What Size Septic Tank Do I Need? Florida Requirements by Home Size

In Florida, septic tank size is dictated by law — not guesswork. The Florida Administrative Code (64E-6) sets minimum tank capacities based on the number of bedrooms in your home, with additional requirements if you have a garbage disposal. Getting the size wrong means either failing a permit inspection or overloading a tank that's too small, leading to premature failure and expensive repairs. Here's exactly what you need to know.

Florida Minimum Septic Tank Sizes (FL Admin Code 64E-6)

Florida determines required tank size by bedroom count, not by the number of occupants. The logic: bedrooms represent the maximum potential occupancy of the home. If you have a garbage disposal, the state requires a larger tank because disposals add significant solid waste volume.

For homes with more than six bedrooms, add 150 gallons per additional bedroom (or 150 gallons plus the garbage disposal increment). These are minimums — going larger is always allowed and often recommended, especially for households with high water usage. For the full regulatory framework, see our guide to Florida septic tank regulations.

How to Determine Your Current Tank Size

If you're not sure what size tank you have, there are several ways to find out:

• Check your septic permit — Contact your county health department. They keep records of every permitted septic installation, including tank size, type, and installation date.
• Measure the tank — If you can access the tank lids, measure the distance between them. A 1,000-gallon concrete tank is typically about 5 feet wide × 8 feet long. A 1,500-gallon tank runs about 5 feet × 10 feet.
• Ask during your next pumping — Your septic pumper can measure the tank during service and give you exact dimensions and capacity.
• Check your home inspection report — If you had a septic inspection before buying, the report should include tank size.
• Look at your property records — Some counties include septic details in property appraiser records, accessible online.

Signs Your Tank Is Too Small

An undersized tank fills up faster than the bacteria can break down solids, leading to premature drain field failure. Watch for these warning signs:

• Frequent pumping needed — If you're pumping more than every 2 years with normal water usage, your tank may be too small for your household.
• Persistent slow drains — Multiple slow drains throughout the house (not just one fixture) suggest the tank can't keep up with demand.
• Recurring backups — Sewage backing up into the lowest drains, especially after heavy water use days (laundry day, guests visiting).
• Drain field stress — Soggy areas, odors, or unusually green grass over the drain field indicate solids are reaching the field because the tank can't hold them long enough for treatment.

If your home has been expanded — bedrooms added, a mother-in-law suite built — your original tank may no longer meet code requirements. This is common in growing Florida communities around Orlando and Jacksonville where homeowners add living space without considering septic capacity.

Upgrading Your Septic Tank Size

Replacing an undersized tank with a larger one typically costs $3,000 to $7,000 in Florida, depending on the new tank size, material, accessibility, and local permitting fees. The process involves obtaining a permit from your county health department, excavating the old tank, installing the new one, and connecting it to existing plumbing and the drain field. Accessibility is a major cost factor — if the old tank is under a deck, driveway, or mature landscaping, excavation costs rise significantly. Plan for 2–5 days from start to finish for a straightforward swap.

New Installation Costs in Florida

If you're building new or need a complete system replacement, here's what to budget:

Florida's high water table — especially in South and Central Florida — often requires advanced systems that cost more than conventional gravity-fed setups. Your county health department determines what type of system your property requires based on soil testing and site evaluation. For more on pricing, see our septic cost guide.

Factors Beyond Bedrooms That Affect Sizing

While Florida code uses bedrooms as the baseline, real-world performance depends on several additional factors:

• Number of occupants — A three-bedroom home with six residents produces far more waste than one with two. Consider going one size up.
• Daily water usage — The average person uses 80–100 gallons per day. High-use households (long showers, frequent laundry, irrigation tied to septic) should size up.
• Garbage disposal — Disposals increase solid waste volume by 30–50%, which is why Florida code requires a larger tank when one is installed.
• Water softener — Salt-based water softeners discharge brine into the septic system, which can disrupt the biological process and add volume. Some experts recommend upsizing the tank by 10–15% if you use one.
• Hot tub or jacuzzi — Draining a 400-gallon hot tub into the septic system creates a massive volume spike. Consider routing hot tub drains away from the septic system.

Common Florida Tank Materials

The material your tank is made of affects lifespan, cost, and maintenance requirements:

Concrete tanks are by far the most popular choice in Florida due to their weight (which resists flotation in high-water-table areas) and longevity. Fiberglass is a growing alternative in areas where access is limited, since the lighter weight simplifies installation. For a full maintenance plan based on your tank type, see our septic tank maintenance schedule.

Frequently Asked Questions

What is the minimum septic tank size in Florida?

The minimum septic tank size in Florida is 900 gallons for homes with 1–3 bedrooms (without a garbage disposal). With a garbage disposal, the minimum increases to 1,050 gallons. These minimums are set by Florida Administrative Code 64E-6 and enforced by county health departments.

Can I install a septic tank larger than the minimum required?

Yes, and it's often recommended. A larger tank provides more treatment time for waste, reduces pumping frequency, and handles usage spikes better. The additional cost for going one size up is typically $200–$500 for the tank itself — a small investment that pays off in reduced maintenance over the system's lifetime.

How much does it cost to replace a septic tank in Florida?

Tank replacement alone costs $3,000–$7,000 depending on size and accessibility. A full system replacement (tank + drain field) ranges from $5,000–$15,000 for conventional systems and $15,000–$30,000 for advanced systems required in areas with high water tables or poor soil conditions.

Does adding a bedroom require a larger septic tank?

Potentially, yes. If adding a bedroom pushes your home past a size threshold (e.g., from 3 to 4 bedrooms), Florida code requires a larger tank. You'll need a permit modification from the county health department, and if your current tank doesn't meet the new minimum, it must be upgraded before or during the renovation.