A properly functioning septic system will not have a negative impact on the environment. However, if it develops a fault, it could cause major environmental damage. A defective system could contaminate the groundwater in the leach field with harmful bacteria that may then kill nearby wildlife that consumes this liquid.
A malfunctioning septic system that is located close to a body of water, such as a lake, may also harm aquatic life. If nutrients such as phosphorous and nitrogen (both of which are found in abundance in most septic tanks) leak out of the system into the water, they can cause an overgrowth of algae which will consume the lake's oxygen supply. This, in turn, can lead to fish and other aquatic creatures suffocating.
If the lake is used by swimmers, the presence of contaminated water from nearby septic tanks could also result in people developing illnesses such as gastroenteritis and, in extreme cases, cholera.
Here are two ways to minimise the chances of your septic system causing environmental damage:
Minimise the number of loads of laundry you do per week
The anaerobic and aerobic bacteria inside a septic tank help to break down wastewater so that the liquid which then enters the leach field does not contain contaminants that could present a risk to nearby wildlife and plants.
Whilst small amounts of laundry detergent do not usually harm this type of system, excess quantities can reduce the bacterial activity in a septic tank. This, in turn, can affect the level of contamination in the leach field. This is why it is important to reduce the number of laundry loads you do per week and to only use small quantities of laundry detergent in each wash.
Do not be tempted to 'solve' this problem by pumping your laundry wastewater directly into the leach field (and thereby bypassing your septic tank), as this will clog up the soil and cause the field to flood.
Do not use your septic system as a rubbish disposal unit
Putting items into your septic system which it is not designed to handle will almost certainly cause a blockage. If this blockage is large enough, it could cause a pipe to burst open. This could then result in contaminated wastewater seeping into the nearby soil, lakes and rivers.
As such, it is crucial to be conscious of what you put into your toilets and drains. Things like nappies, feminine hygiene products, food wrappers (however small they might be) and any other items that have the potential to clog your pipes should never be thrown into your drainage system.