Increased Use Of Septic Tanks Raises Concerns For Environment, Public Health

With millions of people staying at home across the country, domestic sewer systems are becoming more common.

For many Americans, this means increased use of septic tanks. The number of on-site sewage treatment homes in this country has increased, worrying some environmentalists.

In the US, about 25% of people use septic tanks, says Sara Heger, a researcher on the on-site wastewater treatment program at the University of Minnesota’s Water Resources Center. The prevalence of septic tanks varies from state to state, but home builders report the number is increasing, she says.

“We don’t have fabulous data on this because the last time this issue was really raised nationwide was the 1990 census,” she says. “You are planning to add that question back at the moment.”

More and more people are moving further from cities to rural areas and deeper into suburbs that do not have the infrastructure for urban sewage systems. The expansion of the sewer system in rural areas is expensive, says Heger.

Lots of people live within an hour of a big city, and in many cases there’s no way to expand a wastewater treatment plant that far cheaply, she says. In addition, much of the land has already been developed that could easily connect these residents to a facility.

“Very often, treating your wastewater closer to where you collect it is a cheaper option,” she says.

Septic tanks create miniature sewer systems in people’s backyards and the treatment is comparable, she says. With a septic tank, the owner is responsible for the cost and maintenance.

Many older sewage treatment plants do not meet today’s standards, says Heger. These legacy systems can affect surface water or the top layer of a body of water.

In freshwater areas, older systems are leaking phosphorus into lakes, rivers, and streams, she says. In coastal regions, improper treatment of nitrogen from septic tanks could lead to algal blooms. Sewer systems have contributed to blooms on Lake Erie and the Gulf of Mexico in recent years.

Different communities in the U.S. use different methods of tracking sewer systems and management needs, she says.

A sewage system consists of a tank and a floor drain panel that helps treat sewage, she says. These runoff fields are created above the groundwater table, which represents the barrier between a soil surface and the groundwater saturation point.

In different parts of the country, groundwater can be shallow or deep. This makes septic tanks vulnerable to sea level rise, says Heger.

“We develop our systems so that they are even above the shallow groundwater,” she says. “So if the sea level rises and affects the groundwater, it can have a negative impact on the septic tanks.”

Some areas of the United States are underserved when it comes to wastewater treatment, such as the south and Heger’s home state of Minnesota, which has advanced environmental regulations, she says.

Improperly treated wastewater spreads disease, she says, which has brought more attention to wastewater treatment recently.

“We still have communities and even individual homeowners who don’t have adequate wastewater treatment,” she says. “It’s a very big public health problem. It’s not just an environmental issue. “

Chris Bentley produced and edited this interview for broadcast with Peter O’Dowd. Allison Hagan adapted it for the web.

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