Hillsborough County Septic Permits and the Two-Basin Rule

Which septic rules apply to your Hillsborough County property depends on which way your land drains. The county sits across two river basins, and each one has its own state-adopted cleanup plan. Only one of them carries the nitrogen requirements that make a new or replacement system expensive.

Two Basins, Two Different Plans

Florida cleans up impaired waterways through Basin Management Action Plans, or BMAPs. A BMAP is written for a watershed, not for a county, so its boundary follows the land rather than the county line. Hillsborough contains parts of two of them, adopted sixteen years apart, for two different pollutants.

The practical effect is that two homeowners a few miles apart, both in unincorporated Hillsborough County, both replacing a failed drainfield, can face different rules. That is not a loophole or an oversight. It is how the statute is written.

If Your Property Drains to the Alafia

The Alafia River Basin BMAP covers more than 270,000 acres across Hillsborough and Polk counties. DEP verified the river as impaired for nutrients, dissolved oxygen and fecal coliform, which makes it a nutrient BMAP. An updated plan was published in draft form on March 26, 2025.

Inside a nutrient BMAP, section 403.067 of the Florida Statutes does the work. Since July 1, 2023 a new conventional septic system is prohibited on a lot of one acre or less where central sewer is available. Where sewer is not available, the owner must install a DEP-approved enhanced nutrient-reducing system that achieves 65 percent nitrogen reduction.

Two more rules follow from the same section. An existing system owner must connect to sewer within 365 days of written notification from the utility that connection is available. And DEP states that on repair or replacement, an existing system inside a priority focus area must be upgraded to an enhanced nutrient-reducing system unless the applicant can show that sewer will be available within five years.

If Your Property Drains to the Hillsborough River

The Hillsborough River BMAP was adopted on June 30, 2009 and it addresses fecal coliform bacteria. It is not a nutrient plan. It contains no priority focus area and no onsite sewage remediation plan, so none of the nitrogen-reduction machinery described above applies here.

That does not mean septic systems go unmentioned. The plan identifies likely bacteria sources as, in its words, systems in low-lying, older residential communities with unmounted septic system drainfields. At the same time, the county health department assessment recorded in the plan did not identify any high-probability areas for septic system failure within most of the waterbody segments studied.

Lake Thonotosassa sits in this basin, draining through Flint Creek toward the Hillsborough River, as does Blackwater Creek. So a Thonotosassa homeowner is outside the nitrogen rules but inside a basin where failing drainfields are already named as a suspected bacteria source. Different pollutant, different plan, same advice: a drainfield that is failing is a problem regardless of which map you are on.

Getting a Permit in Hillsborough County

Septic permitting in Hillsborough is handled by Environmental Health Services at the Florida Department of Health in Hillsborough County. Seventeen Florida counties were moved to DEP permitting after the 2021 transfer of the onsite sewage program. Hillsborough was not one of them.

The office is on the second floor of the Main Health Department and is open 8am to 4pm, closing from noon to 12:30 for lunch. The phone number is 813-307-8059 and the fax is 813-272-7242. Applications are accepted by hand delivery, mail, fax or email, and separate packages exist for new construction, existing system modification, repair, abandonment and holding tanks. Recent permit and inspection records can be looked up through the e-Bridge system.

The rule chapter to look for is Chapter 62-6, Florida Administrative Code. If a page tells you Hillsborough septic systems are governed by Chapter 64E-6, that page is out of date: 64E-6 was the Department of Health chapter before the 2021 transfer of the onsite sewage program to DEP. Our Florida septic regulations page walks through what changed, and the county permit index shows which of the 67 counties permit through DEP rather than a health department.

Septic to Sewer: Where the County Is Already Building

Hillsborough County runs a countywide, multiyear program converting septic properties to central sewer, using conventional gravity sewer and low-pressure systems. It is a real capital program with named target areas, which is worth knowing if your neighborhood is on the list. A property scheduled for conversion is a poor candidate for a costly new drainfield.

For the University Area program specifically, the county states that all application and connection costs are free to the residential property owner. For multifamily properties the county covers construction while residents pay the City of Tampa application and impact fees. In every case, a connected property starts receiving a monthly water bill that varies with usage.

Those terms are stated for the University Area. Do not assume they carry across to Gibsonton, Palm River, Ruskin or Wimauma. The county program pages do not state whether connection is mandatory, what happens to the abandoned tank, or a completion date. On the question of whether you must connect, the answer comes from the statute rather than the program: section 403.067 gives you 365 days from written notice by the utility.

What It Costs

We will be straight with you about the permit fee, because most pages will not be. Hillsborough County does not publish its septic permit fee schedule online. DEP says plainly that your county health department determines the total permitting fee. So the only reliable number is the one you get by calling 813-307-8059, and we would rather tell you that than print a figure we cannot stand behind.

If you are weighing a repair against a replacement, the basin question matters financially. In the Alafia basin a replacement may trigger the enhanced nutrient-reducing standard, unless you can show sewer is coming within five years. In the Hillsborough River basin that trigger does not exist today.