The Chem-Tainer 400 Gallon Open Top Batch Storage Tank (SKU R367236A) is a rectangular polyethylene reservoir built for open-access batch mixing, settling, and bulk water holding where you need to reach into the tank or feed it from above. It holds 400 gallons in a 72 in. long by 36 in. wide by 36 in. tall footprint, molded in natural white polyethylene. The open top means no lid restriction on filling, agitation, or manual additions, which is why this style of open tank shows up as a workhorse for rectangular water batching and staging.
Will it work for your job?
Match the tank to the load it actually carries. Filled with water, this 400-gallon tank weighs roughly 3,336 lb, so the surface under it has to carry that whole load plus the empty tank. Set it on a flat, fully supported pad sized for the 72 in. x 36 in. footprint - a partially supported base will let a flexible open-top wall flex and crack over time. One thing to plan for before fill: empty, a rectangular open-top tank this size is light and can shift or tip in wind, so place it where it will be filled promptly or otherwise secured. Do not plan to fill all the way to the 36 in. rim either - that wall height is the absolute maximum liquid line, and you want freeboard for agitation, sloshing, and any manual additions. If you are pouring a slab, our concrete pad sizing guide walks through the ACI framework for above-ground polyethylene tanks. Not sure 400 gallons is the right capacity? Run the numbers in our Tank Sizing Calculator or read the Tank Sizing Guide before you commit.
Where it fits in a water system
As a rectangular open-top tank it nests efficiently against a wall or alongside other tanks, which makes it useful in quality-banded reuse trains and multi-stage staging where footprint matters. If you are aggregating grey water, rainwater, or HVAC condensate into staged storage, our guide on industrial water reuse tank topology covers how open-top batch tanks sequence into treatment stages. For rural fire-water reservoir planning and cold-climate freeze protection, see our fire-water reservoir design guide. If your process needs bottom drainage and solids handling instead of open-top access, a sloped vessel is the better shape - our comparison of Chem-Tainer cone-bottom tanks at 30 vs 45 degrees lays out the trade-offs. Check the technical drawing on this page for the exact rectangular dimensions before you frame an enclosure or size a containment area.
One thing not to overlook
This tank ships bare as an open-top batch vessel - there are no molded bulkhead fittings, drains, or outlets on it as listed, so plan to fill and draw from the top or specify your outlets separately and call us to spec them. It is built for water at ambient conditions on a specific-gravity 1.0 basis, not for sealed pressure, closed-top, or chemical service. If your process involves anything heavier than water or any chemical, confirm compatibility by phone before you fill it; for water batching, settling, and staging it does exactly the job it is shaped for.
This tank ships LTL freight from the Chem-Tainer plant in West Babylon, NY, quoted live to your ZIP code - get your exact number in seconds with our Freight Cost Estimator, or call us at 866-418-1777 and we will walk you through sizing, fittings, freight, and lead time. One Source Plastics.
