When you install or replace a well system, one of the most important components is the pressure tank. It’s also one of the most misunderstood. Choosing the wrong size tank—especially an undersized one—can lead to weak water pressure, pump burnout, and higher long-term costs. Here’s what homeowners need to know about tank sizing and why it matters for your well system.
What Size Well Tank Do I Need?
1. What Determines the Correct Tank Size?
The key factor in tank sizing is your well pump’s gallons per minute (GPM) output. Florida plumbing code requires that your tank provides at least one gallon of usable water (“drawdown”) for every GPM your pump produces. That means if you have a 20 GPM system, your tank needs to deliver at least 20 gallons of drawdown.
Pressure tanks don’t store their full labeled size as usable water. A tank’s drawdown capacity depends on its size and pressure settings. For most Florida homes with a 20 GPM pump, the tank that meets the required drawdown is a 65-gallon pressure tank. Smaller tanks—even those labeled 44 gallons—don’t provide enough usable water to meet code or protect your pump.
| # of Bathrooms | 1 | 1-1 1/2 | 2-2 1/2 | 3-4 | 5-6 |
| Minimum Pump Size (gpm) | 7 | 10 | 14 | 17 | 21 |
2. What Happens When the Tank Is Too Small?
An undersized tank causes your pump to switch on and off constantly, a problem known as short cycling. This wears down the pump fast and can lead to early failure. You may also notice:
- Fluctuating water pressure
- Air spurting from faucets
- Dirty or cloudy water due to stirred-up sediment
- Higher electric bills because your pump is running too often
Over time, the cost of repairing or replacing a pump far outweighs the small savings from installing a smaller tank. That’s why proper tank sizing isn’t optional—it’s essential.
3. How to Make Sure Your Tank Meets Florida Code
The simplest way to confirm your tank is correctly sized is to match it to your pump’s GPM. For the standard 20 GPM system most homeowners use, the proper tank size is a 65-gallon unit. This size provides the right amount of drawdown at typical 40/60 PSI pressure settings.
A larger tank also reduces strain on your pump, keeps your pressure steady, and extends the overall life of your system. Choosing a tank that meets code protects both your equipment and your wallet.
At Spring Hill Well Drilling, we size every tank according to Florida requirements and manufacturer specifications. No shortcuts, no undersized systems, and no surprises later. If you’re unsure whether your tank is the right size—or if you think your system may be short cycling—we’re here to help.
Contact Spring Hill Well Drilling Today!
If you’re interested in learning more about the advantages of having a well in Florida, contact Spring Hill Well Drilling today. Our experienced team can answer your questions and guide you through the process of exploring this cost-effective and independent water solution.
CONTACT USAdditional Resources:
National Ground Water Association: https://www.ngwa.org/
Florida Geological Survey: https://floridadep.gov/fgs
Proper Tank Sizing: Why Your Well System Needs the Right-Sized Pressure Tank
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