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Marine Water or Waste Holding Tanks - 26 to 50 Gallons

The Best Marine Water Tanks & Waste Holding Tanks for Boaters
Salt. Spray. Motion. Pressure. Plumbing a boat or marine vehicle isn’t just about finding a tank that fits — it’s about choosing one that can handle life at sea. But those same elements—corrosive salt, relentless UV rays, and the constant pounding stress from waves—are absolutely brutal on your boat's equipment. This is especially true for your holding tanks. A thin, brittle, or poorly-made tank isn't just an inconvenience; it's a ticking time bomb for a catastrophic leak or a smell you can't get rid of....

That’s exactly why these tanks exist. This is our premier line of marine water and waste holding tanks, engineered to pull double duty and built to survive. Whether you need a safe, robust marine water tank for your galley or a bulletproof marine waste holding tank for black water, this is your 'buy it once' solution. Built from heavy-duty, rotationally molded, corrosion-proof polyethylene, these plastic boat tanks with sizes sizes from 3 gallons to 260 gallons are designed to fit your hull, withstand the sea, and give you one less thing to worry about. With blank tank options, pre-installed fittings, and fully customizable configurations, you’re in control of your system — down to the last thread.

Key Applications of Marine Fresh Water & Waste Holding Tanks

These tanks are the foundation of a reliable marine plumbing system, giving you the flexibility to build it right for any application.

Trust Your Water Supply
Trust Your Water Supply

When you're miles from shore, you need a safe source. Our boat water tanks are manufactured from FDA-approved, food-grade, BPA-free resin, ensuring your water is 100% potable, safe, and taste-free.

Built for All Onboard Needs
Built for All Onboard Needs

These tanks are the perfect potable water tank for boat systems. They are built to reliably feed your galley water systems, supply deck rinse stations, and serve as durable potable water reserves on day or offshore boats.

Lock in Odors for Good
Lock in Odors for Good

A boat holding tank for waste cannot fail. Our marine waste tanks feature a seamless, thick wall marine holding tank construction (up to 3/8-inch thick) that is impermeable to waste, permanently locking in odors and preventing leaks.

Meet All Waste Compliance Needs
Meet All Waste Compliance Needs

Engineered as the ultimate marine black water tank, these versatile tanks are also perfect for galley or shower grey water holding. They are designed to meet the rigorous standards of boats requiring Coast Guard-compliant waste systems, giving you total peace of mind.

Why Choose Tank Depot for your Marine Fresh Water Tanks and Marine Waste Holding Tanks

When you're outfitting your vessel, you need two things: a product that can survive the sea and a partner who understands the complexity of a boat. Here’s why we are the top choice for boaters who demand reliability.

Unrivaled Selection
Unmatched Durability

Our tanks are rotationally molded into a single, seamless piece. This process, combined with heavy-duty polyethylene construction (up to 3/8" thick), means there are no weak points to leak, crack, or fail. They are 100% corrosion-proof, won't rust like metal, and are impervious to the stresses of salt, waste, and constant hull vibration.

Installation Flexibility
Installation Flexibility

We know "one-size-fits-all" doesn't work on a boat. Many of our tanks ship "blank," allowing you to drill and place fittings to match your exact plumbing lines. Need something more? Our "Build Your Own Tank" service makes you the designer.

The Right Fit for Your Hull
The Right Fit for Your Hull

Don't compromise on capacity. Our inventory is one of the largest available, with tanks from a compact 3 gallons to a massive 260 gallons.Our marine tanks are designed to maximize storage in the tight, irregular spaces of a hull.

Compliance and Peace of Mind
Compliance and Peace of Mind

Sail with confidence. Our Trionic marine waste holding tanks are built to meet or exceed all U.S. Coast Guard standards, including FDA 177.1520, giving you peace of mind for inspections, pump-outs, and safe operation on the water.

Expert Support
Expert Support

We understand the unique challenges of marine plumbing. Our expert team can review your drawings, help you plan your system, and ensure you get the right tank and the right fittings for your specific build, the first time.

The Complete System in One Stop
The Complete System in One Stop

A tank is just the beginning. We also stock marine and RV tank accessories, including the specific fitting kits, pump-out kits, and gauges you need to complete your installation like a pro.

Start Your System with a Marine Water & Waste Tank That’s Built for the Water — and Built to Last

From the bilge to the bow, every inch of your boat or marine vehicle serves a purpose. Your water and waste systems should be no different. At Tank Depot, we carry a full selection of marine-rated plastic holding tanks designed to make your install smoother, your system safer, and your time on the water cleaner and more reliable.

Whether you're piecing together a full marine sanitation system, upgrading an aging boat water storage tank, or starting fresh with a 50-gallon rectangular marine tank, we've got the right options to match your space, your specs, and your standards.

Not sure what size you need? Want help mapping out your fittings? Our team has helped thousands of boat owners, van lifers, and RV techs build smarter plumbing systems — and we’re here when you’re ready. Browse all options below.
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Capacity Name Diameter Length Width Height SKU Price
Buy 26 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $439.99 26 Gallons Buy 26 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $439.99 Ronco Plastics 26 Gallon Plastic Marine and RV Water or Waste Holding Tank 74 10 9 R-B515 $439.99
Buy 26 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 26 Gallons Buy 26 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 Ronco Plastics 26 Gallon Plastic Marine Water Tank without Fittings 76 12.75 10.5 R-B329 $366.00
Buy 26 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 26 Gallons Buy 26 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 26 Gallon Plastic Marine and RV Water or Waste Holding Tank 60 21 6 R-B406 $379.99
Buy 26 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 26 Gallons Buy 26 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 Ronco Plastics 26 Gallon Plastic Marine Water Tank without Fittings 42 19 11.5 R-B145 $348.00
Buy 26 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 26 Gallons Buy 26 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 Ronco Plastics 26 Gallon Plastic Marine Water Tank without Fittings 30.25 13.25 28 R-B338 $348.00
Buy 26 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 26 Gallons Buy 26 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 Ronco Plastics 26 Gallon Plastic Marine Water Tank without Fittings 20 16.5 23.5 R-B332 $348.00
Buy 27 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 27 Gallons Buy 27 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 Ronco Plastics 27 Gallon Plastic Marine Water Tank without Fittings 42.25 22.25 11.5 R-B342 $366.00
Buy 27 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 27 Gallons Buy 27 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 Ronco Plastics 27 Gallon Plastic Marine Water Tank without Fittings 27 34.875 10 R-B459 $440.00
Buy 27 Gallon Plastic RV or Marine Water or Waste Holding Tank by Ronco Plastics for only $554.00 27 Gallons Buy 27 Gallon Plastic RV or Marine Water or Waste Holding Tank by Ronco Plastics for only $554.00 Ronco Plastics 27 Gallon Plastic RV or Marine Water or Waste Holding Tank 43 16 10.5 R-24W $554.00
Buy 28 Gallon Plastic RV Water Tank by Ronco Plastics for only $369.99 28 Gallons Buy 28 Gallon Plastic RV Water Tank by Ronco Plastics for only $369.99 Ronco Plastics 28 Gallon Plastic RV Water Tank 48 20 8 R-69W $369.99
Buy 28 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 28 Gallons Buy 28 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 28 Gallon Plastic Marine and RV Water or Waste Holding Tank 35.5 15 13 R-B161 $379.99
Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $385.00 28 Gallons Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $385.00 Ronco Plastics 28 Gallon Plastic Marine Water Tank without Fittings 27 24 19 R-B374 $385.00
Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 28 Gallons Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 Ronco Plastics 28 Gallon Plastic Marine Water Tank without Fittings 36 24 14 R-B413 $440.00
Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 28 Gallons Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 Ronco Plastics 28 Gallon Plastic Marine Water Tank without Fittings 39.75 19.75 15.5 R-B415 $440.00
Buy 28 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $399.99 28 Gallons Buy 28 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $399.99 Ronco Plastics 28 Gallon Plastic Marine and RV Water or Waste Holding Tank 48 14 10 R-B239 $399.99
Buy 28 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 28 Gallons Buy 28 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 28 Gallon Plastic Marine and RV Water or Waste Holding Tank 36 18 12 R-B437 $379.99
Buy 28 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $399.99 28 Gallons Buy 28 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $399.99 Ronco Plastics 28 Gallon Plastic Marine and RV Water or Waste Holding Tank 20.75 19.75 17.625 R-B273 $399.99
Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 28 Gallons Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 Ronco Plastics 28 Gallon Plastic Marine Water Tank without Fittings 35 21 14 R-B169 $366.00
Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $385.00 28 Gallons Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $385.00 Ronco Plastics 28 Gallon Plastic Marine Water Tank without Fittings 35.25 11 23.25 R-B206 $385.00
Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 28 Gallons Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 Ronco Plastics 28 Gallon Plastic Marine Water Tank without Fittings 52 11.75 10.75 R-B335 $366.00
Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $403.00 28 Gallons Buy 28 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $403.00 Ronco Plastics 28 Gallon Plastic Marine Water Tank without Fittings 48 18.5 10 R-B394 $403.00
Buy 28 Gallon Plastic RV Water Tank by Ronco Plastics for only $587.00 28 Gallons Buy 28 Gallon Plastic RV Water Tank by Ronco Plastics for only $587.00 Ronco Plastics 28 Gallon Plastic RV Water Tank 60 16 8 R-52W $587.00
Buy 29 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $494.00 29 Gallons Buy 29 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $494.00 Ronco Plastics 29 Gallon Plastic Marine Water Tank without Fittings 57.75 27 10 R-B423 $494.00
Buy 29 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $330.00 29 Gallons Buy 29 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $330.00 Ronco Plastics 29 Gallon Plastic Marine Water Tank without Fittings 38.875 21.5 10.5 R-B505 $330.00
Buy 29 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $330.00 29 Gallons Buy 29 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $330.00 Ronco Plastics 29 Gallon Plastic Marine Water Tank without Fittings 33.75 20.375 23 R-B497 $330.00
Buy 29 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $494.00 29 Gallons Buy 29 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $494.00 Ronco Plastics 29 Gallon Plastic Marine Water Tank without Fittings 30.5 32.25 12 R-B421 $494.00
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 39 15 12.5 R-B140 $379.99
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 24 20 16 R-B118 $379.99
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 40 20 10 R-B424 $379.99
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 33 20.5 11 R-B350 $379.99
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 35.5 21.25 13 R-B179 $348.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $385.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $385.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 68.5 15 10.5 R-B228 $385.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 33 25 9.75 R-B405 $440.00
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 Trionic 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 50 20 7 TRI-2030 As low as$402.50
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 Trionic 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 36.188 14.938 14.5 TRI-2030-5 As low as$402.50
Buy 30 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $348.00 30 Gallons Buy 30 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $348.00 Ronco Plastics 30 Gallon Plastic Marine Water or Waste Holding Tank 38 16 13 R-B189 $348.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $385.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $385.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 41.25 14.625 20.125 R-B202 $385.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $513.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $513.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 47.5 32.75 11 R-B418 $513.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $440.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 32.5 25.25 10.25 R-B457 $440.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $311.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $311.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 45.875 19 11.875 R-B481 $311.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $311.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $311.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 29.75 15.25 19.25 R-B488 $311.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $311.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $311.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 36.25 18 16 R-B502 $311.00
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 Trionic 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 42 26 7 TRI-2030-3 As low as$402.50
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $348.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 38 26 13 R-B126 $348.00
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 30 24 10 R-B162 $379.99
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $379.99 Ronco Plastics 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 30 20 12 R-B157 $379.99
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 34.375 19.375 15 R-B190 $366.00
Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 30 Gallons Buy 30 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $366.00 Ronco Plastics 30 Gallon Plastic Marine Water Tank without Fittings 35.375 18.875 15.25 R-B191 $366.00
Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 30 Gallons Buy 30 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 Trionic 30 Gallon Plastic Marine and RV Water or Waste Holding Tank 46 13 12 TRI-2030-4 As low as$402.50
Buy 31 Gallon Plastic RV or Marine Water or Waste Holding Tank by Ronco Plastics for only $587.00 31 Gallons Buy 31 Gallon Plastic RV or Marine Water or Waste Holding Tank by Ronco Plastics for only $587.00 Ronco Plastics 31 Gallon Plastic RV or Marine Water or Waste Holding Tank 31 23 11.5 R-26W $587.00
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