Septic Tanks: A Hidden Water Pollution Source?

Septic tanks are a common wastewater treatment system for many households, especially in rural areas. However, they can pose a risk of polluting both groundwater and surface water sources if not properly maintained or situated. This is because septic tanks rely on the surrounding soil to act as a natural filter for the wastewater they treat. If the soil is permeable or the water table is high, wastewater can escape into the surrounding environment before it is adequately treated, contaminating water sources with harmful bacteria, viruses, and nutrients. This can lead to serious health issues, including gastrointestinal illness, rashes, skin and eye infections, and flu-like symptoms.

Poorly treated wastewater can cause blue baby syndrome in infants

Septic tanks can pollute water through groundwater and stormwater runoff. Even when functioning properly, septic tanks can contaminate water sources. This is particularly true in areas with certain types of geology, such as South Florida, where the bedrock is porous and the soil is sandy. This means liquids can flow through the ground very easily, and wastewater from septic tanks can move too quickly through the natural filters, resulting in more contamination reaching groundwater.

In coastal areas, septic systems are a significant contributor to water pollution. They are often situated close to the beach or surface waterways, and their wastewater contains high levels of nitrogen and some phosphorus. This wastewater eventually reaches the groundwater and flows downstream towards surface waters, such as lakes and streams, and ultimately the ocean. High levels of nitrogen in waterways have severe impacts on coastal ecosystems, causing algae blooms that deplete the water of oxygen, leading to mass die-offs of aquatic life.

In addition to the environmental impacts, poorly treated wastewater from septic systems can also have direct human health consequences. One example of this is blue baby syndrome, a condition where a baby's skin turns blue due to a decreased amount of hemoglobin in the blood, which is responsible for carrying oxygen around the body. This condition is often caused by water contaminated with nitrates, which is most common in drinking water in farming communities that use well water due to the use of fertilizers and manure. When infants consume formula made with nitrate-rich water, their bodies convert the nitrates into nitrites, which bind to hemoglobin, forming methemoglobin, which is unable to carry oxygen.

To prevent blue baby syndrome, it is essential to avoid giving infants water from wells until they are at least one year old. Boiling water does not remove nitrates, so other sources of water should be used for infant formula. It is also important to limit the amount of nitrate-rich foods fed to babies, such as broccoli, spinach, beets, and carrots, until they are at least seven months old. If blue baby syndrome is suspected, a doctor may request a blood test for diagnosis and determine the appropriate treatment, which may include medication or surgery.

Septic tanks can contaminate drinking water wells

Septic tanks that are not regularly serviced and pumped can become clogged with solids, causing sewage to back up into homes or surface in yards. This untreated wastewater contains harmful bacteria, viruses, and nutrients that can be dangerous to human health if they come into contact with drinking water. It is important for homeowners to properly treat wastewater and maintain a safe distance between their septic systems and drinking water wells.

In addition to bacterial and viral contaminants, household products such as fertilizers, soaps, and detergents can also contribute to water pollution if a septic system fails. These products contain phosphorus and nitrogen, which can cause nutrient pollution and act as fertilizers in surface water. This can lead to excessive algae growth, reducing water quality, killing aquatic life, and introducing toxins.

To prevent septic system pollution, most jurisdictions have legislation mandating a minimum distance between septic tanks and drinking water wells. Proper design and construction of septic systems are also crucial, taking into account soil characteristics and the need for grease interceptors in certain cases. Regular maintenance, such as pumping the tank and avoiding harmful products, is essential to prevent system failure and protect drinking water sources.

By following guidelines, regulations, and proper maintenance procedures, homeowners can help ensure that their septic systems do not contaminate drinking water wells, protecting both their health and the environment.

Septic tanks can cause stormwater runoff pollution

Most storm drains do not have filtration systems and flow directly into canals, waterways, bays, and other coastal waters. This means that flooding in areas with septic tanks can result in serious pollution problems. The contaminated wastewater can contain bacteria, viruses, and parasites that can make people sick with gastrointestinal symptoms, rashes, skin and eye infections, flu-like symptoms, and more.

Additionally, sewage discharges can pollute waterways with excess nutrients, leading to harmful algal blooms that put human health at risk and result in fish kills and coral reef die-offs. These algal blooms can also smother coral reefs in tropical regions, causing them to fail. The excess nutrients can also cause an increase in harmful algae blooms that produce toxins, further contaminating shellfish and causing fish kills and other sea life deaths.

To prevent stormwater runoff pollution from septic tanks, it is important to ensure that the septic system is properly maintained and situated at an appropriate distance from water sources. Upgrading to advanced septic systems that can remove a significant amount of nitrogen from wastewater and have shallower drain fields better suited for high water table areas is also recommended.

Septic tanks can cause sewage spills and infrastructure failures

Sewage Spills

Lack of Routine Maintenance

Septic tanks require routine maintenance, such as pumping out the tank every three to five years and regular inspections for leaks or cracks. Neglecting maintenance can lead to accumulations of scum, sludge, and hard water, eventually creating blockages and system failure.

Overloading the System

Septic tanks have a limited capacity for wastewater. Excessive water usage, leaky faucets, or inefficient appliances can lead to overloading, causing the tank to overflow.

Flushing the Wrong Substances

Septic tanks are designed to handle human waste and biodegradable toilet paper. Non-biodegradable items, such as diapers, paper towels, or sanitary products, can cause clogs. Additionally, excessive use of disinfectants and chemical cleaners can disrupt the balance of beneficial bacteria, reducing the tank's effectiveness.

Poor Soil or High Water Table

Septic systems require suitable soil conditions and water table depth. In areas with poor soil or a high water table, the system may fail, resulting in sewage backups and contamination.

Infrastructure Failures

Improper Design and Construction

Improperly designed and constructed septic systems often fail due to inadequate sizing, installation in impermeable soils, or improper construction techniques. Inadequate separation distances from water sources or buildings can also contribute to early failure.

Flooding and High Water Tables

Flooding and high water tables can cause septic tanks and drain fields to become flooded, leading to overflows and backups. Contaminated wastewater can then runoff into nearby storm drains or back up into pipes on the property.

To prevent these issues, regular maintenance and proper design and construction of septic systems are crucial. Additionally, managing stormwater effectively and ensuring sufficient separation between the drain field and groundwater can help reduce the risk of infrastructure failures and sewage spills.

Septic tanks can contaminate groundwater

However, if the drain field is overloaded with too much liquid or clogged with solids, it can become flooded, causing sewage to back up into the home or surface in the yard. This is one way that septic tanks can contaminate groundwater, as the untreated wastewater can contain harmful bacteria, viruses, and nutrients that can make people sick if they come into contact with drinking water sources.

Another way that septic tanks can contaminate groundwater is through stormwater runoff. When septic tanks and drain fields become flooded due to high water table levels, substantial rainfall, or high tides, they can overflow. This can cause contaminated wastewater to run off into nearby storm drains or back up into pipes, potentially reaching canals, waterways, and coastal waters.

In addition, the design and construction of the septic system can also play a role in groundwater contamination. For example, if the system is not properly designed for the specific soil conditions, the wastewater may not be adequately treated before it reaches the groundwater. Poor construction can also lead to cracks in the septic tank, allowing effluent to leak out and contaminate groundwater.

Furthermore, the maintenance of the septic system is crucial in preventing groundwater contamination. Neglecting regular servicing and pumping of the tank can lead to sludge buildup, which can force wastewater out of the tank prematurely and clog the drain field. This can result in untreated wastewater reaching the groundwater and potentially impacting drinking water sources.

To prevent septic tanks from contaminating groundwater, it is essential to follow guidelines on the minimum distance between the tank and drinking water wells, ensure proper maintenance and servicing, and avoid using products that can harm the bacteria in the tank that are crucial for treating wastewater.

Frequently asked questions