Nobody likes to think about what happens after they flush the toilet.

But that out-of-sight-out-of-mind waste can cause serious problems to Florida’s environmentally fragile waterways.

A lot of the people who have been thinking about the problem think the state needs to flush its septic systems — about 2.6 million septic systems that serve about a third of the state’s population and discharge about 426 million gallons of wastewater a day — and hook them up to sewer systems.

In February, Gov. Ron DeSantis awarded $240 million through the state Department of Environmental Protection for 36 projects to upgrade wastewater treatment and eliminate nearly 20,000 septic systems.

And DeSantis’ proposed budget for fiscal year 2023-24 includes $200 million for the wastewater grant program, including septic-to-sewer projects.

But is the costly process of switching from septic to sewer worth the money?

No doubt, making the switch would help protect Florida’s waterways. But when it comes to nutrient pollution — the nitrogen and phosphorus that feed toxic algae blooms in water bodies including Lake Okeechobee and the St. Lucie and Caloosahatchee rivers — septic systems aren’t the state’s biggest polluters.

That ignoble distinction goes to farming.

State data cited in a recent VoteWater.org “Deep Dive” showed agriculture is a “principal” source of nutrient pollution in at least half of the state’s watersheds. 

And septic systems don’t cause the harmful algal blooms that periodically plague the St. Lucie and Caloosahatchee estuaries. The reason we know: Septic systems are out there operating 365 days a year, and the blooms ravage the estuaries only when there are Lake Okeechobee discharges.

So as big a problem as septic systems are, they’re at best playing for second place.

Also, some septic systems are water polluters and others aren’t. The key to finding the polluters is like the key to selling real estate: Location, location, location.

Keep away from water

A 2022 study by the Harbor Branch Oceanographic Institute found that “Florida’s coastal regions are particularly vulnerable to pollution from septic systems because of shallow water table and porous soils.” 

Here’s why:

Septic systems are made up of an underground tank, which separates and stores solid waste, and a drain field, which spreads out liquid waste just under the ground surface so that it percolates into the soil. The soil acts as a filter and does a good job removing bacteria and viruses. 

But even properly functioning septic systems remove only about 30% of the wastewater’s nitrogen and 60% of its phosphorus, nutrients that are the reason the grass is always greener over the drain field and that feed harmful algal blooms.

The study in Lee County also noted that nitrogen isotopes in coastal red tides “closely matched” those in septic system discharges, “pointing to human waste as a driver of the worsening harmful algal blooms.”

In other words, septic system outflows don’t cause massive algae blooms — but they feed them.

Researchers at Harbor Branch, a division of Florida Atlantic University, suggested that the state’s coastal areas with lots of canals and high densities of septic systems be prioritized for septic-to-sewer projects.

By the way, the six counties along the Indian River Lagoon have more than 300,000 septic systems and account for more than half the area’s wastewater disposal, according to an earlier Harbor Branch study.

Septic-to-sewer success story

The city of Port St. Lucie has been following the experts’ advice, and with significant results. 

Since 1999, Port St. Lucie has replaced more than 10,000 septic systems (10,072 as of Feb. 28) with connections to the municipal sewer system. The effort has focused on the “old city” — if you can call a city that’s been around since only the 1950s “old” — with aging septic systems and in five “hot spots” where septic systems are close to waterways that drain into the North Fork of the St. Lucie River, a tributary of the Indian River Lagoon.

The city estimates the conversions have kept about 2,546,000 pounds of nitrogen and phosphorus out of the ground, the river and the lagoon.

Looked at another way, the conversions will continue to prevent 61,942 pounds of nitrogen from entering waterways each year, an amount that will grow as the city continues its conversion program. (Nearly 14,000 septic systems remain in the city, more than 4,000 of them within 50 feet of waterways; and city laws prohibit building houses or businesses with septic systems if connections to sewer lines are available.)

Protecting springs

But problems with septic systems aren’t confined to the coasts.

Florida has more “first magnitude” springs — those that produce 64.5 million gallons of water a day or more — than any other state. All are fed by groundwater, and septic systems near springs “contribute hundreds of thousands of pounds of nitrogen to the groundwater each year,” according to the Florida Department of Health.

Septic systems contribute about 42% of the nitrogen pollution in Southwest Florida’s five largest springs, according to the Southwest Florida Water Management District, and about 29% of the nitrates in Orange County’s springs, according to Orange County Utilities.

For that reason, the Florida Springs and Aquifer Protection Act prohibits septic systems on lots smaller than an acre near any “outstanding Florida spring,” making developments near springs another focus of septic-to-sewer conversions.

Limiting septic systems to large lots is a good rule of thumb throughout the state.

Sewers better, but not perfect

Florida has about 2,000 wastewater treatment facilities that treat a total of 1.5 billion gallons of sewage from homes and businesses each day. Another 2,100 plants treat industrial sewage. 

For instance, high inflows from Hurricane Ian last September caused Brevard County’s South Beaches sewage treatment plant to spill more than 7.2 million gallons of what the county called “highly treated” sewage into the Indian River Lagoon. 

Most of the treated sewage is released into waterways (subject to federal Clean Water Act standards) or pumped into deep injection wells. Some is treated to remove all bacteria and pathogens to produce fertilizer known as Class AA biosolids, Some is partially treated — Class B biosolids — and spread (or dumped) on farmland.

What to do with sludge from sewage treatment plants, as well as the stuff that has to be pumped periodically from septic tanks, is another issue for another “Deep Dive.”

Sewage treatment plants do a good job, but they aren’t infallible. Septic system proponents like to note that leaks and failures can occur; and when they do, because the plants treat so much sewage, the results can be massive.

Show me the money

Back to the issue of money, which is where this discussion started:

According to a DEP “white paper,” installing a septic system typically costs from $3,000 to $6,000, with enhanced systems designed to remove more nitrogen costing from $10,000 to $15,000.

Connecting to a sewer system, the DEP says, costs from $2,500 to $20,000.

The reason for the wide range of costs: Varying ways of hooking up to the sewer system. Building conventional gravity-powered sewer lines with pump stations is the most expensive; grinder systems — named for the small electric motors installed at each house to grind up sewage and send it through small, easy-to-install lines — are much less expensive.

In Port St. Lucie, for example, homeowners pay $6,026, plus $122.50 for deposit and filing fees, to be fitted with grinder systems. Those in the targeted “hot spot” areas can apply to have that cost cut in half, thanks to grants from the city, DEP and the Indian River Council.

And that’s where the government grants come in — because it’s deemed to be in the public’s – and taxpayers’ — best interest to switch as many septic systems as possible to sewers … as long as they’re in the proper location, location, location.

Getting political

Increased funding for septic-to-sewer conversions statewide will surely deliver benefits. But anyone thinking this will solve our water quality problems should temper their expectations.

In fact, conversions can become a political issue, as Florida’s powerful sugar industry and its proxies seek to divert attention away from industry pollution and suggest the main culprit for algae blooms is homegrown, from local septic tanks.

This won’t and mustn’t derail septic-to-sewer conversions in areas where toxic algae has been a problem. But the conversions can’t be hailed as “the solution,” and then used as a rationale to ignore other, more significant sources of pollution.