The Chem-Tainer 135-gallon rectangular open-top tank is a molded batch vessel built for open-access mixing, dosing, and process-water staging — jobs where you need to see into the tank and reach into it. The rectangular footprint packs real volume into a tight corner or against a wall, and the open top makes it straightforward to drop in a mixer, add water by hose, or draw from the surface. If you have been searching for a rectangular open top tank that holds meaningful volume without a round tank's wasted corners, this is the size that fills the gap between a small utility tub and a full bulk tank.
Does this tank work for your job?
This is a 135-gallon rectangular open tank. Full of water it carries roughly 1,126 lb, so the pad or platform under it has to be flat, continuous, and rated for that load with the tank full — a flat-walled open top tank does not tolerate a soft or uneven base, because water shifts toward any low corner and loads one wall harder than the rest. Size the tank to your actual working volume, not the theoretical brim; open-top tanks are almost always run with freeboard so mixing and hose flow do not slop over the rim. Our Tank Sizing Calculator and Tank Sizing Guide help you match gallons to your batch and leave the right headroom. If you are aggregating grey water, rainwater, or condensate into a staged treatment train, our water-reuse tank topology guide covers where an open staging tank fits.
Set it up right the first time
The most common mistake with a rectangular open top tank is treating the flat walls like a round tank's. Round tanks carry hydrostatic load in hoop tension; flat rectangular walls carry it in bending, which is why a full one needs its base fully and evenly supported and should never be improvised onto pallets or spanning gaps. Level a continuous pad, confirm it stays flat under the full ~1,126 lb, and keep the top opening clear for whatever you are lowering in — our concrete pad sizing guide walks through the ACI framework. Because the top is open, plan for splash, evaporation, and debris; a cover is worth adding outdoors or near foot traffic. In cold climates, an open surface loses heat fast and is the first place to ice — the freeze-protection engineering in our rural fire-water reservoir guide applies to any staged open tank. One note: the product title lists this tank as PP, so confirm the exact resin with us before ordering if your service is material-sensitive.
Freight and how to order
This tank ships LTL freight from the Chem-Tainer plant in West Babylon, New York, and freight is quoted live to your ZIP rather than bundled into the list price. The ~1,126 lb figure is the tank full of water — the empty tank you receive is light, so it moves easily on a standard LTL line, but its size still makes a liftgate or forklift at delivery worthwhile. Enter your delivery ZIP in our Freight Cost Estimator for a real LTL number, or call 866-418-1777 and we will quote it and confirm the right open-top size for your process.
