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 30 Gallon Marine Holding Tank | B350

    16 Gallon Marine Fresh Water Tank | B109

    This 16-gallon Ronco marine fresh water tank (B109) is built for onboard potable water storage on boats and watercraft. Measuring 21" x 19" x 11 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $246.04
    Add to Cart
  • An image of a 115 Gallon RV Fresh Water Tank | B466

    16 Gallon Marine Fresh Water Tank | B107

    This 16-gallon Ronco marine fresh water tank (B107) is built for onboard potable water storage on boats and watercraft. Measuring 18 1/2" x 23" x 15 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $246.04
    Add to Cart
  • An image of a 14 Gallon Marine Holding Tank | B238

    16 Gallon Marine Fresh Water Tank | B106

    This 16-gallon Ronco marine fresh water tank (B106) is built for onboard potable water storage on boats and watercraft. Measuring 16" x 16" x 16", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $232.98
    Add to Cart
  • 16 Gallon Marine Water Tank MW-559. Technical drawing of a polyethylene water tank designed for marine vessels.

    16 Gallon Marine Water Tank MW-559

    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 16 Gallon Marine Water Tank, Part# MW-559, is engineered to meet the requirements of mobile...

    MSRP: $232.17
    $220.74
    Add to Cart
  • 16 Gallon Marine Water Tank MW-551. Technical drawing of a polyethylene water tank designed for marine vessels.

    16 Gallon Marine Water Tank MW-551

    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 16 Gallon Marine Water Tank, Part# MW-551, is engineered to meet the requirements of mobile...

    MSRP: $258.66
    $245.92
    Add to Cart
  • 16 Gallon Marine Water Tank MW-492. Technical drawing of a polyethylene water tank designed for marine vessels.

    16 Gallon Marine Water Tank MW-492

    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 16 Gallon Marine Water Tank, Part# MW-492, is engineered to meet the requirements of mobile...

    MSRP: $223.33
    $212.33
    Add to Cart
  • 16 Gallon Marine Water Tank MW-27. Technical drawing of a polyethylene water tank designed for marine vessels.

    16 Gallon Marine Water Tank MW-27

    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 16 Gallon Marine Water Tank, Part# MW-27, is engineered to meet the requirements of mobile...

    MSRP: $192.82
    $183.33
    Add to Cart
  • An image of a 138 Gallon PE Ronco White Rectangular Open Top Tank | 40X18X48PE

    17 Gallon Marine Fresh Water Tank | BOAT27W

    This 17-gallon Ronco marine fresh water tank (BOAT27W) is built for onboard potable water storage on boats and watercraft. Measuring 32" x 12" 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
  • An image of a 40 Gallon Marine Holding Tank | B222

    17 Gallon Marine Fresh Water Tank | BOAT20W

    This 17-gallon Ronco marine fresh water tank (BOAT20W) is built for onboard potable water storage on boats and watercraft. Measuring 38" x 15 1/2" x 8 1/8", 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 65 Gallon Marine Holding Tank | B297

    17 Gallon Marine Fresh Water Tank | B462

    This 17-gallon Ronco marine fresh water tank (B462) is built for onboard potable water storage on boats and watercraft. Measuring 37 1/4" x 17 3/4" x 17 1/4", 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 20 Gallon Marine Fresh Water Tank | B231

    17 Gallon Marine Fresh Water Tank | B359

    This 17-gallon Ronco marine fresh water tank (B359) is built for onboard potable water storage on boats and watercraft. Measuring 19 3/4" x 15 3/4" x 14", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $256.08
    Add to Cart
  • An image of a 40 Gallon Marine Holding Tank | B305

    17 Gallon Marine Fresh Water Tank | B325

    This 17-gallon Ronco marine fresh water tank (B325) is built for onboard potable water storage on boats and watercraft. Measuring 19 1/2" x 18" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $256.08
    Add to Cart
  • An image of a 10 Gallon Marine Fresh Water Tank | B278

    17 Gallon Marine Fresh Water Tank | B226

    This 17-gallon Ronco marine fresh water tank (B226) is built for onboard potable water storage on boats and watercraft. Measuring 20 1/8" x 17" x 13 7/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $246.04
    Add to Cart
  • An image of a 30 Gallon Marine Fresh Water Tank | B202

    17 Gallon Marine Fresh Water Tank | B123

    This 17-gallon Ronco marine fresh water tank (B123) is built for onboard potable water storage on boats and watercraft. Measuring 30" x 15" x 13 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $268.13
    Add to Cart
  • An image of a 20 Gallon Marine Fresh Water Tank | B187

    18 Gallon Marine Fresh Water Tank | B527

    This 18-gallon Ronco marine fresh water tank (B527) is built for onboard potable water storage on boats and watercraft. Measuring 34 3/8" x 14 5/8" x 9 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $326.38
    Add to Cart
  • An image of a 45 Gallon Marine Fresh Water Tank | B370

    18 Gallon Marine Fresh Water Tank | B504

    This 18-gallon Ronco marine fresh water tank (B504) is built for onboard potable water storage on boats and watercraft. Measuring 36" x 19 7/8" x 9", 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 35 Gallon Marine Holding Tank | BOAT1W

    18 Gallon Marine Fresh Water Tank | B486

    This 18-gallon Ronco marine fresh water tank (B486) is built for onboard potable water storage on boats and watercraft. Measuring 32" x 24 1/2" x 17 5/8", 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 40 Gallon Marine Holding Tank | B150

    18 Gallon Marine Fresh Water Tank | B412

    This 18-gallon Ronco marine fresh water tank (B412) is built for onboard potable water storage on boats and watercraft. Measuring 41 1/2" x 13 3/4" x 11 1/2", 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 43 Gallon PE Ronco White Rectangular Open Top Tank | 30X12X30PE

    18 Gallon Marine Fresh Water Tank | B369

    This 18-gallon Ronco marine fresh water tank (B369) is built for onboard potable water storage on boats and watercraft. Measuring 47 1/2" x 11 3/8" x 8 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 8 Gallon Marine Holding Tank | B280

    18 Gallon Marine Fresh Water Tank | B366

    This 18-gallon Ronco marine fresh water tank (B366) is built for onboard potable water storage on boats and watercraft. Measuring 22" x 17" x 12", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $268.13
    Add to Cart
  • An image of a 6 Gallon Marine Holding Tank | B357

    18 Gallon Marine Fresh Water Tank | B352

    This 18-gallon Ronco marine fresh water tank (B352) is built for onboard potable water storage on boats and watercraft. Measuring 26 1/2" x 19 1/4" x 11", 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 45 Gallon Marine Holding Tank | B370

    18 Gallon Marine Fresh Water Tank | B345

    This 18-gallon Ronco marine fresh water tank (B345) is built for onboard potable water storage on boats and watercraft. Measuring 25" x 19 7/8" x 18 1/8", 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 12 Gallon Marine Holding Tank | B124

    18 Gallon Marine Fresh Water Tank | B294

    This 18-gallon Ronco marine fresh water tank (B294) is built for onboard potable water storage on boats and watercraft. Measuring 34" x 13" x 14 3/4", 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 48 Gallon Marine Fresh Water Tank | B306

    18 Gallon Marine Fresh Water Tank | B235

    This 18-gallon Ronco marine fresh water tank (B235) is built for onboard potable water storage on boats and watercraft. Measuring 40" x 18" x 6", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $268.13
    Add to Cart
  • An image of a 27 Gallon PE Ronco White Rectangular Open Top Tank | 24X24X12PE

    18 Gallon Marine Fresh Water Tank | B232

    This 18-gallon Ronco marine fresh water tank (B232) is built for onboard potable water storage on boats and watercraft. Measuring 48 1/2" x 10 3/4" x 8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $268.13
    Add to Cart
  • An image of a 20 Gallon Marine Holding Tank | B227

    18 Gallon Marine Fresh Water Tank | B214

    This 18-gallon Ronco marine fresh water tank (B214) is built for onboard potable water storage on boats and watercraft. Measuring 41 1/2" x 15 5/8" x 11 5/8", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $304.28
    Add to Cart
  • An image of a 35 Gallon Marine Fresh Water Tank | B203

    18 Gallon Marine Fresh Water Tank | B212

    This 18-gallon Ronco marine fresh water tank (B212) is built for onboard potable water storage on boats and watercraft. Measuring 41 1/2" x 15" x 11 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $315.32
    Add to Cart
  • An image of a 12 Gallon Marine Fresh Water Tank | BOAT3W

    18 Gallon Marine Fresh Water Tank | B211

    This 18-gallon Ronco marine fresh water tank (B211) is built for onboard potable water storage on boats and watercraft. Measuring 25" x 25" x 7 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $268.13
    Add to Cart
  • An image of a 95 Gallon Marine Holding Tank | B259

    18 Gallon Marine Fresh Water Tank | B192

    This 18-gallon Ronco marine fresh water tank (B192) is built for onboard potable water storage on boats and watercraft. Measuring 33 3/4" x 16 1/2" x 13 1/2", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended...

    $304.28
    Add to Cart
  • An image of a 22 Gallon Marine Fresh Water Tank | B149

    18 Gallon Marine Fresh Water Tank | B167

    This 18-gallon Ronco marine fresh water tank (B167) is built for onboard potable water storage on boats and watercraft. Measuring 27 1/2" x 13 3/4" x 13 1/2", 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 28 Gallon Marine Fresh Water Tank | B239

    18 Gallon Marine Fresh Water Tank | B166

    This 18-gallon Ronco marine fresh water tank (B166) is built for onboard potable water storage on boats and watercraft. Measuring 40" x 16" x 11", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $327.38
    Add to Cart
  • An image of a 8 Gallon Marine Fresh Water Tank | B280

    18 Gallon Marine Fresh Water Tank | B159

    This 18-gallon Ronco marine fresh water tank (B159) is built for onboard potable water storage on boats and watercraft. Measuring 20" x 17" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $256.08
    Add to Cart