15500 Gallon Plastic Water Storage Tank: Complete Buyer's Guide
The 15,500-gallon water tank is the largest single-piece potable reserve in the line — 141 inches across and 244 inches tall, a twenty-foot column holding over seventy-two tons of water full. The opaque black wall blocks algae-feeding light, and the FDA-compliant resin keeps a vast reserve drinkable.
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
Fifteen thousand five hundred gallons is large-system water security — a community supply, a major agricultural or industrial water reserve, or a primary fire-protection store. It stands a full twenty feet tall on a nearly twelve-foot base, the tallest configuration of the large-diameter family, delivering maximum single-tank capacity where vertical room exists.
Norwesco rotomolds it as one continuous seamless piece of virgin linear polyethylene — no seam or weld across twenty feet of height — with FDA-compliant resin for potable and food-grade contact. At this extreme scale the seamless build is essential: there is no fabricated joint anywhere to fail under seventy-plus tons, and no crevice to harbor biofilm in a large public reserve. The wall is rated to a 1.1 specific gravity for water, and with twenty feet of liquid head the base region carries extremely high hydrostatic pressure, so the wall is heavily graduated toward the bottom.
Black is the appropriate color for a reserve this size: completely opaque, it blocks the light algae needs to bloom, keeping a vast stored volume clearer and minimizing cleaning frequency, and it offers strong UV resistance for long outdoor service. Empty weight is 3,307 pounds; filled with water it loads the foundation with roughly 145,504 pounds, over seventy-two tons across the 141-inch base. Maximum service temperature is 120°F.
Plumbing is built for scale: a 3-inch outlet with a 2-inch reducer for high distribution flow that adapts to your pipework. The 22-inch lid serves large fill, vent, and man-access for inspection, sitting twenty feet up. Norwesco's 3-year warranty applies, and the tank ships via dedicated freight carrier — contact us for delivery timeline and site-access requirements.
Technical Drawing
Official Norwesco technical drawing — 15500 Gallon Plastic Water Storage Tank
Key Features and Specifications
- 15,500-gallon capacity — sized for safe potable water storage
- Constructed from virgin linear polyethylene (HDPE) with 1.1 specific gravity rating — handles liquids up to 9.2 lbs/gal
- 244" tall x 141" diameter — compact vertical footprint
- 3307 lbs empty, approximately 145,504 lbs when full at rated specific gravity
- 3" with 2" reducer NPT outlet fitting — factory installed and leak-tested
- 22" 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
- UV-resistant black pigmentation provides maximum outdoor durability and inhibits algae growth in stored liquids
- 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
- Large tanks require professional installation. Ensure the pad is level within 1 inch across the full diameter and that all piping connections allow for thermal expansion
- Ships via dedicated freight carrier due to oversized dimensions — contact us for delivery timeline and site access requirements
Installation and Setup Guide
A seventy-two-ton full tank twenty feet tall is a major civil and rigging undertaking. Nothing about this install is casual: the foundation is engineered, the set is craned by professionals, and access is permanent and code-compliant.
Site Preparation
This tank requires a structurally engineered reinforced concrete foundation, designed by an engineer for over seventy-two tons concentrated on a 141-inch base with twenty feet of liquid head bearing on the bottom — among the most demanding foundation cases in the catalog. The subgrade must be engineered against any settlement, and the slab poured perfectly level, because at twenty feet of height even a slight tilt generates large eccentric loads. The foundation design is the project's critical path.
Placement and Connections
Setting and standing a twenty-foot, 3,300-pound shell requires a substantial crane and an experienced rigging crew — plan it as an engineered lift. Once positioned, plumb the 3-inch outlet for high-volume distribution, using the reducer to match downstream pipework. Use flexible connections at the bulkhead; thermal movement over twenty feet is significant and a rigid line on a seventy-ton-loaded fitting will fail. Provide permanent, code-compliant access — a fixed ladder and platform — to reach the lid twenty feet up.
Venting
A 3-inch outlet moves large volume, and a fifteen-thousand-gallon-plus tank exchanges a vast air volume during fill and draw. Size the vent in the 22-inch lid generously for peak flow — on a tank this tall, an undersized vent during a fast transfer can pull catastrophic vacuum. A screened vent keeps insects, debris, and animals out of the reserve while the tank breathes.
Maintenance and Long-Term Care
At fifteen thousand five hundred gallons, maintenance is a rigorous, documented program befitting the scale and the people who depend on the reserve.
Quarterly Inspection Checklist
- Plumb and foundation: Verify the twenty-foot column stands true against a surveyed vertical and the engineered slab shows no cracking, settlement, or movement. Any base movement under seventy-plus tons is a serious finding requiring the foundation engineer's attention.
- Base region: Inspect the lower wall and wall-to-floor knuckle, carrying the maximum load from twenty feet of water head, for any bulge or distortion.
- Water quality: Check clarity through the 22-inch lid; in an opaque tank, growth indicates a compromised screen or seal admitting light or contaminants.
- Outlet, reducer, vent: Inspect all fittings for weeping and confirm the vent is clear and correctly sized for the large flow.
Cleaning and Sanitizing
Sanitizing a reserve this large is a formal operation with confined-space and fall-protection protocols for any man-access at twenty feet through the 22-inch lid. Drain, clean the interior, then disinfect walls and fittings with a chlorine solution — about a quarter cup of unscented household bleach per 15 gallons used — let it dwell, drain, and flush with fresh water until no chlorine odor remains. Follow all regulatory water-quality requirements that apply to your system.
UV and Weather
Black polyethylene resists UV strongly, so even a twenty-foot wall handles full sun. Inspect exposed faces yearly for chalking. A vast stored volume changes temperature very slowly, moderating swings; in cold climates manage the plumbing against freezing, since exposed fittings stay vulnerable even when a reserve this large never freezes solid.
Alternatives and Comparisons
At the top of the single-tank range, your decisions are about configuration and redundancy:
One maximum tank versus several: a single 15,500-gallon vessel gives the most capacity per foundation and the lowest per-gallon cost, but concentrates all your reserve and risk in one tank. Splitting into multiple tanks lets you isolate part of the supply for cleaning or repair without losing the whole reserve, and limits the consequences of any single failure — usually the preferred approach for a critical or public supply.
The 3-inch outlet and reducer: this tank's plumbing supports the high distribution flow a large system demands while adapting to existing pipework.
Other 15500-Gallon Options
Frequently Asked Questions
How long will the 15500 Gallon Plastic Water Storage Tank last?
With a structurally engineered foundation and normal use, fifteen to twenty years is realistic. The foundation is the dominant life factor at this scale — any settlement under seventy-plus tons shortens service. Black polyethylene's UV durability and the seamless, jointless wall reach the upper range when the base holds true and the reserve is sanitized on schedule.
What chemicals can I store in this tank?
This is a potable water tank — FDA compliant for drinking water and food-grade liquids, rated to a 1.1 specific gravity for water. It is not for aggressive chemicals, fuels, or solvents, which require a higher-specific-gravity tank verified for the chemistry. At large-system scale, keep it strictly for water and follow your system's water-quality regulations.
What kind of foundation does a 15500-gallon tank need?
It requires a structurally engineered, reinforced concrete foundation designed for roughly 145,504 pounds on a 141-inch base with twenty feet of liquid head — one of the most demanding foundation cases in the line, and strictly an engineer's calculation. The subgrade must be engineered against settlement and the slab poured perfectly level. The foundation is the critical path of the project.
Does this tank come with a warranty?
Yes — Norwesco's 3-year warranty covers factory material and workmanship defects. It excludes non-engineered or inadequate foundations, freezing damage, and impact or rigging damage. Retain complete engineering and installation documentation for any claim at this scale.
Can I install this tank underground?
No — this is an above-ground industrial water tank, not engineered for burial, and at this size burial is not feasible. 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 large-infrastructure procurement. The non-negotiables: a structurally engineered foundation as the project's critical path, an engineered crane lift to set and stand a twenty-foot, 3,300-pound shell, permanent code-compliant access to the lid, and freeze protection for the plumbing where winters demand it. Confirm the 3-inch outlet and reducer match your distribution system and pumping. This ships by dedicated freight carrier — engage us early to coordinate delivery, site access, and the rigging and foundation work your project will require.
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