ICON - 57 Gallon RV Holding Tank - 84" x 20" x 10.88" - H3658 - Extra Long Low Profile Black/Gray Water

Upgrade your RV’s waste management with the ICON Holding Tank H3658, offering a generous 57-gallon capacity in a durable, thick-walled design. Perfect for black or gray water, this tank features preinstalled drain and level sensors on most models and meets rigorous IAPMO and CSA quality standards. Designed to easily replace leaky or damaged tanks, it delivers reliable performance from a trusted brand.
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The ICON H3658 57 Gallon RV Holding Tank delivers large-capacity waste management in an extra long 84" x 20" x 10.88" design perfect for Class A motorhomes and large fifth wheels with long, narrow underbelly compartments. Engineered with extra-thick polyethylene construction, this IAPMO-certified tank provides durable black water or gray water storage for extended trips and full-time RVing. Whether you're replacing a damaged tank or upgrading your RV's waste capacity, the H3658 offers professional-grade quality with a unique footprint designed for long chassis configurations.

Features & Specifications

• 57 Gallon Capacity: Large waste storage ideal for extended trips, full-time RVing, and larger families
• Extra Long Design: 84" length fits long, narrow underbelly compartments with 20" width and 10.88" height
• Extra-Thick Material: Heavy-duty polyethylene construction resists cracking, warping, and chemical damage
• Tank Only Configuration: Blank tank allows you to customize fittings for your specific RV plumbing setup
• Dual-Purpose Application: Suitable for black water or gray water storage depending on your RV configuration
• IAPMO & CSA Certified: Meets rigorous North American safety and quality standards for RV holding tanks
• Unique Footprint: Narrow 20" width maximizes capacity in long, shallow underbelly spaces

Why Choose the ICON H3658 Holding Tank?

When you need a reliable 57-gallon holding tank with an extra long, narrow design, the ICON H3658 delivers professional-grade quality for unique underbelly configurations. The extra-thick polyethylene construction provides superior durability compared to standard tanks, while the 84" length allows you to maximize waste capacity in long chassis RVs where wider tanks won't fit. The 57-gallon capacity provides ample storage for extended trips and full-time RVing without frequent dump station visits.

ICON Technologies has built a reputation for engineering holding tanks that outlast OEM replacements. The H3658's IAPMO and CSA certifications ensure you're getting a tank that meets strict safety standards for waste containment. Whether you're a DIY RV owner tackling a tank replacement or a mobile technician servicing customer rigs, the H3658 offers the perfect balance of large capacity and unique dimensions that fit long, narrow underbelly spaces.

Compare ICON Holding Tanks

Not sure if the 57-gallon H3658 is the right size for your RV? Compare it against other ICON holding tanks with large capacities to find the perfect fit for your underbelly space and waste capacity needs.

💡 Pro Tip: The H3658's extra long 84" length and narrow 20" width make it ideal for long chassis RVs with shallow, narrow underbelly spaces. Measure your compartment carefully - you'll need at least 84" length clearance. This is a tank-only configuration, so plan to add your own fittings.

Technical Specifications

• Part Number: H3658
• Manufacturer: ICON Technologies (Icon Direct)
• Capacity: 57 Gallons (215.8 Liters)
• Length: 84 inches
• Width: 20 inches
• Height: 10.88 inches
• Material: Extra-thick polyethylene (UV and chemical resistant)
• Construction: Seamless one-piece rotational molding
• Configuration: Tank only (no preinstalled fittings or sensors)
• Application: Black water or gray water holding tank
• Certifications: IAPMO and CSA certified
• Weight: Approximately 45-50 lbs (empty)
• Ideal For: Class A motorhomes, large fifth wheels with long, narrow underbelly compartments

What's Included

• ICON H3658 57-gallon holding tank (tank only)
• IAPMO/CSA certification documentation
• Installation requires separate fittings, sensors, mounting hardware, and plumbing connections (not included)

Note: This is a blank tank only. You will need to add drain fittings, level sensors, vent fittings, inlet connections, and mounting straps separately. This allows you to customize the tank for your specific RV plumbing configuration. Browse our tank fittings collection for compatible accessories.

Compatible Models & Alternatives

The ICON H3658 fits many Class A motorhomes and large fifth wheels with long, narrow underbelly dimensions. If you're looking for related products or alternative tank sizes, explore these options:

• Browse all RV holding tanks - Complete selection of black water and gray water tanks
• Tank fittings and accessories - Valves, sensors, drain fittings, and mounting hardware
• All ICON Technologies products - Complete ICON catalog including fresh water tanks

Frequently Asked Questions

How do I know if the H3658 will fit my RV?

Measure your existing tank or underbelly compartment carefully. The H3658 requires a minimum space of 84" length x 20" width x 10.88" height. This extra long, narrow design is specifically for RVs with long chassis configurations where wider tanks won't fit. Verify clearances around mounting points and plumbing connections before ordering.

Can I use this tank for both black water and gray water?

Yes, ICON holding tanks are designed for dual-purpose use. You can use the H3658 for black water (toilet waste), gray water (sink/shower drainage), or a combination system depending on your RV's plumbing configuration. The extra-thick polyethylene construction handles both applications.

Why doesn't this tank come with fittings or sensors?

The H3658 is sold as a tank-only configuration to give you maximum flexibility in customizing the fittings for your specific RV plumbing setup. This allows you to position drain fittings, sensors, and inlet connections exactly where you need them based on your RV's underbelly layout. Shop our tank fittings collection for compatible accessories.

Is 57 gallons enough capacity for full-time RVing?

A 57-gallon holding tank is excellent for full-time RVing and extended trips for 2-4 people. For reference, a typical RV toilet flush uses about 0.5 gallons, so you'd get approximately 114 flushes before needing to dump. This large capacity allows you to go longer between dump station visits, which is ideal for boondocking and remote camping.

How do I install the H3658 holding tank?

Installation requires removing your old tank, positioning the H3658 in the underbelly compartment, securing it with mounting straps or brackets, and installing drain fittings, level sensors, vent line, and inlet plumbing. Because this is a tank-only configuration, you'll need to drill holes and install fittings according to your RV's plumbing layout. Professional installation is recommended if you're not experienced with RV plumbing systems.

What makes ICON tanks better than standard replacement tanks?

ICON tanks are engineered with extra-thick polyethylene material (thicker than many OEM tanks), providing superior resistance to cracking, warping, and chemical damage. The seamless rotational molding process eliminates weak joints, and IAPMO/CSA certifications ensure the tank meets rigorous safety standards. Many RV owners report ICON tanks outlasting their original equipment tanks by years.

Why Buy from Elkhart RV Parts?

As an authorized ICON Technologies dealer, Elkhart RV Parts guarantees 100% authentic OEM-grade holding tanks backed by manufacturer warranties. Our team specializes in RV plumbing components and can help you select the right tank size and configuration for your specific RV model. Every ICON tank we sell is built to rigorous IAPMO and CSA standards, ensuring safe and reliable waste management for years of RV adventures.