Chem-Tainer 138 Gallon PP Rectangular Open Top Tank

The Chem-Tainer 138 Gallon Rectangular Open Top Tank is a polyethylene batch and staging vessel built for straight open-top water work where you need to fill, mix, dip, or draw down from the top without threading through a lid. At 138 gallons, a full tank of water weighs about 1,151 pounds (138 gal x ~8.34 lb/gal), so the pad or platform under it has to be flat, continuous, and rated for that load before you fill it the first time.

Will this rectangular open top tank work for your job?

The open-top rectangular format is the reason people reach for this tank instead of a round closed vessel: the flat walls sit tight against other tanks or a wall to save floor space, and the open top gives you full-hand access for mixing, manual dip transfers, parts washing, or as a catch and staging basin. It ships with no factory fittings, so any bulkhead outlet or drain is a field addition — sized to your line and sealed with a compatible gasket rated for the fluid and wall thickness, sourced separately. Because the top is open, this is a storage and process tank, not a sealed or pressurized one: keep it vented to atmosphere and covered only with a loose lid if you need to keep debris out.

Sizing it right

Run your real fill volume through the Tank Sizing Calculator and the Tank Sizing Guide before you commit — 138 gallons of water is over half a ton fully loaded, and an open-top tank is easy to over-fill by eye. If this tank sits outdoors above grade, review concrete pad sizing for above-ground polyethylene tanks so the base carries the load without rocking or point-loading a corner. For rainwater capture, greywater, or condensate staging into a larger storage train, the industrial water reuse tank topology guide shows how an open-top basin like this fits as an aggregation or first-stage vessel. If you are staging water for a rural or remote fire-protection reservoir, the fire-water reservoir tank design guide walks through how a poly tank fits the private fire-protection stack.

The mistake to avoid

An open-top rectangular tank carries less structural strength in its flat walls than a round tank does, so this format is meant for water and top-atmosphere service — not for sealing shut, pressurizing, or standing full without a fully supported base under the entire footprint. Support the whole bottom, not just the corners, and keep the fill line honest so you are not carrying more than the 1,151 lb full-water load the pad was built for.

This Chem-Tainer open top tank ships LTL freight from the West Babylon, New York plant, quoted live to your ZIP — get your number in seconds with the Freight Cost Estimator or call 866-418-1777 to lock in delivery. Tell us your delivery ZIP and whether you need a liftgate, and we will quote the freight before you buy.