How to Choose a 50 Gallon Water Storage Tank? | Size For Real Use

Guides / By

Choosing a 50-gallon water storage tank starts with matching the tank type to your intended use, then sizing for daily demand and days of reserve.

The right 50-gallon tank depends entirely on whether you need potable storage for emergencies, a pressure tank for a well system, or a water heater. Buying by nominal gallons alone is the most common mistake. A 50-gallon tank that works for one household’s emergency reserve could be useless for a well system with high peak demand. Here is what actually decides the right pick.

Identify the Tank Type Before Sizing

Most search results mix four different product categories under “50-gallon water tank”: storage tanks, pressure tanks, rainwater tanks, and water heaters. Each uses different sizing rules and safety requirements, and you cannot substitute one for another without checking pressure ratings and potable certification.

The critical first check is whether you need a potable water storage tank versus a pressure tank or water heater. A pressure tank maintains system pressure in a well setup and is sized by drawdown, not total gallons. A water heater is sized by hot-water demand and first-hour rating, per Rheem’s guidance. A storage tank simply holds water—either for emergency reserve or for supply at gravity or pump pressure.

What Size Actually Fits Your Household?

That applies to water heaters, not general storage tanks, but it gives a useful baseline for household demand.

Check Dimensions, Weight, and Installation Before Buying

These figures vary by model, so measure your actual installation space. A filled 50-gallon tank weighs over 400 pounds, so it needs solid, level ground with proper foundation support.

Key installation checks:

  • Indoor access: measure doorway and hallway clearances before purchase—many tanks fail to fit around corners.
  • Freeze protection: keep the tank about 85% full if freezing is possible, leaving room for expansion.
  • Shade placement: constant direct sun heats the water and promotes algae; shaded spots are better than ambient heat exposure.
  • Chemical separation: keep plastic tanks away from generators, fuel, or oily surfaces—heat increases chemical leaching risk.

For fittings, confirm your outlet connections match your pump or hose. Common options are 3/4 in NPT or 1.5 in NPT; check the buyer guide before assuming compatibility. Choose food-grade plastic for potable storage, and prefer an opaque or solid color that blocks light and slows algae growth. A large lid or fill opening makes cleaning and refilling far easier, and volume markings printed to resist sun and chemical fading are worth seeking out.

Match the Tank to Pressure and Drawdown for Well Systems

If you are choosing a pressure tank rather than a storage tank, the sizing logic changes completely. ASME guidance requires you to know the maximum drawdown, cut-in pressure, and cut-out pressure before selecting. The Home Depot well tank selection guide says to count the number of water fixtures in the house and choose the closest tank size from its chart.

The smallest tank that meets your required minimum drawdown volume is the correct choice—not the largest one that fits. Oversizing a pressure tank wastes money and can cause short-cycling in the pump system.

For a full comparison of tested 50-gallon storage tank options with prices and capacities, see our roundup of the best 50-gallon water tanks on the market.

Common Mistakes That Sink the Purchase

  • Buying by nominal gallons only without verifying actual use case and reserve time.
  • Ignoring site access and discovering the tank cannot fit through doors or around corners.
  • Overlooking freeze expansion and foundation support—a filled tank is extremely heavy.
  • Using non-potable or uncertified tanks for drinking water; verify potable suitability and compliance documentation first.
  • Confusing water heaters with storage tanks; heater sizing is based on hot-water demand and first-hour rating, not storage-only needs.
Use Case Sizing Criterion 50-Gallon Fit
Emergency potable storage 1 gal/person/day baseline; 50–100 gal/person for self-sufficiency 2 people ≈ 2 weeks (baseline) or 1–2 days (high target)
Storage water heater Household size and first-hour rating Good for 1–2 people; tight for 3–4; undersized for 5+
Well pressure tank Drawdown, cut-in, cut-out pressure Only if drawdown volume matches; check fixture count
Rainwater collection Roof area and rainfall capture goals Works for small systems; verify potable status if used for drinking

What Is the Final Pick?

For emergency drinking water in a two-person household, a 50-gallon potable food-grade tank with a large lid and 3/4 in NPT fittings satisfies roughly two weeks of basic needs. For a well system, skip the storage tank entirely and choose a pressure tank sized by drawdown and fixture count. For a water heater, match the 50-gallon size only if your household is 1–2 people with typical hot-water demand.

FAQs

How long will 50 gallons of water last a family of four?

That is drinking and basic cooking water only. If you also need water for hygiene or pets, plan for a higher per-person figure or add a second tank.

Can I use a regular storage tank for drinking water?

Only if the tank is explicitly labeled food-grade or potable-safe. Look for certification documentation and an opaque or solid color that blocks light. Non-potable tanks may leach chemicals or harbor algae, especially in warm, sunlit locations.

Does a 50-gallon tank need a pump to work?

Not always. Gravity-fed systems work when the tank sits above the point of use. For pressurized household supply, you need either a pump or a pressure tank setup. Check your outlet fittings and matching connections before installing.

References & Sources

Please use a real email you check. If it's fake or mistyped, your message won't reach us and we can't reply — wrong addresses are rejected automatically.