Increasing sea levels and more intense storms may result in rising groundwater levels in coastal towns and cities, possibly leading to sewage tanks leaking into homes.

Coastal communities often have their own personal septic tanks to treat waste water, but the surrounding soil must be unsaturated, allowing the waste water to filter out away from the homes and flow into the sea.

According to Phys.org, there are 1 million homes with these types of septic systems in North Carolina alone.

Sea-level rise is one of the anticipated results of climate change, due to increased ocean and air temperatures causing the melting of Arctic and Antarctic glaciers and sea ice.

According to the National Oceanic and Atmospheric Administration (NOAA), the sea level along the U.S. coastline is projected to rise by between 10 and 12 inches in the next 30 years, and between 3.5 and 7 feet by 2100.

This will lead to flooding and storm surges reaching further inland and occurring more frequently, saturating the soil in coastal areas.

Marc F. P. Bierkens, a professor of hydrology at Utrecht University in the Netherlands, told Newsweek: "Sea-level rise will yield to rising groundwater levels. And particularly the rise of sea-level in combination with more severe rainfall events (also a consequence of climate change) is likely to lead to periods in the year when groundwater levels come close to the surface."

The increasingly saturated soil may result in sewage leaking out of the septic tanks.

"This could indeed lead to the flooding of septic tanks. Not only will the septic tank stop working, but if groundwater levels rise to the surface, groundwater that has been in contact with septic tank sewage could end up in people's homes, backyards or on the street," said Bierkens.

"This brings the risk of people coming into contact with highly contaminated water that may lead to diseases such as diarrhea and in the very worst, but much less likely case, dysentery and cholera."

Raw sewage contains a huge number of human pathogens. According to the Indiana Department of Health, exposure to these can lead to contracting campylobacteriosis, cryptosporidiosis, E. coli, stomach flu, hepatitis A, leptospirosis, and even typhoid, among many other diseases.

Coastal communities need to be aware of the risks they could face in the future and prepare accordingly, experts say.

Niko Wanders, an assistant professor of hydrology at Utrecht University, told Newsweek: "The most important thing we need to do is to make sure sewage systems are not leaky and thereby do not affect the groundwater.

"Also, take your drinking water from sources that are of good quality and where potential contamination is not a risk as they are either far from pollution sources, well monitored or where potential leaks in the sewage get a long-enough time to finally reach the well.

"This long period would give the soil time to clean the water, and pathogens are more likely to die," said Wanders.

"For example, in the Netherlands, we use river water that is infiltrated in the sandy dune areas and stays there for a minimum of 120 days before it is used."

Wanders added: "The sand and the treatment after abstraction ensure that all harmful chemicals and pathogens are removed and, as such, it is safe to use the river water, which is not the cleanest source of drinking water."

Bierkens said: "One could install a system of drainage-pumping wells around the septic tank that are temporarily turned on if groundwater levels rise too high.

"This would be a costly solution, though. And, finally, but a very expensive solution to the community as well, is the installation of a centralized sewer system that leads to a water-purification plant."

The increasing sea levels anticipated worldwide will also have a variety of other damaging consequences on coastal communities, including greater levels of storm damage and the salinization of the groundwater.

"This is most likely to occur in communities with a flat topography near the coast," Bierkens said. "Increased sodium content in drinking water is known to be associated with high blood pressures and an increased occurrence of heart failure."

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