100 Gallon Doorway Water Tank: Complete Buyer's Guide
The 100-gallon doorway water tank is the most compact narrow-access water tank in the line — 38 inches long, 22 inches wide, and 45 inches tall, light enough at 41 pounds for one person to carry through a doorway. It holds 100 gallons of FDA-compliant potable water in spaces a larger tank could never reach.
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 1.5 — the tank is engineered for liquids up to 1.5× the density of water (water is about 8.34 lb/gal). Confirm your fluid’s SG before storage.
Product Overview
One hundred gallons is a modest but genuinely useful indoor reserve — an emergency backup, a treated-water buffer, a point-of-use supply where running a line from a larger tank isn't practical. This doorway version is built for the tightest access: at just 22 inches wide it passes through nearly any door, hatch, or narrow stairwell, and at 45 inches tall and 38 inches long it tucks into closets, under counters, or in the corner of a utility room.
Norwesco rotomolds it as a single seamless piece of virgin linear polyethylene with FDA-compliant resin for potable and food-grade contact — no joint to leak, no crevice to harbor biofilm in stored drinking water. The wall is rated to a 1.5 specific gravity, far beyond water's needs, so a small tank like this has generous structural margin. The translucent white wall lets you read the level by eye, ideal for a tank you check casually in a closet or corner.
The standout practical feature at this size is portability. Empty, the tank weighs only 41 pounds — one person can carry it through a doorway and set it in place without help or equipment. Filled with water it carries roughly 1,292 pounds on its small 38-by-22-inch footprint, a load most floors handle easily, though the concentrated weight on a small area is still worth a thought on a questionable floor. Maximum service temperature is 120°F.
The outlet is a 1.25-inch NPT fitting, factory-installed and leak-tested, with an 8-inch lid for fill, vent, and inspection. Light enough to skip freight, this tank ships via UPS or FedEx ground — typically arriving within about a week, boxed to your door with no pallet to handle. Norwesco's 3-year warranty applies.
Technical Drawing
Official Norwesco technical drawing — 100 Gallon Doorway Water Tank
Key Features and Specifications
- 100-gallon capacity — sized for tight-access indoor liquid storage
- Constructed from virgin linear polyethylene (HDPE) with 1.5 specific gravity rating — handles liquids up to 12.5 lbs/gal
- 38" long x 22" wide x 45" tall
- 41 lbs empty, approximately 1,292 lbs when full at rated specific gravity
- 1.25 NPT outlet fitting — factory installed and leak-tested
- 8" 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
- Translucent white walls allow visual level monitoring without opening the tank and reflect sunlight to keep contents cooler
- 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 UPS or FedEx ground — typically arrives within 5-7 business days
Installation and Setup Guide
This is the easiest tank in the entire line to install — one person carries it in, sets it on any level surface, and plumbs a single outlet. The doorway-access worry that complicates larger tanks essentially disappears at 22 inches wide and 41 pounds.
Placement
Carry it to its spot and set it on a flat, level surface free of debris — a closet floor, a counter rated for the weight, a utility-room corner. The 22-inch width clears virtually any opening, so you rarely need to plan a route. Confirm the surface supports roughly 1,292 pounds when full; a floor is fine, but a shelf or counter must be genuinely rated for that load before you fill the tank.
Connections
Connect your fill line and plumb the 1.25-inch outlet to your point of use, using a flexible coupling at the outlet to absorb thermal movement. For an indoor tank, route an overflow so any excess drains safely rather than onto the floor. Keep the outlet run short for good flow from a modest 100-gallon column.
Venting
Fit a screened vent in the 8-inch lid so the tank breathes during fill and draw — even a small tank dimples under vacuum if it's sealed and drawn down. The screen keeps debris and insects out of the potable water. In a closed closet, make sure the vent reaches enough air.
Maintenance and Long-Term Care
A 100-gallon indoor water tank is about as low-maintenance as storage gets — small, sheltered, and easy to reach — but the water still needs periodic refreshing to stay safe.
Inspection Routine
- Water clarity: Glance at the level and clarity through the translucent wall. Indoors and out of light, cloudiness usually just means the water has sat too long — refresh it.
- Fitting and surface: Check the 1.25-inch outlet for any weeping, and confirm the surface under the tank is dry and sound — even a small indoor leak is worth catching early.
- Vent screen: Verify the vent is clear and the screen intact.
- Level base: Confirm the tank sits level on full support.
Cleaning and Sanitizing
Sanitize at least annually, more often if the water sits a long time — small backup tanks often hold water that isn't cycled frequently, which makes periodic sanitizing more important, not less. Drain, scrub the interior through the 8-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. The small size makes this a quick job.
Indoor Considerations
Spared UV, the tank won't chalk. Keep the space within the 120°F limit, and protect against freezing in unheated areas — a small tank freezes fastest of all, so a 100-gallon reserve in an unheated space needs freeze protection in cold climates.
Alternatives and Comparisons
At the small end, the comparison is about how much reserve you actually need:
100-gallon doorway versus a larger doorway tank: the 100 is the choice when access is extremely tight or you only need a small backup — it's the only one a single person carries through any door and ships by parcel. If you need a meaningful multi-day reserve, a larger doorway tank holds more while still passing a standard door.
Doorway tank versus a portable container: unlike a jug or drum, this tank has a plumbed 1.25-inch outlet and an FDA-compliant potable rating, so it integrates into a fixed water system rather than being hand-filled and poured. For a permanent small reserve, the tank is the better tool.
Other 100-Gallon Options
Frequently Asked Questions
How long will the 100 Gallon Doorway Water Tank last?
Fifteen to twenty years is realistic, and indoor placement removes UV and weather entirely, favoring the upper end. For a small sheltered tank, the practical limit is usually how diligently the water is refreshed and sanitized rather than the seamless wall wearing out.
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 1.5 specific gravity, giving a small tank ample structural margin for water and benign aqueous solutions. Doorway tanks are intended for water and water-based storage; never use one for fuels, solvents, or flammables, particularly indoors.
What kind of foundation does a 100-gallon tank need?
A full tank is roughly 1,292 pounds on its small 38-by-22-inch footprint. Most floors carry that easily, but because the weight is concentrated on a small area, verify a questionable floor — or any shelf or counter — before filling. A flat, level surface free of debris is the only requirement.
Does this tank come with a warranty?
Yes — Norwesco's 3-year warranty covers defects in materials and workmanship. It excludes improper installation, freezing damage, and impact damage. Keep your receipt for any claim.
Can I install this tank underground?
No — this is an above-ground tank designed for interior 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
This is the simplest water-storage purchase in the line. The 22-inch width clears almost any opening and the 41-pound empty weight means one person handles it, so access planning is rarely an issue. Confirm the surface supports roughly 1,292 pounds full — floor, or a properly rated shelf — plan freeze protection if the space is unheated, and verify a level base. The best part: it ships small-parcel ground, boxed to your door with no pallet or liftgate, typically within a week.
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