Mobile Plastic Tanks

Custom Holding Tanks for Mobile Applications

We fabricate mobile plastic tanks to virtually any shape or size!

Our custom holding tanks are designed to take full advantage of every cubic inch of space and floor plan. Angles, radii, cut outs, notches, are never a problem.

Our Tanks can also be heated for use in freezing applications.

Send us your sketch and you’ll typically have a new custom tank in 2 weeks or less!


Our experience for helping you choose the right material for your particular custom plastic tank is just a phone call or click away.

Build a Tank
Our tanks are engineered using FEA (Finite Element Analysis) to maximize performance and allow for minimal bowing of the fabrication.

The Kinds of Mobile Plastic Tanks We Can Fabricate to Your Exact Specifications Include:


Waste Water Tanks


Grey Water Tanks


Black Water Tanks


Waste Tanks

Flexible Vehicle Connectivity

We make connectivity to your vehicle flexible by machining threads directly into tank walls for low profile plumbing installations.

We can also provide welded-on threaded fittings or barbed connectors.

Reduced Sloshing & Complete Emptying

Unlike a molded tank, we can install internal supports and baffles to strengthen the welded holding tank and reduce sloshing.

We can also install castellated pick-ups and truncated baffles to allow complete emptying.

Greater Protection

Welded plastic holding tanks are far superior to molded holding tanks due to consistent wall thickness and overall heavier construction, which makes road hazard penetration less likely.

Send us your sketch and you’ll typically have a new custom tank in 2 weeks or less!








Boats & Yachts


Micro Homes


Restroom Trailers


Office Trailers


Special Event Trailers

Highest Accuracy & Quality

We cut all plastic holding tank components with the latest in CNC equipment, and use only Virgin U.S. material to ensure the absolute highest quality.

This accuracy and quality is repeated on every plastic holding tank for consistent operation and reliable function.

Highest Standards

It’s important to note that we weld our plastic tanks to the strict German DVS welding standards.

This specification is used to measure the integrity of commercial chemical and acid tanks, so you can be assured of long-lasting integrity for this critical component.

Best welds in the industry!

Preferred OEM Supplier of Commercial Mobile Restroom Tanks
Miller Plastics is the OEM supplier of mobile holding tanks for many leading restroom trailer and RV manufacturers.

Our warranty and the heavy duty industrial nature of our designs make us the #1 choice for a tank vendor.