Choosing a water storage tank comes down to matching four things to your situation: how much the tank holds, what it's made of, what shape it is, and whether it sits above ground or gets buried. All four come down to three questions about your water: what you're storing, where the tank will sit, and how you'll draw the water out. At Tank Supply Direct, this is the conversation we have with callers every day. Our first question is always what the tank is for, and once we know that, the size, material, and shape usually follow on their own.
What Size Water Storage Tank Do I Need?
The right size comes from two numbers: how much water you use in a day, and how many days you want to go between refills. Multiply the two and you have your tank size. A tank much bigger than that number costs more to ship, needs a bigger base, and may not fit through your gate, so choose the size that covers the days of supply you actually want, not the biggest tank you can afford. Fire reserve tanks are the one case where you don't work out the size yourself, because local fire code sets that capacity and your fire marshal or insurer will tell you the number. For everything else, these planning figures are the ones we use on the phone.
| What you're storing water for | Planning figure | Where the number comes from |
|---|---|---|
| Whole-house supply on a well | About 82 gallons per person per day | EPA WaterSense |
| Emergency drinking and basic needs | 1 gallon per person per day, for as many days as you want to cover; needs can double in hot weather | Ready.gov |
| Rainwater collection | About 0.62 gallons per square foot of roof per inch of rain | Texas A&M AgriLife Extension |
| Beef cattle | 12 to 15 gallons per head per day; lactating dairy cows up to 40 | University of Maine Extension |
| Horses | 10 to 12 gallons per head per day, up to about 22 for a working horse in 95-degree heat | University of Maine Extension and NDSU Extension |
| Sheep and goats | About 2 to 4 gallons per head per day | University of Maine Extension |
| Construction, dust control, or hauling | Enough for the most water you need to carry or use at one time | Our rule of thumb |
Here's how the math works for a household. Say a family of four on a well wants three days of water on hand in case the pump fails. Four people times 82 gallons is 328 gallons a day. Three days of that is 984 gallons, so a 1,000-gallon tank covers it. If they want a week of supply instead, the number is about 2,300 gallons, and a 2,500-gallon tank is the fit.
Livestock works the same way: multiply the number of animals by the high end of the per-head figure, then by the days you want between refills. For rainwater, multiply your roof's square feet by 0.62 to get the gallons one inch of rain delivers. Then compare that number to how much water you use between rains, and size the tank to hold the smaller of the two.
Plan for your hottest week rather than an average day. People and animals drink much more in heat. Ready.gov notes that emergency water needs can double in hot climates, and cattle and horses can drink roughly twice as much in summer as they do in mild weather. If your household uses more in summer, with outdoor watering or more people at home, run the math with your own summer number. When the result lands close to a tank size, the next size up is the safer buy.
The weight of the water also limits how big you can go. Water weighs about 8.34 pounds per gallon, so a full 1,000-gallon tank weighs about 8,340 pounds. That weight decides what the tank can sit on.
Which Water Tank Material Is Best?
Most residential and farm water tanks are polyethylene, which is a rigid plastic. Steel is the other common choice. Fiberglass and concrete are the other two materials you'll come across, so they're in the comparison too, even though we sell poly and steel.
| Material | Typical cost | Lifespan and durability | Best uses | Watch-outs |
|---|---|---|---|---|
| Polyethylene (poly) | Low | Built for outdoor use when made with UV-stabilized resin. Unprotected poly can show sun damage in as little as 5 to 8 years | General water storage, drinking or non-drinking, for homes, farms, and small businesses | Don't put a tank without UV stabilization in full sun. Clear or translucent walls let algae grow |
| Steel (galvanized or stainless) | Medium. Stainless costs more than galvanized | Galvanized tanks are manufacturer-rated for 20 to 30 years. Rust is what eventually wears them out | Rainwater, ranch and ag water, drinking water when the tank is lined | Rust, and larger tanks need equipment to move and set. Plain steel must be lined for drinking water, and drinking-water compliance differs by product, so check the listing |
| Fiberglass | Medium to high. Under about 1,000 gallons, fiberglass is expensive for what it holds | Durable and fairly easy to repair | Mid to large sizes where you want a rust-proof alternative to steel | Price at small sizes; footing prep |
| Concrete or masonry | Depends on the job. Concrete tanks are cast on site or set in place as a precast unit | Durable, but can crack and leak over time, especially underground in clay soil | Large, permanent, in-ground or site-built tanks | Cracking and leaking; can't be moved later |
Sources for the table: the cost tiers and the fiberglass and concrete notes come from the Texas Water Development Board's rainwater harvesting manual. The galvanized steel lifespan is from Texas Metal Tanks' galvanized tank listing.
Most homes and small operations end up with a poly tank, and poly listings use a few terms that need a plain explanation.
What the Grade and Rating on a Poly Listing Mean
HDPE is the standard grade of poly, and it's what nearly every rigid water tank is made from. XLPE is a tougher, more expensive grade made for chemicals and liquids heavier than water, so a water tank doesn't need it. The specific gravity rating says how heavy a liquid the tank can hold compared to water. Water is 1.0, and a standard poly water tank is rated around 1.5, so water is well within its limit. We regularly talk people out of buying a water tank for fertilizer or chemicals, because a water tank is built for water and nothing heavier.
Why Color and Sun Matter
The color of the tank decides whether algae can grow inside it. Sunlight feeds algae, so a dark or opaque tank keeps the inside dark and keeps algae from growing. Don't buy a clear or translucent tank for water storage. Sun also wears on the plastic itself, so outdoor poly tanks are made with UV-stabilized resin. For a specific lifespan number on the tank you're considering, read the warranty on its listing. Every product on our site carries its manufacturer's warranty.
Which Tank Shape Do I Need?
- Vertical tanks stand upright and hold the most water for the ground they take up, so they're the standard choice for a tank that stays in one place. They're filled after they're set and aren't meant to be moved with water in them. You'll find them in the vertical water tanks collection.
- Horizontal leg tanks lie on their side on molded legs. They're built for hauling and transport, as long as the tank is properly supported and strapped down. If the tank rides on a trailer or truck bed, this is the shape. You'll find them in the horizontal water tanks collection.
- Cone bottom and open top tanks come up for mixing and process work far more than for storing water, so most water buyers can skip them.
- Small portable and stackable tanks hold from 35 gallons (the Rockwell Exodus) to 250 gallons (the Rockwell QuakeTank). They're the usual choice for an emergency reserve kept indoors, in a garage, closet, or utility room. You'll find them in the emergency water storage tanks collection.
Above Ground or Underground?
Most people set the tank above ground. It costs less, it's easy to inspect for leaks and settling, and if it sits uphill from where you use the water, gravity can move the water for you. The downside is that an above-ground tank is out in the weather. It takes sun all summer and can freeze in winter, so color and freeze protection both matter more than they would for a buried tank. Water expands by about 9 percent when it freezes, so in a cold climate you bury the tank below the frost line, insulate it, drain it before winter, or keep the water moving.
Burying the tank protects it from freezing and keeps it out of your yard, but it takes a tank built for burial. The tank has to be listed for direct burial, because soil presses on the walls, and groundwater in wet soil can push an empty tank upward. Gravity can't lift water up out of the ground, so a buried tank needs a pump to bring the water up. It also needs a riser, which is a neck that comes up to ground level so you can open the lid. Read the product's install guide for its burial depth and water table limits, and check your local rules before you buy. Our below-ground tanks are in the rainwater harvesting tanks collection.
Can I Drink From a Water Storage Tank?
Only if the tank is meant for drinking water, and only if your local rules allow it. Tanks meant for drinking water are called potable tanks, and two designations show up on their listings. NSF/ANSI 61 is a standard from NSF, a public health testing organization. A tank that meets it has been tested to make sure it doesn't leach harmful contaminants into the drinking water it touches. FDA-compliant resin means each ingredient in the plastic is allowed for food contact under FDA rules.
Neither designation on its own makes a tank legal for drinking water where you live. Requirements for drinking water and rainwater vary by state, county, and utility, so check the compliance details on the specific product listing, then check your local requirements before you buy. Our potable water tanks collection groups the tanks that carry drinking-water designations, and every listing shows its own details.
A Storage Tank Is Not a Pressure Tank
A storage tank is a holding tank. It isn't built to hold the pressure a well pump or a city water line pushes through your pipes. Put a storage tank under line pressure and it will eventually fail.
Jonathan Saucedo on our team took a call from a homeowner on a 50 to 60 PSI well system who was about to order a 500-gallon cistern and plumb it into the line to hold pressurized water for his house. Jonathan explained that the tank wasn't rated for pressure and would fail over time, then walked him through the setup that works. The well fills a holding tank, a float control tells the well pump when to refill it, and a separate pump moves water from the holding tank to the house.
What to Check on the Listing Before You Buy
- Capacity and exact dimensions. Check the diameter and height against your gate, your base, and anything overhead, and confirm the capacity matches your sizing math. The tank needs a level base that carries its full weight, either compacted ground or a paved slab.
- Color and UV protection. For a tank that will sit outdoors, look for UV-stabilized resin in the specifications and choose a dark or opaque color.
- Fitting sizes and positions. Where the outlet sits and what size it is decides how you connect to the tank, so make sure it matches your hose or pipe.
- Specific gravity rating. For water, 1.5 is plenty. Anything heavier than water needs a higher rating.
- Compliance details. If you'll drink from it, read the potable designations on that specific listing and check your state and local requirements.
- Ship-from location. Every product on our site shows where it ships from, and that location drives the freight cost.
- Lead time. In-stock orders ship within 5 business days. If a tank is made to order, ask us for the lead time before you buy.
How Much Does a Water Storage Tank Cost?
Four things set the price: how much the tank holds, what it's made of, whether it carries drinking-water designations, and its shape. These are real prices from our catalog as of September 2026:
- 35-gallon Rockwell Exodus emergency tank: $250
- 250-gallon Rockwell QuakeTank: $1,150
- 500-gallon Custom Roto-Molding vertical poly tank: $669.41
- 1,000-gallon Custom Roto-Molding vertical tank: $731.43
- 2,500-gallon Quadel vertical tank: $1,799.99
The 250-gallon QuakeTank costs more than the 500-gallon vertical tank because it's a compact emergency reserve tank. A compact emergency tank costs more per gallon than a plain vertical tank. Steel runs well above poly at a similar size. A 1,480-gallon galvanized steel cistern from Texas Metal Tanks lists at $4,139.99, and a 1,200-gallon stainless steel cistern from the same maker lists at $5,319.99. Availability on steel tanks changes, so check the listing for current price and stock.
Then add freight. The larger tanks ship on a freight truck, and the freight is part of the real cost. We show the ship-from location on every product, and we will not ship the order or charge any additional freight without your approval, so you know the delivered cost before we ship.
How Your Tank Gets Delivered
Your tank ships LTL freight to the curb, and the carrier calls you first to schedule a delivery appointment. Getting the tank off the truck and over to its base is up to you, so have help or equipment ready. If you have no way to lower a heavy tank off the truck, ask us about liftgate service. A liftgate is a platform on the back of the truck that lowers the freight to the ground. It adds to the freight cost.
When the truck arrives, inspect the tank with the driver present. Look at every side. The driver will ask you to sign the Bill of Lading, which is the delivery paperwork. Before you sign it, photograph anything that looks damaged and write the damage on the Bill of Lading. If you sign a clean Bill of Lading and find damage afterward, the freight claim can be denied. Report any damage to us within 48 hours of delivery.
Tell Us What You're Storing
If you're still weighing two sizes or two materials, call us at 833-465-8265. Tell us what you're storing, where the tank will sit, and how you'll use the water, and we'll help you pick the right tank, or tell you plainly if the one you're looking at won't work. You can also browse our water storage tanks collection and filter by material, capacity, and specific gravity to narrow the list to the tanks that fit your setup.