How Septic Tank Maintenance Protects Your Local Waterways
18 August 2025 by CSG
Have you ever wondered how having off-mains drainage can impact your local rivers and lakes?
Across the UK, there are properties that are disconnected from the mains sewer system. Instead of using the public sewage system, these properties use private ‘off-mains’ alternatives. These are: cesspits, septic tanks, and sewage treatments plants. When working well, these systems aren’t a cause for concern. But when something goes wrong wildlife, watercourses and people can be put at risk.
Why do our waterways matter?
England’s rivers are one of our country’s most important natural features. Not only do they help make Britain a picturesque place to live and explore, but they also help us protect against flooding. They also provide fresh water for both drinking and farming.
Some of our most beautiful rivers are ‘chalk streams’. Their pure water from underground chalk aquifers and springs make them perfect sources of clean water. They are also ideal for lots of wild creatures to breed and thrive. We’re lucky because the majority of the world’s chalk streams are found in England.
But far too many of our waterways have been overused and undervalued. Drained almost dry in places and polluted in others. Less than a fifth of England’s rivers are healthy. Private sewage systems (especially ones that are not well maintained) do play their part in this.
How do sewage systems affect water quality?
When sewage makes news headlines, it’s usually in the form of a ‘overflow event’. The pictures show dirty water pouring from a pipe into a river, or beaches are declared unsafe for swimming. But these events do not tell the full story of sewage and the way it can affect our environment.
Across the UK, many properties are not connected to the mains sewer system. This might be because the existing pipes are too far away or cannot be extended to the property’s location.
These properties instead rely on private ‘off-mains’ cesspits, septic tanks and small sewage treatment plants. When these septic systems are in full working order and have been installed correctly, they offer a practical solution to an important problem. But when something goes wrong, the environmental impact can be shocking.
The kinds of issues found in faulty or mismanaged off-mains systems cause something called ‘chronic pollution‘. In contrast to a pollution incident, this happens over a long period and isn’t always immediately obvious. An under-performing system may slowly leak waste or release pollutants with its discharged wastewater.
This means that whilst the percentage of off-mains properties is small, they can have an outsized impact on their local aquatic environments. This is compounded by the fact that people will often have systems in clusters – sometimes entire villages.
Signs your tank requires maintenance
Being aware of the signs of an unhealthy system can help you protect your local waterways. Every system is different, but some common signs to look out for is:
- Check for unpleasant odours of sewage or a ‘rotten egg’ smell around your system or even in your basement or cellar.
- Check for pooling of wastewater or muddy ground surrounding your sewage system.
- Check how your drains are behaving. Slow flushing toilets or toilets that are overflowing, gurgling in the drains, overflow at washing machine hookup and overflow into shower or bath when emptying sinks might all be signs of an unhealthy system.
- Check if the ground has movement or dips near the sewage system or drainfield.
- Check if nearby water streams or ditches have effluent in them.
If you’d like more information on how to take care of your sewage system, take a look at our Septic Tank Care Do’s & Don’ts blog here!
How does septic tank maintenance help to protect rivers and lakes?
When your septic tank is in good working order, it efficiently treats your household wastewater without causing harm. But when regular maintenance is neglected, the consequences can literally spill over into our rivers, lakes, and water supply.
One aspect of routine maintenance that can often be overlooked are regular inspections of your tank and the surrounding area. Cracks in your tank, blocked pipes or signs of wear can go unchecked for years before a leak causes visible damage or environmental contamination. Professional inspections every 1-3 years can help to identify problems before they get worse.
Regular septic tank emptying can also help to prevent tank overflows. Over time, solids build up in your tank. If not regularly emptied, they can overflow into your drainage field. This causes multiple issues including clogging the soil and allowing untreated wastewater to seep into nearby ditches, streams and even drinking water sources.
British Water and the Environment Agency recommends that you empty your tank annually. By doing so you reduce the risk of pollution escaping into the environment.
If you have a septic tank or sewage treatment plant, your system will rely on naturally occurring bacteria to break down waste. But harsh chemicals like bleach, disinfectants and drain cleaners can kill these beneficial bacteria. This can disrupt the treatment process. Choosing environmentally friendly products helps to maintain a healthy balance inside the tank.
Local resources and community impact
Protecting local rivers and lakes isn’t just the job of large organisations. It starts with everyday choices made by people like you.
Across the UK, organisations like the Environment Agency, local river trusts, and wildlife charities work to monitor water quality and reduce pollution. Lots of these companies offer advice and support on how to manage your wastewater responsibly.
CSG also provides expert services for septic tank maintenance, repairs, and replacements. These are all designed to help you stay compliant with the General Binding Rules and reduce the risk of pollution.
Useful links:
So, to recap…
It’s easy to overlook what’s underground, but your sewage system plays a key role in the health of your local environment. A system in good working order protects rivers and lakes from untreated wastewater and harmful bacteria. But when neglected, it can contribute to pollution that affects wildlife and the wellbeing of your community.
The good news? Regular care makes all the difference.
By properly maintaining your septic tank, you’re not just preventing costly repairs. You’re actively protecting the environment and helping preserve clean water for future generations.
