6500 Gallon Plastic Water Storage Tank: Complete Buyer's Guide
6,500-gallon black water storage tank built for safe potable water storage. Manufactured by Norwesco from virgin linear polyethylene (HDPE) rated to handle liquids up to 9.2 pounds per gallon. FDA approved for contact with potable water, ensuring safe storage for drinking water and food-grade liquids.
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
The 6,500 Gallon Plastic Water Storage Tank is bulk water for the property that has graduated from tanks you can move to infrastructure you build around. Sixty-five hundred gallons makes a substantial fire reserve, a ranch or vineyard irrigation bank, a community well buffer, or a rainwater cistern that bridges a genuine drought. Standing twelve and a half feet tall on a ten-foot base, it is a permanent installation sited once and plumbed in for the long term.
Norwesco rotationally molds it in one continuous piece of virgin linear polyethylene, so the shell carries no seam or weld even at this volume. It is rated to 1.1 specific gravity for water-based liquids up to 9.2 pounds per gallon, with a 120 F / 48 C service ceiling. The black pigment is essential at this scale: it keeps light out of thousands of gallons to prevent an algae bloom and gives the wall maximum UV durability for years of open exposure.
Empty, the tank weighs 1,104 pounds; full at 1.1 SG it bears down at roughly 60,735 pounds — over thirty tons demanding a professionally engineered foundation. A factory 2-inch NPT outlet feeds distribution, and the 16-inch lid serves for filling, venting, and interior access. Norwesco's 3-year warranty against manufacturing defects backs the tank, which we re-inspect before shipping.
Technical Drawing
Official Norwesco technical drawing — 6500 Gallon Plastic Water Storage Tank
Key Features and Specifications
- 6,500-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
- 150" tall x 119" diameter — compact vertical footprint
- 1104 lbs empty, approximately 60,735 lbs when full at rated specific gravity
- 2" 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
- 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
Thirty tons of water sets the entire installation agenda for a 6,500-gallon tank. This is professional work from the ground up: a poured, engineered foundation, mechanical placement, and plumbing built to flex with a twelve-foot tank.
Engineered Foundation
The tank needs a reinforced concrete slab a structural engineer has designed for roughly 60,735 pounds spread over the 119-inch diameter, flat within one inch across that full width. At this weight a high spot in the slab does not just look uneven — it concentrates tons into a small patch of wall and seeds a failure. Cure the concrete completely before filling, and grade the surrounding grade so water always drains away from the pad.
Placement and Plumbing
The empty shell tops a thousand pounds and ships oversized, so a forklift or crane sets it on the cured slab. Plumb the 2-inch outlet in schedule 80 PVC and design the run with expansion provisions, because a tank this tall grows and shrinks with temperature and the piping must move with it. Support each line on its own so none of its weight hangs on the tank fitting.
Venting
Air has to move in and out of the tank as fast as water does. Fit a generously sized, screened vent in the 16-inch lid, matched to your peak fill and draw rates; an undersized breather lets a tank this large pull a vacuum and buckle during a hard pump-down. The lid also serves as the access point for the periodic interior cleaning a potable tank requires.
Maintenance and Long-Term Care
A 6,500-gallon potable tank is a small water utility, and it earns utility-grade attention: regular checks on the structure beneath the load and a disciplined annual interior service.
Structural Monitoring
- Foundation: Inspect the slab and surrounding ground for cracks, settlement, or erosion several times a year. At thirty tons, a settling corner redistributes load the tank was never designed to carry.
- Wall: Walk the full circumference, focusing low on the wall where hydrostatic pressure is highest, and watch for any bulge or distortion. The black surface chalks gradually long before it fails.
- Outlet and vent: Check the 2-inch fitting for weeping and verify the large vent stays clear; a blocked vent is the quickest way to collapse a tank this size.
Annual Interior Service
Once a year, take the tank offline, drain it, and remove the sediment from the floor. The 16-inch lid allows interior access for cleaning — observe confined-space precautions, ventilate first, and never work alone. Sanitize with the potable standard of a quarter cup of unscented bleach per fifteen gallons, hold two hours, and flush thoroughly before returning it to service.
Climate
The black UV-loaded wall is built for permanent sun; in extreme-UV regions an annual look at the sun-facing side catches early chalking. A reservoir this large in active turnover rarely ices, but an idle tank should be drained where winters are severe.
Alternatives and Comparisons
At 6,500 gallons the practical decision is one large reservoir against a cluster of medium tanks.
Single reservoir vs. tank battery: One 6,500-gallon tank is the cheapest path per gallon and the simplest to plumb, but it concentrates your supply in a single vessel and a single foundation. A pair of 3,000- to 3,500-gallon tanks manifolded together costs more and uses more ground, yet it lets you clean or repair one while the other keeps water flowing, and it divides the foundation load. Fire reserves and steady bulk demand usually favor the single tank; systems that must never go fully dry favor the array.
Other 6500-Gallon Options
Frequently Asked Questions
How long will the 6500 Gallon Plastic Water Storage Tank last?
On a properly engineered slab and within its 1.1 SG and 120 F ratings, this tank readily reaches 15 to 20 years, often more in steady potable service. The black, UV-loaded wall is built for permanent exposure and the seamless shell has no joints to fail. At this scale the foundation is the deciding factor — a well-built, level slab is what carries the tank through decades.
What chemicals can I store in this tank?
It is an FDA-approved potable-water tank, intended for bulk drinking water, fire reserve, agricultural supply, and rainwater harvesting, plus water-based liquids within its 1.1 specific-gravity rating. It is not for fuels, solvents, or aggressive chemicals; those require a 1.5-SG liquid tank with verified compatibility.
What kind of foundation does a 6500-gallon tank need?
A full 6,500-gallon tank weighs about 60,735 pounds — over thirty tons. That demands a reinforced concrete slab engineered by a structural professional, flat within one inch across the full diameter. This is not a gravel-pad project; the foundation is the most important element and must be designed and cured before delivery.
Does this tank come with a warranty?
Yes. Under normal use, Norwesco's 3-year warranty addresses manufacturing defects in materials and workmanship. It excludes damage from an inadequate foundation, overfilling beyond the rated specific gravity, incompatible chemicals, or impact. Keep documentation and photos of the engineered foundation and installation.
Can I install this tank underground?
No. A poly tank of this size is built for above-ground duty and cannot take the soil pressure of burial, which would crush it and void coverage. Below-grade storage calls for our purpose-built, reinforced underground cisterns.
Buying Considerations
Three commitments come with a 6,500-gallon tank. First, the engineered foundation: plan and pour a reinforced slab sized for 60,735 pounds, designed by a structural professional, and have it cured before the tank arrives. Second, access — the oversized shell needs a clear approach for a flatbed and a crane or large forklift. Third, your system: confirm the 2-inch outlet and the vent suit your distribution and fill rates. This tank ships on a dedicated carrier; we coordinate delivery and site access to your ZIP.
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