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Marine Water or Waste Holding Tanks

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 3 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $147.00 3 Gallons Buy 3 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $147.00 Ronco Plastics 3 Gallon Plastic Marine and RV Water or Waste Holding Tank 18.5 9.5 6.75 R-B377 $147.00
Buy 3 Gallon Plastic RV Water Tank by Ronco Plastics for only $109.99 3 Gallons Buy 3 Gallon Plastic RV Water Tank by Ronco Plastics for only $109.99 Ronco Plastics 3 Gallon Plastic RV Water Tank 17 7 7 R-13W $109.99
Buy 3 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $149.99 3 Gallons Buy 3 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $149.99 Ronco Plastics 3 Gallon Plastic Marine and RV Water or Waste Holding Tank 16.375 9 5.25 R-B267 $149.99
Buy 4 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $128.00 4 Gallons Buy 4 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $128.00 Ronco Plastics 4 Gallon Plastic Marine and RV Water or Waste Holding Tank 17.625 8.25 7.875 R-B269 $128.00
Buy 4 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 4 Gallons Buy 4 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 Trionic 4 Gallon Plastic Marine and RV Water or Waste Holding Tank 13.125 10 8 TRI-2004 As low as$140.50
Buy 4.25 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $139.00 4.25 Gallons Buy 4.25 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $139.00 Ronco Plastics 4.25 Gallon Plastic Marine Water or Waste Holding Tank 26 11 7 R-B525 $139.00
Buy 5 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $147.00 5 Gallons Buy 5 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $147.00 Ronco Plastics 5 Gallon Plastic Marine Water Tank without Fittings 24 12 5 R-B303 $147.00
Buy 5 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $179.99 5 Gallons Buy 5 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $179.99 Ronco Plastics 5 Gallon Plastic Marine and RV Water or Waste Holding Tank 20 12 5.5 R-B390 $179.99
Buy 5 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $149.99 5 Gallons Buy 5 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $149.99 Ronco Plastics 5 Gallon Plastic Marine and RV Water or Waste Holding Tank 12.25 12.25 8.25 R-B268 $149.99
Buy 5 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $179.99 5 Gallons Buy 5 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $179.99 Ronco Plastics 5 Gallon Plastic Marine and RV Water or Waste Holding Tank 18 13.5 7 R-B410 $179.99
Buy 5 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $179.99 5 Gallons Buy 5 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $179.99 Ronco Plastics 5 Gallon Plastic Marine Water or Waste Holding Tank 21 8.25 8 R-B322 $179.99
Buy 6 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $165.00 6 Gallons Buy 6 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $165.00 Ronco Plastics 6 Gallon Plastic Marine Water or Waste Holding Tank 21.625 14.625 5.625 R-B285 $165.00
Buy 6 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $199.99 6 Gallons Buy 6 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $199.99 Ronco Plastics 6 Gallon Plastic Marine Water or Waste Holding Tank 20 11.5 7 R-B357 $199.99
Buy 6 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $155.00 6 Gallons Buy 6 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $155.00 Ronco Plastics 6 Gallon Plastic Marine Water or Waste Holding Tank 13.75 13.75 10 R-B404 $155.00
Buy 6 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 6 Gallons Buy 6 Gallon Plastic Marine and RV Water or Waste Holding Tank by Trionic for only $0.00 Trionic 6 Gallon Plastic Marine and RV Water or Waste Holding Tank 16 11.75 8 TRI-2006 As low as$151.00
Buy 6 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $199.99 6 Gallons Buy 6 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $199.99 Ronco Plastics 6 Gallon Plastic Marine and RV Water or Waste Holding Tank 16 12 8 R-B277 $199.99
Buy 6.5 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $239.99 6.5 Gallons Buy 6.5 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $239.99 Ronco Plastics 6.5 Gallon Plastic Marine and RV Water or Waste Holding Tank 27 13.25 4.25 R-B533 $239.99
Buy 7 Gallon Plastic RV Water Tank by Ronco Plastics for only $380.00 7 Gallons Buy 7 Gallon Plastic RV Water Tank by Ronco Plastics for only $380.00 Ronco Plastics 7 Gallon Plastic RV Water Tank 20.5 13.75 8 R-56W $380.00
Buy 7 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $165.00 7 Gallons Buy 7 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $165.00 Ronco Plastics 7 Gallon Plastic Marine Water or Waste Holding Tank 15.625 15.125 7.75 R-B275 $165.00
Buy 7 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $199.99 7 Gallons Buy 7 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $199.99 Ronco Plastics 7 Gallon Plastic Marine and RV Water or Waste Holding Tank 24.25 12.5 5.75 R-B272 $199.99
Buy 7 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $165.00 7 Gallons Buy 7 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $165.00 Ronco Plastics 7 Gallon Plastic Marine and RV Water or Waste Holding Tank 19.25 13.125 7.125 R-B271 $165.00
Buy 7 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $165.00 7 Gallons Buy 7 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $165.00 Ronco Plastics 7 Gallon Plastic Marine Water Tank without Fittings 27 14.375 5 R-B395 $165.00
Buy 7 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $149.99 7 Gallons Buy 7 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $149.99 Ronco Plastics 7 Gallon Plastic Marine and RV Water or Waste Holding Tank 12 12 12 R-B326 $149.99
Buy 7 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $165.00 7 Gallons Buy 7 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $165.00 Ronco Plastics 7 Gallon Plastic Marine Water or Waste Holding Tank 21.5 10 8.75 R-B344 $165.00
Buy 7 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $199.99 7 Gallons Buy 7 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $199.99 Ronco Plastics 7 Gallon Plastic Marine and RV Water or Waste Holding Tank 27 10.25 6.5 R-B287 $199.99
Buy 7.5 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $138.99 7.5 Gallons Buy 7.5 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $138.99 Ronco Plastics 7.5 Gallon Plastic Marine Water or Waste Holding Tank 13 12 12 R-B535 $138.99
Buy 8 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $239.99 8 Gallons Buy 8 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $239.99 Ronco Plastics 8 Gallon Plastic Marine Water Tank without Fittings 18 14.625 10 R-B280 $239.99
Buy 8 Gallon Plastic RV Water Tanks by Ronco Plastics for only $326.00 8 Gallons Buy 8 Gallon Plastic RV Water Tanks by Ronco Plastics for only $326.00 Ronco Plastics 8 Gallon Plastic RV Water Tanks 18 12.75 10 R-41W $326.00
Buy 8 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 8 Gallons Buy 8 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 Ronco Plastics 8 Gallon Plastic Marine and RV Water or Waste Holding Tank 18 11.5 10 R-B186 $219.99
Buy 8 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 8 Gallons Buy 8 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 Ronco Plastics 8 Gallon Plastic Marine and RV Water or Waste Holding Tank 23.5 10 8.5 R-B360 $219.99
Buy 8 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 8 Gallons Buy 8 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 Ronco Plastics 8 Gallon Plastic Marine and RV Water or Waste Holding Tank 24 12.25 6.875 R-B270 $219.99
Buy 8 Gallon RV Fresh or Grey Water Holding Tank by Ronco Plastics for only $326.00 8 Gallons Buy 8 Gallon RV Fresh or Grey Water Holding Tank by Ronco Plastics for only $326.00 Ronco Plastics 8 Gallon RV Fresh or Grey Water Holding Tank 18 15.75 8.25 R-21W $326.00
Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 9 Gallons Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 Ronco Plastics 9 Gallon Plastic Marine and RV Water or Waste Holding Tank 25.5 10.5 8.5 R-B361 $219.99
Buy 9 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $183.00 9 Gallons Buy 9 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $183.00 Ronco Plastics 9 Gallon Plastic Marine Water or Waste Holding Tank 31 10.5 7 R-B341 $183.00
Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 9 Gallons Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 Ronco Plastics 9 Gallon Plastic Marine and RV Water or Waste Holding Tank 19.5 14 8 R-B358 $219.99
Buy 9 Gallon Plastic RV Water Tank by Ronco Plastics for only $199.99 9 Gallons Buy 9 Gallon Plastic RV Water Tank by Ronco Plastics for only $199.99 Ronco Plastics 9 Gallon Plastic RV Water Tank 30.25 10 9 R-23W $199.99
Buy 9 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $219.99 9 Gallons Buy 9 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $219.99 Ronco Plastics 9 Gallon Plastic Marine Water or Waste Holding Tank 18 12.5 11 R-B321 $219.99
Buy 9 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $173.00 9 Gallons Buy 9 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $173.00 Ronco Plastics 9 Gallon Plastic Marine Water or Waste Holding Tank 18.75 17 7.5 R-B532 $173.00
Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $239.99 9 Gallons Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $239.99 Ronco Plastics 9 Gallon Plastic Marine and RV Water or Waste Holding Tank 16 14 10 R-B132 $239.99
Buy 9 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $183.00 9 Gallons Buy 9 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $183.00 Ronco Plastics 9 Gallon Plastic Marine Water Tank without Fittings 25 14.625 6 R-B336 $183.00
Buy 9 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $173.00 9 Gallons Buy 9 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $173.00 Ronco Plastics 9 Gallon Plastic Marine Water or Waste Holding Tank 15 19 9 R-B442 $173.00
Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $183.00 9 Gallons Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $183.00 Ronco Plastics 9 Gallon Plastic Marine and RV Water or Waste Holding Tank 32 15 5 R-B288 $183.00
Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $183.00 9 Gallons Buy 9 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $183.00 Ronco Plastics 9 Gallon Plastic Marine and RV Water or Waste Holding Tank 27 15 6 R-B304 $183.00
Buy 10 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $220.00 10 Gallons Buy 10 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $220.00 Ronco Plastics 10 Gallon Plastic Marine Water Tank without Fittings 24 12.625 9.125 R-B278 $220.00
Buy 10 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $187.00 10 Gallons Buy 10 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $187.00 Ronco Plastics 10 Gallon Plastic Marine and RV Water or Waste Holding Tank 26 11 11 R-B438 $187.00
Buy 10 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $201.00 10 Gallons Buy 10 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $201.00 Ronco Plastics 10 Gallon Plastic Marine Water or Waste Holding Tank 24 9.75 10 R-B100 $201.00
Buy 10 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $201.00 10 Gallons Buy 10 Gallon Plastic Marine Water or Waste Holding Tank by Ronco Plastics for only $201.00 Ronco Plastics 10 Gallon Plastic Marine Water or Waste Holding Tank 36 10 10 R-B217 $201.00
Buy 10 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 10 Gallons Buy 10 Gallon Plastic Marine and RV Water or Waste Holding Tank by Ronco Plastics for only $219.99 Ronco Plastics 10 Gallon Plastic Marine and RV Water or Waste Holding Tank 15.375 13.25 13.25 R-B263 $219.99
Buy 10 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $256.00 10 Gallons Buy 10 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $256.00 Ronco Plastics 10 Gallon Plastic Marine Water Tank without Fittings 20 15 14 R-B290 $256.00
Buy 10 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $256.00 10 Gallons Buy 10 Gallon Plastic Marine Water Tank without Fittings by Ronco Plastics for only $256.00 Ronco Plastics 10 Gallon Plastic Marine Water Tank without Fittings 18 17 11.5 R-B495 $256.00
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