Septic tanks contaminate drinking water by:
I. Using septic tanks in rural areas
II. Rising sea levels near coastline septic tanks
III. Leaks from septic tanks into groundwater
From the question above, options I, II, and III are right.
Septic tanks are watertight containers that allow solid to settle down to the bottom of the container leaving only the less dense liquids to float, making it a strategic water treatment method that enables wastewater used in homes to be treated relying on the action of bacteria to decompose the solid waste.
Septic tanks have a minimal environmental impact as natural filtering takes place in the soil, but they do require some degree of maintenance and attention, as you can't pump wastewater to a water treatment facility.
Using septic tanks in rural areas potentially contaminates the drinking water in that area because rural areas are characterized by not too well-established water systems. Mostly in rural areas, water sources are from wells, rivers, streams, so if a septic tank is too close to a drinking water well, or any drinking water body such as streams, rivers. Water contaminants from the wastewater can end up in drinking water.
Rising sea levels near coastline septic tanks can also potentially contaminate the drinking water in that area because septic tanks are affected by increase in water levels such as the one caused by heavy rainstorms. This occurrence makes it difficult for soil to treat the wastewater from the septic tank before it reaches the groundwater thereby contaminating the drinking water source.
Leaks from septic tanks into groundwater can contaminate the drinking water in that area because if a septic tank is clogged or has a high volume of water, this may saturate the ground with sewer water, so once there is a leakage, it could lead to contamination of any nearby water source because this contamination moves into groundwater, which makes it unfit for drinking due to the pathogenic germs.
In summary, Septic tanks contaminate drinking water when septic tanks are used in rural areas, when there are rising sea levels near coastline septic tanks, and when there are leaks from septic tanks into groundwater.
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