- Septic tank systems function independently and are ideal for rural or remote homes. A connection to mains drainage depends on the available infrastructure and is most common for urban properties.
- Septic tank system owners are responsible for all maintenance and repairs, while mains drainage system users pay regular fees to their local water and sewage company.
- Routine inspections and maintenance are more important for septic tank systems, due to the risk of pollution or expensive system failure. For mains drainage there is less of a requirement.
- Installation and running costs vary hugely. Septic tank systems typically have greater initial costs and lower ongoing costs, whereas mains drainage connections have a fixed monthly cost.
- Environmental and health impacts rely on proper maintenance, and both types of system need to comply with local standards to protect water quality and the environment.
- When deciding on a septic tank versus mains drainage connection, you’ll want to consider the potential costs and the suitability of the local area – some rural properties are not close enough to a main sewer to be able to connect to it.
Septic tank systems and sewer systems both handle household wastewater, but operate in very different ways. Septic tank systems and other off mains drainage systems treat wastewater at source. Mains drainage systems, operated by local water and sewerage companies, transport wastewater to communal treatment facilities. So deciding between a septic tank system or a connection to a main sewer really comes down to a number of factors such as where you live, installation and maintenance costs, and how much of a maintenance routine you want to take on yourself. Some homeowners prefer the freedom of a septic tank, while others prefer the simplicity of a mains drainage connection. To help weigh up the pros and cons, here’s a breakdown of both systems.
How Each System Works
Understanding how septic tank systems and mains drainage systems operate is crucial when evaluating their suitability for your needs. Both systems manage household waste, but their configuration, method, and level of autonomy differ.
The Self-Contained Septic Tank System
A septic tank system operates as a self-contained, on-site unit. Wastewater from taps, toilets and showers flows into the septic tank. Once in the septic tank, the wastewater separates solids from liquids – the solids sink into sludge at the bottom and oils rise to the surface.
In the middle sits the separated wastewater, which leaves the tank for the drain field or soakaway system. As a network of slotted or perforated pipes, the drainage field allows water to seep into the ground, which filters out the final remnants of toxins. It’s a critical step which a clogged drainage field can prevent, posing health or environmental risks.
Septic tank systems deal with a limited amount of water per day, depending on their size, so they can suit individual houses or small communities. They operate without mains drainage pipes, making them a popular option among rural communities or areas without access to more urban services. Routine emptying and maintenance is the responsibility of any property owners who connect in to the septic tank system.
The Mains Drainage Connection
Mains drainage or sewers can connect thousands of homes and buildings by way of a system of underground pipes. Wastewater from each property flows into the mains sewers via smaller pipes from each property. This network usually depends on gravity, but sewage pumping stations can be used to assist waste that needs to travel over hills or long distances.
Pumping stations propel the collected waste to a central treatment plant. Here, sophisticated processes purify and extract pollutants from water before it is discharged or reused.
Unlike septic tank systems, mains drainage sewer systems rely on maintenance and repair by the local water and sewerage company responsible. As a network of pipes connecting many properties, this means that a single failure or blockage can disrupt the drainage of many properties at the same time.
Operational Process: Step-By-Step
- Wastewater exits the house either going to a septic tank or into the public sewer.
- In septic tank systems, waste separates in the tank, bacteria breaks it down, and separated water moves to the drain field for percolation.
- In mains drainage sewer systems, waste travels through underground pipes, sometimes with pumping stations, to a treatment plant.
- Treated water is returned to the environment either onsite (when a property has a septic tank) or centrally (when a property is connected to a main sewer).
Septic vs. Sewer: The Key Differences
Both septic tank systems and mains drainage sewer systems function differently and have their own requirements. Understanding these differences enables homeowners to select the most suitable wastewater management systems.
Ownership
- Septic tank: The homeowner owns and is responsible for the system in all regards.
- Mains drainage sewer system: The water and sewerage company owns and manages the system.
- Septic tank: The owner pays for repairs, emptying, and inspections.
- Sewer: The user pays monthly utility bills for the provision of drainage services.
Septic tank systems become the homeowner’s responsibility for everything from maintenance to repairs, which provides direct control over the system but also can represent a long-term investment and commitment. Conversely, mains drainage sewer users rely on public sewer systems, paying bills for ongoing care while repairs and upgrades fall under local water and sewerage company’s responsibilities. Septic tank owners must schedule regular maintenance, whereas properties connected to the mains drainage sewer system have little control or ownership of any repairs that may be necessary.
Maintenance
Septic tanks require regular emptying by a local tanker operator. If this is not carried out, or is not done regularly, the entire system can become blocked which if left unchecked can lead to system failure. This can be both expensive and detrimental to the environment. Maintenance is essential for the safety and effectiveness of the system.
Property owners connected to mains drainage sewers users have very little maintenance responsibility for pipes beyond the boundary of their property.
Reliability
Septic tank systems frequently function well in remote sites, and if well maintained they can provide many years of reliable use. Mains drainage systems, although typically reliable, can suffer failures from old piping, heavy rainfall or blockages. These issues can impact entire communities all at once and any repairs necessary may not be carried out quickly by the water and sewerage company.
When a septic tank has a problem, the action is on the homeowner, which may be fast if assistance is at hand. Mains drainage sewage problems tend to take longer to resolve because repairs rely on available resources and other priorities.
Location
Urban homes tend to be linked to mains drainage sewer systems, where these exist in dense networks. In rural or remote areas, a septic tank system (or other off mains drainage system) is generally the only option because there is no main sewer near enough to connect to.
Longevity
A well-maintained septic tank system can last for decades, particularly if well installed and maintained. While mains drainage sewer systems might have a longer lifespan, they can require costly improvements if pipes start to corrode or break.
Financial Implications
Septic tank systems and public sewer systems both have specific financial obligations that can affect homeowners long term.
Installation Costs
- Septic tank systems: these types of systems and installation can often cost in excess of £10,000 – the cost is affected by soil quality, system size, permits, and excavation work required.
- Sewer systems: Connection fees are generally lower, but only if a main sewer pipe is close enough to connect to – laying the pipework required to join a main sewer can quickly become cost prohibitive.
- Percolation tests are a must for septic tank systems with a drainage field or soakaway system – unfavourable ground can increase the size and cost of the system required.
- In the long run, for rural properties not yet connected to a main drainage sewer, a septic system can be cheaper because running a public sewer can be massively cost-prohibitive or even impossible in remote areas.
Property Value
It’s important to note that a well maintained and efficiently functioning septic tank system should add value to your property, and that it is important to be able to evidence this should you come to sell your home. You can do this by firstly following all emptying and maintenance advice, and documenting this as you go, and secondly by arranging a home-sellers survey when you start to think about selling your property.
In urban areas, a connection to the mains drainage is assumed and checked as part of the sale process.
Environmental & Health Considerations
Septic tank and public sewer systems are both critical wastewater management systems, and can have negative impacts on the local environment if they are not properly maintained and repaired when needed. Specifically, there are legal requirements of an owner of a property with a septic tank system to ensure that it does not cause any pollution of the local environment.
- Septic tank systems allow separated waste water to percolate through the soil. If they aren’t properly maintained, they can contaminate subsoils and groundwater.
- Sewers transport waste to treatment plants, where sophisticated techniques eliminate pollutants before water is discharged appropriately. This minimises the risk of soil or groundwater contamination. Large sewer networks can disrupt local areas due to blockages or leakages through broken pipes which can in turn pollute the local environment.
- Septic tanks in disrepair can release bacteria and toxins into the environment. Sewers, if neglected, can overflow in cities, distributing waste and causing unpleasant odours. Both systems require maintenance and oversight to mitigate potential risks to public health.
Resource Use
Septic tank systems rely on natural bacterial action, requiring no energy input for transport, making them an eco-friendly option in rural areas. Conversely, mains drainage sewer systems require more energy and resources due to a reliance on pumps.
Safety Risks
Septic tank failures can pose safety threats by polluting the local ground and potentially backing up to the property, while main sewer blockages can cause an overflow of sewage onto local streets and roads, posing an obvious health risk.
The Myth of “Fit and Forget”
Many believe that once a septic tank system is installed, it runs itself with little assistance. Unfortunately, this is rarely the case. Septic tank systems require maintenance over time in order to stay safe for the environment and functional. Without regular emptying and close observation, pipes can become clogged, tanks can fill with sludge, and waste may pollute the ground. This poses health risks and can contaminate the surrounding area and watercourse.
Regular checks are essential for effective wastewater management systems. Experts recommend tanks be emptied on a regular basis, typically annually, although this can vary according to tank size and the number of occupants in the house. For example, a family of five living in a property with a small septic tank will need frequent emptying than a single occupant in a property with a large tank. It is always advisable to ask the tank emptying operator if they can observe the tank whilst it is being emptied, and advise you of any particular damage or defects that you wouldn’t usually see above ground. You can also request a specialist to carry out a septic tank inspection at the same time – get in touch with our team today, who would be happy to arrange this for you.
If you don’t empty a septic tank regularly enough, this can lead to a build-up of solids and your pipes becoming blocked. This causes wastewater to back up into the house or overflow into the garden, and can result in expensive repairs. In the worst case scenario, the entire system might need replacing, which can cost thousands of pounds.
Don’t let out of sight mean out of mind. Small issues such as a blocked pipe or a leak can turn into major problems if ignored. A small crack in the tank can allow untreated waste to leak into the soil, polluting the local environment. This may not be limited to a local problem; contaminated water can kill local wildlife, highlighting the importance of proper septic tank maintenance.
Homeowners should know what to look out for. Simple habits, such as not flushing wipes or harsh chemicals and minimising water usage, keep the system functioning well for longer.
Making Your Decision
Choosing between a septic tank system and a mains drainage sewer connection comes down to the location of your property and its proximity to sewers, cost and local regulations. Each system serves different purposes, and it pays to consider each option on its own.
Your Property
Soil type is important. Some soils, such as sandy or loamy soils, drain well and are ideal for septic tank systems that include a drainage field or soakaway system. Clay-heavy soils, on the other hand, are often unsuitable – they retain water, have reduced percolation ability and this can lead to septic tank issues. A larger area available at the property allows for more space for a drainage field, which is necessary for most septic tank systems. If the space is not available, or the soil type is not appropriate, there can be other off mains drainage systems that can be suitable. If space is prohibitive, and a mains sewer system is located nearby, a sewer system connection could be the answer.
If your land floods or remains soggy after rainfall, a septic tank system with a drainage field may not function properly. Testing the soil with a percolation test and consulting local ground information prevents expensive errors.
Your Mindset
Maintenance, in the form of regular emptying and observation, is a constant requirement with a septic tank system. But there is full autonomy when something goes wrong, and you can quickly act to remedy problems. A mains drainage sewer system connection translates to less hands-on work, but you have less influence on service or price. Repairs can take a long time to be carried out, creating waste overflows or unpleasant smells for longer than the property owners may want to tolerate.
Both systems require you to be mindful of the environment. Septic tank systems, when properly maintained, can be more efficient with resources. They require less infrastructure and process waste on site – although poor maintenance and care can risk contamination of the local environment. Main sewer systems are operated by water and sewerage companies, and more energy and resources are typically consumed.
Conclusion
Septic tank system vs. mains drainage sewer system: Which is best?
Septic tanks suit rural homes, provide some self-autonomy but also require regular maintenance. Sewers connect to a larger network, suit urban properties, and usually represent less work for the consumer. Costs can fluctuate either way, from installation to repairs.
There are many factors than affect whether a septic tank or a mains drainage connection is best – the available space at your property; the proximity of the property to a main sewer connection; the type of soil at the property; the investment available and views on energy and resources.
For advice with your decision, speak to a local specialist who can help you weigh up the specific options at your property – call our team today who can arrange an engineer to visit your property and advise you accordingly.
Frequently Asked Questions
What is the main difference between a septic tank system and a sewer system?
A septic tank system manages wastewater on-site, typically in rural areas, while a mains drainage sewer system transports effluent to a central sewage treatment plant, common in urban areas.
Which system is usually more cost-effective in the long run?
Septic tank systems typically have higher upfront costs, but when properly maintained, they can lead to savings over time, contrasting with the ongoing expenses associated with mains drainage sewer systems.
Is a septic tank system better for the environment?
This depends entirely on the owners of the property. A well-kept septic tank system can be eco-friendly, while poor maintenance can lead to contamination and environmental impact.
Do septic tank systems need regular maintenance?
Indeed, a septic tank system requires regular emptying, appropriate for the property, and ongoing observation to identify any problems and remedy them before they can escalate.
Can I choose between a septic tank and a mains drainage sewer system?
The choice depends on a number of factors – mostly, where you live and local infrastructure. In populated areas, public sewer systems are typically available, while rural homes commonly rely on septic tank systems.
