As sea levels rise, a new risk to water quality across the South: septic tanks

As many as a quarter of American homes use a septic system.

By Sarah AschMay 28, 2024 11:41 am,

For all the obvious challenges as sea levels surge and the climate changes, one serious threat to public health and the environment remains largely out of sight: septic tanks.

Millions of septic tanks dot the American South, a region grappling with some of the planet’s fastest rising seas, according to the Washington Post.

Brady Dennis, who covers climate change for the Post, said septic systems need a buffer of dry soil to function properly.

“I think the EPA estimates maybe as many as a quarter or at least 20% of Americans use these systems. And when they’re operating as they should, you have a tank which wastewater goes into,” he said. “The solids sink, and then wastewater goes on into what’s called a drain field, which is usually just a series of perforated pipes that then can slowly allow our wastewater to percolate down through the soil and be treated before it reaches drinking water sources in other waterways.”

As sea levels rise in coastal areas, the groundwater tables get higher as well, which Dennis said can cause issues.

“What can happen is if that buffer that we just talked about becomes too thin, or in some cases nonexistent, the wastewater that is going into the ground is not fully treated or not treated at all before it then floods out into our streets or driveways or our creeks or rivers,” Dennis said. “That can cause some real problems, both for people who were to encounter that water, like in the backyard per se, so as a public health, but more than that just as a water quality worry, as all that makes its way to water bodies.”

On an individual home level, when someone’s septic tank can’t drain properly, it can also cause plumbing problems.

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Dennis said there are a lot of reasons why an area might have a high number of septic tanks.

“In the case of Miami, which is a place that I spent a lot of time for this story, it is obviously an urban, large metropolitan area, but you have a legacy of a time when this place was growing really quickly and there was not the sewer infrastructure to keep up with development,” he said. “And so a lot of septic systems went in.

“If you think about the coastline of the South and the Gulf Coast on around up to the southeast Atlantic coast, there’s also a lot of rural areas. And so it’s not practical in a lot of places to have a centralized sewer system. So a lot of people who don’t live in close proximity to each other rely on septic tanks.”

Dennis said there are a few options to help mitigate the risk of water contamination.

“Both in Miami and other places up and down the coast, you see an effort, wherever possible, that a lot of local governments are trying to get these legacy systems out of the ground,” he said. “That’s the most obvious strategy is to have them not there where they can pollute anymore. That’s obviously an expensive proposition, one that takes a lot of time. It’s not always practical.”

Dennis said it is also possible to upgrade septic systems with new technology that gives homeowners a better idea of when there might be leaks or other problems. And it’s also important to consider development, especially in coastal places, he said.

“Like, where do we allow these to still be put into the ground, and where do maybe local elected officials and whatnot say we’re not going to allow either development in this really vulnerable place, or at least if you are going to build there, you have to hook into like a municipal sewer line,” he said. “So I think those are sort of different levels of strategies that places could undertake to either reduce the risk that’s already there or not introduce new risks.”

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