500 Gallon Water Storage Tank: 550-Gallon Option in 2026
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The short answer
A mid-size tank suits a fixed bulk-water job; check the exact capacity, support and potable-use evidence first.
Last updated October 2026
Our pick
- 1Best horizontal utility option
RomoTech 550-Gallon Tank with Legs- UV-stabilized, BPA-free polyethylene
- Molded gallon and liter marks
- 5.5-inch fill cap and 2-inch side outlet
A 500 gallon water storage tank is a mid-size choice for rain collection, well storage or a utility supply. Five hundred US gallons of water weighs about 4,170 pounds, calculated from USGS density data. The horizontal tank below is a nearby 550-gallon option, so its water load is about 4,587 pounds by the same calculation. Plan around the real capacity and add the tank's own weight.
#1. RomoTech 550-Gallon Tank with Legs: best horizontal utility option
RomoTech 550-Gallon Tank with Legs
Our verdict:
Best horizontal utility option
Best for a bulk utility-water job with room for a low, long tank.
View on Amazon- UV-stabilized, BPA-free polyethylene
- Molded gallon and liter marks
- 5.5-inch fill cap and 2-inch side outlet
Keep in mind: it is a 550-gallon alternative; confirm drinking-water suitability for the exact model.
Product details checked September 2026
The molded level marks help show what is in the tank, and the side outlet gives you a point to connect the drawing line. Confirm the valve and hose parts you need. The legs are part of the tank shape, rather than a reason to skip the base and support checks.
The listing's dimensions are 78 inches long, 48 inches wide and 49 inches high. That gives a body outline of 6.5 by 4 feet, or 26 square feet, by calculation. It is the tank's outline, not a finished pad size. Add room for the outlet, hoses and access to the top fill opening before marking the site.
The same listing gives an empty weight of 160 pounds. Added to the calculated 4,587-pound water load, that is about 4,747 pounds before valves or other parts. Have the maker specify the base and leg support for that load. If you plan to haul it, ask whether this exact model allows your transport use and how it must be secured.
Vertical or horizontal 500 gallon water storage tank
A vertical tank is worth comparing when floor area is the tight constraint. A horizontal model is worth comparing when height is tight. Neither shape removes the need to support the full load. The county rainwater guide calls for a level base that supports a filled tank.
Mark the body on the ground, then add room for hoses, valves and the lid. Check whether a fence or shed roof limits access. An outlet pushed against a wall may look neat on delivery day but be hard to repair later. Compare the vertical water storage tank guide for upright options and the general tank guide for the broader range.
Plan the water source and refill route
Choose this capacity because it matches a job you can describe. A garden reserve needs a collection and use plan. A well reserve needs a dependable refill route. For rainwater, Snohomish County advises considering roof area, water needs and available space when sizing storage. Use local rainfall rather than copying another region's figures.
For household emergency drinking water, the CDC minimum is one gallon per person per day. A mid-size tank can hold much more than a short home reserve, so check whether you can keep it clean and use it on a routine. Smaller jugs can still be useful for water you need to carry during an evacuation.
Plumbing and site preparation
Complete the base before the tank arrives, using the maker's installation instructions. Keep the tank where you can inspect the outlet, fill opening and support. Ask the seller about unloading and placement so a delivery vehicle does not arrive at a site it cannot reach.
For a rain system, Texas A&M AgriLife Extension calls for inlet, outlet, overflow, vent and service openings. Fit screens to keep pests out of vents and overflows. Follow the county guidance on sending overflow away from foundations. A tank that fills during heavy rain needs a safe route for the extra water.
Factors to consider before buying a mid-size tank
We used the listing for the horizontal tank's capacity and fittings, USGS for water weight, and official storage and rain-system guidance. We did not test these by hand. Details come from each listing, so confirm the exact model's use and support instructions before you buy.
For drinking water, the CDC recommends food-grade containers. BPA-free or UV-resistant material alone does not confirm a utility tank is potable. Ask the maker for the exact use rating. The EPA notes bacteria and chemicals in roof runoff, so rain-fed drinking water needs its own treatment and testing plan.
If this class is too small for the refill gap, compare the 1000 gallon tank guide. If it is too much to maintain, the 50 gallon tank guide covers smaller fixed options.
Verdict: 500 gallon water storage tank
A 500 gallon water storage tank fits a measured bulk-water need. The 550-gallon horizontal option is worth a look when height matters, provided the site and intended use suit it. Build the rest of your water reserve with the rain water barrel guide.
Questions people also ask
Is the tank shown exactly 500 gallons?
No. The listed horizontal tank holds 550 gallons. Use that capacity when checking its load and space.
Is a tank with legs ready to place anywhere?
No. Its supports still need a suitable base for the filled load. Follow the maker's installation instructions for the model.