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 105 Gallon PE Ronco White Rectangular Open Top Tank | 46X32X18PE

    18 Gallon Marine Fresh Water Tank | B129

    This 18-gallon Ronco marine fresh water tank (B129) is built for onboard potable water storage on boats and watercraft. Measuring 40 1/2" x 12" x 13 3/4", 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 17 Gallon Marine Fresh Water Tank | B123

    18 Gallon Marine Fresh Water Tank | B108

    This 18-gallon Ronco marine fresh water tank (B108) is built for onboard potable water storage on boats and watercraft. Measuring 33" x 13" x 14", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $281.18
    Add to Cart
  • An image of a 17 Gallon Marine Holding Tank | B123

    18 Gallon Marine Fresh Water Tank | B104

    This 18-gallon Ronco marine fresh water tank (B104) is built for onboard potable water storage on boats and watercraft. Measuring 33" x 13" x 12 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on...

    $305.28
    Add to Cart
  • 18 Gallon Marine Water Tank MW-502. Technical drawing of a polyethylene water tank designed for marine vessels.

    18 Gallon Marine Water Tank MW-502

    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 18 Gallon Marine Water Tank, Part# MW-502, is engineered to meet the requirements of mobile...

    MSRP: $346.06
    $329.02
    Add to Cart
  • 18 Gallon Marine Water Tank MW-410. Technical drawing of a polyethylene water tank designed for marine vessels.

    18 Gallon Marine Water Tank MW-410

    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 18 Gallon Marine Water Tank, Part# MW-410, is engineered to meet the requirements of mobile...

    MSRP: $213.12
    $202.63
    Add to Cart
  • 18 Gallon Marine Water Tank MW-361. Technical drawing of a polyethylene water tank designed for marine vessels.

    18 Gallon Marine Water Tank MW-361

    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 18 Gallon Marine Water Tank, Part# MW-361, is engineered to meet the requirements of mobile...

    MSRP: $214.80
    $204.23
    Add to Cart
  • 18 Gallon Marine Water Tank MW-209. Technical drawing of a polyethylene water tank designed for marine vessels.

    18 Gallon Marine Water Tank MW-209

    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 18 Gallon Marine Water Tank, Part# MW-209, is engineered to meet the requirements of mobile...

    MSRP: $265.41
    $252.34
    Add to Cart
  • An image of a 55 Gallon Marine Holding Tank | B351

    19 Gallon Marine Fresh Water Tank | BOAT72W

    This 19-gallon Ronco marine fresh water tank (BOAT72W) is built for onboard potable water storage on boats and watercraft. Measuring 35" x 19" x 7 3/4", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $269.13
    Add to Cart
  • An image of a 45 Gallon Marine Fresh Water Tank | B216

    19 Gallon Marine Fresh Water Tank | B549

    This 19-gallon Ronco marine fresh water tank (B549) is built for onboard potable water storage on boats and watercraft. Measuring 27" x 15 1/4" x 12", 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 16 Gallon Marine Holding Tank | B125

    19 Gallon Marine Fresh Water Tank | B501

    This 19-gallon Ronco marine fresh water tank (B501) is built for onboard potable water storage on boats and watercraft. Measuring 38 1/4" x 13" x 11 1/2", 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 130 Gallon Marine Fresh Water Tank | B467

    19 Gallon Marine Fresh Water Tank | B480

    This 19-gallon Ronco marine fresh water tank (B480) is built for onboard potable water storage on boats and watercraft. Measuring 29" x 23" x 8", 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 39 Gallon PE Ronco White Rectangular Open Top Tank | 18X18X30PE

    19 Gallon Marine Fresh Water Tank | B451

    This 19-gallon Ronco marine fresh water tank (B451) is built for onboard potable water storage on boats and watercraft. Measuring 58 3/4" x 9 3/4" x 11 1/4", 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 20 Gallon PP Ronco White Rectangular Open Top Tank | 18X12X24PP

    19 Gallon Marine Fresh Water Tank | B447

    This 19-gallon Ronco marine fresh water tank (B447) is built for onboard potable water storage on boats and watercraft. Measuring 38" x 9 1/4" x 15", 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 50 Gallon Marine Holding Tank | B308

    19 Gallon Marine Fresh Water Tank | B183

    This 19-gallon Ronco marine fresh water tank (B183) is built for onboard potable water storage on boats and watercraft. Measuring 25" x 18" x 13", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $304.28
    Add to Cart
  • An image of a 95 Gallon RV Fresh Water Tank | B259

    20 Gallon Marine Fresh Water Tank | BOAT57W

    This 20-gallon Ronco marine fresh water tank (BOAT57W) is built for onboard potable water storage on boats and watercraft. Measuring 32" x 16 1/2" x 10", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips...

    $269.13
    Add to Cart
  • An image of a 22 Gallon Marine Holding Tank | B128

    20 Gallon Marine Fresh Water Tank | BOAT39W

    This 20-gallon Ronco marine fresh water tank (BOAT39W) is built for onboard potable water storage on boats and watercraft. Measuring 35" x 13" x 11", 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 58 Gallon Marine Holding Tank | BOAT42W

    20 Gallon Marine Fresh Water Tank | B556

    This 20-gallon Ronco marine fresh water tank (B556) is built for onboard potable water storage on boats and watercraft. Measuring 26" x 25" x 8", 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 20 Gallon Marine Fresh Water Tank | B103

    20 Gallon Marine Fresh Water Tank | B461

    This 20-gallon Ronco marine fresh water tank (B461) is built for onboard potable water storage on boats and watercraft. Measuring 48" x 12 1/2" x 11", 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 53 Gallon Marine Fresh Water Tank | B312

    20 Gallon Marine Fresh Water Tank | B349

    This 20-gallon Ronco marine fresh water tank (B349) is built for onboard potable water storage on boats and watercraft. Measuring 34" x 18" 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 53 Gallon Marine Holding Tank | B312

    20 Gallon Marine Fresh Water Tank | B291

    This 20-gallon Ronco marine fresh water tank (B291) is built for onboard potable water storage on boats and watercraft. Measuring 19" x 18" x 18", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $315.32
    Add to Cart
  • An image of a 30 Gallon RV Fresh Water Tank | RVB424

    20 Gallon Marine Fresh Water Tank | B257

    This 20-gallon Ronco marine fresh water tank (B257) is built for onboard potable water storage on boats and watercraft. Measuring 18 1/2" x 18" x 16", 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 38 Gallon Marine Fresh Water Tank | B311

    20 Gallon Marine Fresh Water Tank | B253

    This 20-gallon Ronco marine fresh water tank (B253) is built for onboard potable water storage on boats and watercraft. Measuring 24" x 18" x 15", it fits a wide range of vessel layouts and provides reliable fresh water capacity for extended trips on the...

    $304.28
    Add to Cart
  • An image of a 90 Gallon Marine Fresh Water Tank | B204

    20 Gallon Marine Fresh Water Tank | B236

    This 20-gallon Ronco marine fresh water tank (B236) is built for onboard potable water storage on boats and watercraft. Measuring 35" x 15" x 14", 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 65 Gallon Marine Fresh Water Tank | B289

    20 Gallon Marine Fresh Water Tank | B234

    This 20-gallon Ronco marine fresh water tank (B234) is built for onboard potable water storage on boats and watercraft. Measuring 33 1/4" x 17 1/8" x 8 3/4", 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 44 Gallon Marine Fresh Water Tank | B414

    20 Gallon Marine Fresh Water Tank | B233

    This 20-gallon Ronco marine fresh water tank (B233) is built for onboard potable water storage on boats and watercraft. Measuring 21" x 21" x 11 1/4", 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 25 Gallon Marine Holding Tank | B184

    20 Gallon Marine Fresh Water Tank | B231

    This 20-gallon Ronco marine fresh water tank (B231) is built for onboard potable water storage on boats and watercraft. Measuring 28 1/4" x 14 1/2" x 11 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 65 Gallon RV Fresh Water Tank | B297

    20 Gallon Marine Fresh Water Tank | B227

    This 20-gallon Ronco marine fresh water tank (B227) is built for onboard potable water storage on boats and watercraft. Measuring 20 3/4" x 17 3/4" x 13 3/4", 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 12 Gallon Marine Holding Tank | B255

    20 Gallon Marine Fresh Water Tank | B213

    This 20-gallon Ronco marine fresh water tank (B213) is built for onboard potable water storage on boats and watercraft. Measuring 28" x 16 1/8" x 12 1/4", 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 18 Gallon Marine Holding Tank | B166

    20 Gallon Marine Fresh Water Tank | B205

    This 20-gallon Ronco marine fresh water tank (B205) is built for onboard potable water storage on boats and watercraft. Measuring 47" x 14" x 12", 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 80 Gallon Marine Fresh Water Tank | B282

    20 Gallon Marine Fresh Water Tank | B200

    This 20-gallon Ronco marine fresh water tank (B200) is built for onboard potable water storage on boats and watercraft. Measuring 24" 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 16 Gallon RV Holding Tank | RV7H

    20 Gallon Marine Fresh Water Tank | B196

    This 20-gallon Ronco marine fresh water tank (B196) is built for onboard potable water storage on boats and watercraft. Measuring 35" x 31" x 14", 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 20 Gallon Marine Fresh Water Tank | B165

    20 Gallon Marine Fresh Water Tank | B195

    This 20-gallon Ronco marine fresh water tank (B195) is built for onboard potable water storage on boats and watercraft. Measuring 42" x 14" 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