon Marine Water Tank, Part# MW-465, is engineered to meet the requirements of mobile...

    MSRP: $303.43
    $288.49
    Add to Cart
  • 29 Gallon Marine Water Tank MW-323. Technical drawing of a polyethylene water tank designed for marine vessels.

    29 Gallon Marine Water Tank MW-323

    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 29 Gallon Marine Water Tank, Part# MW-323, is engineered to meet the requirements of mobile...

    MSRP: $284.29
    $270.29
    Add to Cart
  • An image of a 9 Gallon Marine Holding Tank | B321

    30 Gallon Marine Fresh Water Tank | B502

    This 30-gallon Ronco marine fresh water tank (B502) is built for onboard potable water storage on boats and watercraft. Measuring 36 1/4" x 18" x 16", 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 13 Gallon Marine Holding Tank | B218

    30 Gallon Marine Fresh Water Tank | B488

    This 30-gallon Ronco marine fresh water tank (B488) is built for onboard potable water storage on boats and watercraft. Measuring 29 3/4" x 15 1/4" x 19 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 32 Gallon Marine Fresh Water Tank | B353

    30 Gallon Marine Fresh Water Tank | B481

    This 30-gallon Ronco marine fresh water tank (B481) is built for onboard potable water storage on boats and watercraft. Measuring 45 7/8" x 19" x 11 7/8", 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 60 Gallon Marine Holding Tank | BOAT59W

    30 Gallon Marine Fresh Water Tank | B457

    This 30-gallon Ronco marine fresh water tank (B457) is built for onboard potable water storage on boats and watercraft. Measuring 32 1/4" x 25 1/4" x 10 1/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $456.93
    Add to Cart
  • An image of a 48 Gallon Marine Holding Tank | B384

    30 Gallon Marine Fresh Water Tank | B424

    This 30-gallon Ronco marine fresh water tank (B424) is built for onboard potable water storage on boats and watercraft. Measuring 40" x 20" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $326.38
    Add to Cart
  • An image of a 30 Gallon RV Fresh Water Tank | RVB162

    30 Gallon Marine Fresh Water Tank | B418

    This 30-gallon Ronco marine fresh water tank (B418) is built for onboard potable water storage on boats and watercraft. Measuring 47 1/2" x 32 3/4" x 11", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $538.27
    Add to Cart
  • An image of a 58 Gallon Marine Fresh Water Tank | BOAT43W

    30 Gallon Marine Fresh Water Tank | B405

    This 30-gallon Ronco marine fresh water tank (B405) is built for onboard potable water storage on boats and watercraft. Measuring 33" x 25" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $456.93
    Add to Cart
  • An image of a 30 Gallon Marine Holding Tank | B405

    30 Gallon Marine Fresh Water Tank | B350

    This 30-gallon Ronco marine fresh water tank (B350) is built for onboard potable water storage on boats and watercraft. Measuring 33" x 20 1/2" x 11", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $326.38
    Add to Cart
  • An image of a 70 Gallon Marine Holding Tank | B208

    30 Gallon Marine Fresh Water Tank | B228

    This 30-gallon Ronco marine fresh water tank (B228) is built for onboard potable water storage on boats and watercraft. Measuring 69" x 15" x 11", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $397.67
    Add to Cart
  • An image of a 30 Gallon Marine Holding Tank | B189

    30 Gallon Marine Fresh Water Tank | B202

    This 30-gallon Ronco marine fresh water tank (B202) is built for onboard potable water storage on boats and watercraft. Measuring 41 1/4" x 14 5/8" x 20 1/8", 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 40 Gallon Marine Fresh Water Tank | B347

    30 Gallon Marine Fresh Water Tank | B191

    This 30-gallon Ronco marine fresh water tank (B191) is built for onboard potable water storage on boats and watercraft. Measuring 35 3/8" x 18 7/8" x 15 1/4", 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 17 Gallon Marine Fresh Water Tank | B359

    30 Gallon Marine Fresh Water Tank | B190

    This 30-gallon Ronco marine fresh water tank (B190) is built for onboard potable water storage on boats and watercraft. Measuring 34 3/8" x 19 3/8" x 15 7/8", 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 165 Gallon Marine Fresh Water Tank | B246

    30 Gallon Marine Fresh Water Tank | B189

    This 30-gallon Ronco marine fresh water tank (B189) is built for onboard potable water storage on boats and watercraft. Measuring 38" x 16" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $362.53
    Add to Cart
  • An image of a 100 Gallon Marine Holding Tank | B426

    30 Gallon Marine Fresh Water Tank | B179

    This 30-gallon Ronco marine fresh water tank (B179) is built for onboard potable water storage on boats and watercraft. Measuring 35 1/2" x 21 1/4" x 13", 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 16 Gallon Marine Holding Tank | B500

    30 Gallon Marine Fresh Water Tank | B162

    This 30-gallon Ronco marine fresh water tank (B162) is built for onboard potable water storage on boats and watercraft. Measuring 30" x 24" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $326.38
    Add to Cart
  • An image of a 48 Gallon Marine Fresh Water Tank | B384

    30 Gallon Marine Fresh Water Tank | B157

    This 30-gallon Ronco marine fresh water tank (B157) is built for onboard potable water storage on boats and watercraft. Measuring 30" x 20" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $326.38
    Add to Cart
  • An image of a 70 Gallon Marine Fresh Water Tank | B208

    30 Gallon Marine Fresh Water Tank | B140

    This 30-gallon Ronco marine fresh water tank (B140) is built for onboard potable water storage on boats and watercraft. Measuring 39" x 15" x 12 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $326.38
    Add to Cart
  • An image of a 35 Gallon Marine Holding Tank | BOAT7W

    30 Gallon Marine Fresh Water Tank | B126

    This 30-gallon Ronco marine fresh water tank (B126) is built for onboard potable water storage on boats and watercraft. Measuring 38" x 26" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $362.53
    Add to Cart
  • An image of a 45 Gallon Marine Holding Tank | B386

    30 Gallon Marine Fresh Water Tank | B118

    This 30-gallon Ronco marine fresh water tank (B118) is built for onboard potable water storage on boats and watercraft. Measuring 24" x 20" x 16", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $326.38
    Add to Cart
  • An image of a 165 Gallon Marine Holding Tank | B246

    30 Gallon Marine Fresh Water Tank | B112

    This 30-gallon Ronco marine fresh water tank (B112) is built for onboard potable water storage on boats and watercraft. Measuring 53" x 16" x 12 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $339.43
    Add to Cart