Editor's note: information that appeared in an earlier version referencing Briarcliffe Acres has been updated.

Brown and rainbow-colored sewage bubbled up from the Folly Beach sands after Tropical Storm Irma. Newcomer beachfront resident Matt Napier couldn't believe his eyes.

"My girlfriends and I didn't swim or walk barefoot on the beach until April," he said. That was five months later.

But beachside septic tanks are no surprise to longtime beach property owners. Hundreds, if not thousands, of them are buried in the dunes up and down the coast, the leach fields underground sometimes draining the effluent toward the ocean.

They are a legacy of the camp and beach cottage days of the coast, a make-do time when people hauled old cabooses to Folly to use as cabins.

They are also trouble waiting for the next storm to happen.

Uncovered septic tanks littered Edisto Beach oceanfront properties, with the leach fields washed away, after Hurricane Matthew in 2016. Hurricane Irene in 2011 uncovered the septic tank and washed out the leach field at Folly Beach County Park.

The problem isn't confined to those beaches or to South Carolina.

The S.C. Department of Heath and Environmental Control estimates that anywhere from 10 percent to 30 percent of more than 1 million septic systems in the state aren't working safely, and the federal Environmental Protection Agency estimates anywhere from 10 percent to 20 percent nationwide.

Nearly every beach home on Folly has a septic tank and field, nearly every one on Edisto Beach does, too. A third or more on Isle of Palms have them. A lot of not-so-developed beaches do, as well. The Grand Strand beach towns have largely moved to public sewer, but there are still a few septic systems up there.

The Natural Resources Defense Council in a recent State of the Beaches report cited leaky septics as a leading cause of beach water contamination.

Pony up?

Septic systems are underground set-ups that hold sewage in an anaerobic, or oxygen-free, tank so material can sink and decompose, while the somewhat cleaned-up effluent seeps to an adjacent "septic field," or leach field. The decomposed material must periodically be pumped from the tank.

More recently, as storm tides and heavier vacation use have strained the septics, town after town has mulled moving to public sewer systems instead.

The trouble with doing that, though, also quickly bubbles the surface. The cost is in the millions and the sewer lines come with fees that a lot of owners simply aren't willing to pay. Why pony up to install the line then get hit with a monthly charge when septic is free until you need to pump it out?

"You want to not get elected on Folly Beach, talk sewer," Mayor Tim Goodwin said.

The Isle of Palms Planning Commission in 2017 studied extending its system and forcing owners to tie in — noting the pollution problems septics cause. The cost estimated was $52 million. The report also noted that previous attempts by the city to make this move ran into "significant resistance from residents on the island."

The city is now studying options for upgrading sewer service in phases but the council has taken no specific action.

After Matthew, Edisto Beach looked at expanding sewer to beachfront residents, but couldn't get enough of them to agree on the move to qualify for a bond to do it, said Town Administrator Iris Hill.

'Super beach'

There hasn't been a lot of stink about beach septics simply because the problem usually gets diluted in the ocean. State regulators who monitor beach water quality for contamination suspend that testing after tropical systems. Later testing usually doesn't find enough pollution to close the beach to swimming.

Most beach closings in South Carolina tend to be short term after rainstorms leak fecal waste from yards or streets into the water. The last time Goodwin can recall a portion of Folly Beach closed to swimming because of bacterial pollution, the culprit turned out to be a dead pelican in the water, he said.

But the concern is large enough on Folly that taking a look at further regulation of septics is one of the management priorities that led to a six month beach building moratorium passed in May.

Folly Beach has a particular issue with septics because an exemption from state law allows construction on the "super beach," literally in dunes that only are there after a renourishment and tend to be overwashed by storm tide during the years between renourishments.

Those homes also have tended to install smaller systems because of limited space. The properties also are a hot spot of development on the island. The city had one permit approved and others in the wings when it declared the moratorium.

Private septic pump-out companies do a regular business on the island.

"You have problems with people trying to overload the system. We're working on that," Goodwin said.

'Ecologically safe'

You'd think the S.C. Department of Health and Environmental Control would be all over this issue. But the septic and beach water quality regulator stays mostly hands off.

DHEC has called for no swimming at beaches where septics have been a chronic problem. It warned against swimming in a swash, or run of ocean water on a beach in front of the Briarcliffe Acres community near Myrtle Beach after an Horry County study indicated high fecal levels likely were due to contamination from septic systems in the community.

The town has now connected all occupied homes in the flood plain to a sewer system, said Mayor Huston Huffman and Myrtle Beach public works officials.

“Although we still see high pollution numbers in the swash after heavy rains, I can state categorically that this is not due to septic tanks in the flood plain area of Briarcliffe Acres,” Huffman said.

After Matthew, the town of Edisto Beach urged DHEC to force beach property owners to move their septic fields as far inland as possible before reissuing the permits for them, but DHEC didn't.

"When properly installed and maintained, a septic system can render wastewater ecologically safe," said DHEC spokesman Tommy Crosby. "DHEC is not working with or directing beach towns with septics to move to sewer."

Napier said the problem of septics gurgling up will get worse as Folly develops and will overcome owner resistance to hooking on to sewer. He would do it now, he said.

Folly officials aren't convinced. Sewer systems fail, too, said City Administrator Spencer Wetmore.  A rupture in the line in nearby Hollywood closed down the oyster beds behind Folly Beach earlier this year. 

If a storm knocks out electricity, generators are needed to power a sewer system. By and large, the septics keep working, Goodwin said.

The only way he could see Folly Beach going all out for sewer tie-ons is if the state ordered it, he said.

Reach Bo Petersen Reporter at Facebook, @bopete on Twitter or 1-843-937-5744.

Science and environment reporter. Author of Washing Our Hands in the Clouds.