400 Gallon Green Doorway Water Tank: Complete Buyer's Guide
The 400-gallon green doorway water tank pairs narrow-access storage with a forest-green wall that blocks light and blends in — 66 inches long, 29 inches wide, and 70 inches tall. It passes a standard doorway, holds 400 gallons of FDA-compliant potable water, and its opaque green color suppresses algae for tanks that may sit in a lit space or partial daylight.
Specifications at a Glance
Every figure below is pulled straight from the live product record for this exact tank — the same data on the product page, so what you read here and what you buy never disagree.
Standards & Materials
- ASTM D1998 — Standard Specification for Polyethylene Upright Storage Tanks. Governs wall-thickness and hydrostatic design for vertical rotomolded poly tanks of this class.
- FDA 21 CFR 177.1520 — Olefin polymers. The food-contact regulation the FDA-grade resin in this tank is compounded to meet.
- Specific gravity rating 1.1 — the tank is engineered for liquids up to 1.1× the density of water (water is about 8.34 lb/gal). Confirm your fluid’s SG before storage.
Product Overview
This doorway tank adds a feature the white versions don't have: an opaque forest-green wall. Color matters for water storage because light feeds algae, and a tank placed in a sunlit room, a garage with windows, or a partially daylit outbuilding benefits from a wall that blocks that light entirely. The green also blends into a landscaped or utility setting better than a stark color. At 29 inches wide it still clears a standard door, so you get algae control and narrow access in one tank.
Norwesco rotomolds it as a single seamless piece of virgin linear polyethylene with FDA-compliant resin for potable and food-grade contact — the seamless wall leaves no joint to leak and no crevice to harbor biofilm. The wall is rated to a 1.1 specific gravity, matched to water-density storage. The elongated 66-by-29-inch form, standing 70 inches tall, packs 400 gallons into a doorway-friendly width by trading the cylinder for a taller, narrower profile.
Unlike the translucent white doorway tanks, the green wall is opaque, so you won't read the level through the wall — the tradeoff for blocking light — and you'll gauge it through the lid or with a level indicator instead. That's usually a worthwhile exchange wherever ambient light would otherwise encourage growth in stored water. Empty, the tank weighs 183 pounds; filled with water it carries roughly 3,853 pounds on its footprint, a load the supporting floor must handle. Maximum service temperature is 120°F.
The outlet is a 1.25-inch NPT fitting positioned on the 29-inch end, factory-installed and leak-tested. The 16-inch lid serves fill, vent, and inspection. Norwesco's 3-year warranty applies, and the tank ships LTL freight on a pallet, with residential delivery and liftgate available.
Technical Drawing
Official Norwesco technical drawing — 400 Gallon Green Doorway Water Tank
Key Features and Specifications
- 400-gallon capacity — sized for tight-access indoor liquid storage
- Constructed from virgin linear polyethylene (HDPE) with 1.1 specific gravity rating — handles liquids up to 9.2 lbs/gal
- 66" long x 29" wide x 70" tall
- 183 lbs empty, approximately 3,853 lbs when full at rated specific gravity
- 1.25" on 29" end NPT outlet fitting — factory installed and leak-tested
- 16" lid opening for fill, venting, and interior access
- FDA approved for potable water and food-grade liquid contact
- 3 Year Warranty from Norwesco against manufacturing defects
- Forest green color blends naturally with landscaping for residential and agricultural installations
- Rated for continuous service up to 120 F / 48 C
- Seamless one-piece rotational molding — no seams, no welds, no leak points
- Manufactured by Norwesco — a leading name in rotomolded polyethylene tanks
- Place on a firm, level surface free of rocks or sharp objects that could damage the tank bottom. Ensure adequate ventilation if stored chemicals produce vapors
- Ships via LTL freight on a pallet — residential delivery with lift gate available
Installation and Setup Guide
The green doorway tank installs like its white siblings — get it in, confirm the floor, plumb the water — with the added benefit that its light-blocking wall gives you more freedom in where you place it.
Getting It In and Floor Loading
Check your access route against the 29-inch width, 70-inch height, and 66-inch length. The narrow width clears a standard door; the 70-inch height is taller than the lower doorway tanks, so watch overhead clearance and tight stairwell turns. Two people can move the 183-pound empty tank. Confirm the floor carries roughly 3,853 pounds full — a modest load, but worth verifying on framed or upper floors before filling.
Placement and Connections
Set the tank on a flat, level surface free of debris. Connect your fill line and the 1.25-inch end outlet to your plumbing, using a flexible coupling to absorb thermal movement. The light-blocking green wall means you can place this tank in a brighter spot — near a window, in a daylit garage — without inviting algae, which is its key placement advantage. Route an overflow so any escaping water drains safely.
Venting
Fit a screened vent in the 16-inch lid sized to your fill and draw rate so the tank breathes. The screen keeps debris and insects out of the potable water. Even with the green wall blocking light through the walls, keep the lid sealed and the vent screened so light and contaminants don't enter from the top.
Maintenance and Long-Term Care
The green wall reduces the algae burden, so maintenance leans toward keeping water fresh, watching the fittings, and the usual indoor-leak vigilance.
Quarterly Inspection Checklist
- Water quality: Since the opaque wall blocks the view, check clarity and sediment through the 16-inch lid. The green wall suppresses algae, so growth would point to light or contaminants entering through the lid or a vent gap — investigate the top of the tank.
- Fittings and floor: Inspect the 1.25-inch end outlet and fill connection for weeping, and confirm the floor under the tank stays dry and sound.
- Vent screen and lid: Verify the vent is clear, the screen intact, and the lid sealing — the main path for light or contamination on an opaque tank.
- Level base: Confirm the tank sits level on its footprint.
Cleaning and Sanitizing
Sanitize at least annually. Drain, scrub the interior through the 16-inch lid, then disinfect with a chlorine solution — about a quarter cup of unscented household bleach per 15 gallons used — let it stand a couple of hours, drain, and flush with fresh water until no chlorine odor remains. Because you can't see inside through the wall, use the lid to confirm the interior is clean before refilling.
Indoor and Light Considerations
The green wall's job is blocking light, so this tank tolerates brighter placements than a translucent one. It still won't chalk indoors, and you should keep the space within the 120°F limit and guard against freezing in unheated areas. Plan drainage around the tank in case of a leak.
Alternatives and Comparisons
The choice here is largely about color and access:
Green versus white doorway tank: the opaque green wall blocks algae-feeding light, making it the better choice for a tank in a daylit space, while the translucent white versions let you read the level through the wall but admit light. If your storage spot gets any meaningful light, the green tank's algae control usually outweighs losing the see-through level.
Doorway versus standard tank: as with all doorway tanks, choose this format when narrow access forces it; a standard cylinder is cheaper per gallon where you have room to place it. The doorway design buys access, the green color buys light control.
Other 400-Gallon Options
Frequently Asked Questions
How long will the 400 Gallon Green Doorway Water Tank last?
Fifteen to twenty years is realistic, and the combination of indoor or sheltered placement and the UV-resistant opaque green wall favors the upper end. With a level base and routine sanitizing, the seamless rotomolded wall delivers a long, low-maintenance service life.
What chemicals can I store in this tank?
This is a potable water tank — FDA compliant for drinking water and food-grade liquids and rated to a 1.1 specific gravity for water and benign aqueous solutions. Doorway tanks are intended for water and water-based storage; never use one for fuels, solvents, or flammables, and confirm compatibility before storing any chemical. The green wall's value is algae control for stored water.
What kind of foundation does a 400-gallon tank need?
A full tank is roughly 3,853 pounds on the 66-by-29-inch footprint — a modest load most floors carry, though worth verifying on a framed or upper floor before filling. A flat, level surface free of debris is the requirement; floor capacity is the special indoor consideration.
Does this tank come with a warranty?
Yes — Norwesco's 3-year warranty covers defects in materials and workmanship. It excludes uneven or improper installation, freezing damage, and impact damage. Keep documentation of a level install for any claim.
Can I install this tank underground?
No — this is an above-ground tank designed for interior or sheltered placement, not burial; soil pressure would deform the wall. For below-grade water storage, use a purpose-built underground cistern designed for soil load.
Buying Considerations
If your storage spot gets any light, the green wall is the reason to choose this over a translucent doorway tank — it keeps algae out of stored water. Measure your route against the 29-inch width, 70-inch height (taller than the low doorway tanks), and 66-inch length; confirm the floor carries roughly 3,853 pounds full; plan freeze protection if the space is unheated; and provide a level base. The 1.25-inch end outlet plumbs easily. It ships LTL on a pallet with residential and liftgate delivery available.
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