500 Gallon Plastic Water Storage Tank: Complete Buyer's Guide
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 500 Gallon Plastic Water Storage Tank is the volume that finally turns a hauled-water habit into a real supply. Half a thousand gallons covers a rural household's buffer between well-truck deliveries, a livestock trough that does not run dry on a hot afternoon, or a garden and orchard reserve that survives a dry week. At 48 inches across and 73 inches tall it stands narrow and upright, so it tucks against a wall or into a side yard without sprawling.
Norwesco rotationally molds the tank from a single charge of virgin linear polyethylene, leaving no seam to weep and no joint to age. It is rated to 1.1 specific gravity for water and water-based liquids up to 9.2 pounds per gallon, with a 120 F / 48 C service ceiling. The black pigment is the practical choice for a water tank held outdoors: it blocks light, which starves the algae that turns a translucent tank green, and the carbon loading gives the wall its strongest UV resistance.
Empty it weighs 94 pounds and a single person can roll it into position; full at 1.1 SG it settles to about 4,681 pounds, so it needs a firm, level base but not an engineered slab. A factory 2-inch NPT outlet draws the tank down, a 1.5-inch NPT inlet is included for plumbed fills, and the 16-inch lid opens for tank trucks, float valves, and cleaning. Norwesco's 3-year warranty against manufacturing defects backs every unit.
Technical Drawing
Official Norwesco technical drawing — 500 Gallon Plastic Water Storage Tank
Key Features and Specifications
- 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
- 73" tall x 48" diameter — compact vertical footprint
- 94 lbs empty, approximately 4,681 lbs when full at rated specific gravity
- 2" NPT outlet fitting — factory installed and leak-tested
- 1.5" NPT inlet fitting included
- 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
- 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
A 500-gallon water tank is light enough to place by hand yet heavy enough when full — about 4,681 pounds — to punish a careless foundation. The whole job comes down to giving the flat bottom continuous, level support so that two and a quarter tons of water press straight down instead of concentrating on a high spot.
Preparing the Base
Pick a spot that drains, so runoff never undermines the pad. A four-inch bed of compacted crushed gravel or a small concrete slab both work; what matters is that the surface is flat within a quarter inch across the 48-inch diameter and swept clean of stones, roots, and anything that could press a point into the bottom. A poly tank conforms slightly to whatever it sits on, and a single buried rock becomes a permanent stress dimple.
Plumbing the Inlet and Outlet
This tank ships with both the 2-inch outlet and a 1.5-inch inlet, which makes a clean plumbed installation straightforward. Run the supply to the inlet and your draw line off the outlet, and keep the first foot of each connection in flexible hose rather than rigid pipe. Polyethylene expands and contracts with the seasons, and a hard-piped fitting eventually cracks where the wall moves and the steel will not. Add a shutoff valve at the outlet so you can isolate the tank for service.
Venting
Water rushing out must be replaced by air rushing in, or the tank pulls a vacuum and the wall caves. The 16-inch lid is the place to fit a screened breather sized for your fastest draw — a gravity feed barely needs one, but a pump pulling hard can collapse an unvented tank in seconds. The screen keeps insects and debris out of your water while letting the tank breathe.
Maintenance and Long-Term Care
Because this tank holds drinking water, its care is genuine potable maintenance, not just structural housekeeping. The black wall keeps light out and algae down, but sediment still settles and a tank that feeds a household deserves an annual reset.
Seasonal Walk-Around
- Wall and seams: Look for bulging, fading, or weeping at the inlet and outlet a few times a year. A black tank shows chalking before it shows trouble; a bulge means the base has shifted or the tank is overfilled.
- Fittings: Snug the inlet and outlet by hand if they have loosened. Polyethylene relaxes under steady pressure, so check both ports and never reach for a pipe wrench on the plastic threads.
- Lid and vent: Confirm the lid seats fully and the breather screen is clear. An open or torn screen is how contaminants and mosquitoes get into stored drinking water.
Annual Sanitizing
Once a year, drain the tank and flush the sediment from the bottom, then sanitize before refilling. The standard potable dose is a quarter cup of unscented household bleach for every fifteen gallons the tank holds; fill, let the chlorinated water stand for two hours, then drain and rinse until the chlorine smell is gone. This is the same procedure municipal operators use to disinfect a reservoir, scaled to a 500-gallon tank.
Freeze and Sun
In freezing climates, keep the tank turned over so water never sits long enough to ice solid, or drain it for winter — a full tank that freezes can split. Through the warm months the molded-in UV package and the black pigment handle direct sun, but a tank in all-day exposure benefits from a yearly look at its sun-facing side.
Alternatives and Comparisons
Five hundred gallons is a popular size, which means you have real choices to weigh before settling on this upright black tank.
Tall-and-narrow vs. low-and-wide: This 73-inch-tall, 48-inch-wide tank gives you a strong gravity head off the outlet and a small ground footprint, which suits a wall, a pump house, or a tight side yard. If overhead clearance is the constraint instead — under a deck, in a low outbuilding, or on a truck bed — a low-profile or horizontal 500-gallon tank fits where this one will not. For potable supply the upright also drains more completely, since the water column keeps positive pressure on the outlet down to the last few gallons.
Other 500-Gallon Options
Frequently Asked Questions
How long will the 500 Gallon Plastic Water Storage Tank last?
Kept on a sound base and used within its 1.1 SG and 120 F ratings, this tank readily delivers 15 to 20 years. The black UV pigment is the longevity factor for a water tank: it shields the resin from sunlight far better than a translucent wall, and the seamless rotomolded body has no joints to fail. Drain-and-sanitize once a year and it will outlast most of the plumbing attached to it.
What chemicals can I store in this tank?
This is a potable-water tank, FDA approved for drinking water and food-grade liquids, so its first job is clean household, livestock, and irrigation water. It is also rated to 1.1 specific gravity for water-based solutions within that density. It is not built for fuels, solvents, or aggressive industrial chemistry — for those, look at a 1.5-SG liquid-storage tank and check a compatibility chart first.
What kind of foundation does a 500-gallon tank need?
A full 500-gallon tank weighs about 4,681 pounds. That is well within reach of a four-inch compacted gravel pad or a small concrete slab — no engineered foundation is needed at this size. The one rule that cannot be skipped is that the surface be flat and free of rocks, because an uneven base is the leading cause of premature poly-tank failure.
Does this tank come with a warranty?
Yes. Norwesco backs it with a 3-year warranty against defects in materials and workmanship under normal use — molded-in flaws such as pinholes, cracks, and fitting defects. It does not cover damage from a poor foundation, overfilling beyond the rated specific gravity, incompatible chemicals, or impact. Keep your receipt and a photo of the installed tank.
Can I install this tank underground?
No. This is an above-ground tank with vertical walls that are not engineered to resist the inward pressure of surrounding soil; burying it would risk collapse and void the warranty. If you need below-grade water storage, our underground cisterns are ribbed and reinforced specifically for that load.
Buying Considerations
Confirm three things before this 500-gallon tank ships. First, the footprint: it needs a level four-foot circle of firm, drained ground, easy to find but worth checking against fences and downspouts. Second, your fittings — it arrives with the 2-inch outlet and 1.5-inch inlet, so match your hose and pipe to those threads before delivery day. Third, freight: at 94 pounds empty it palletizes for standard LTL, and a lift-gate truck or two helpers can set it without equipment. Listed at $880.00 before freight, quoted to your ZIP.
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