For locations that are disconnected from the main sewage system, an off-mains solution is crucial to cater to the needs of both visitors and residents. This applies to temporary accommodations like campsites in rural areas as well as a small percentage of homes that are classified as "off grid." It's currently estimated that approximately 5% of all UK homes depend on off-mains solutions.
In this blog post, we’ll explore the various options available in such scenarios, focusing primarily on the most popular choice—sewage treatment plants. We'll discuss how they function, the advantages they offer, how they can be maintained, and the regulations you need to consider before installing one.
Key Takeaways:
- Septic tanks should no longer be discharged into watercourses due to rule changes in 2020. Instead, sewage treatment plants are required if you intend to discharge into a watercourse.
- There are several options for off-mains drainage, including septic tanks, treatment plants, and cesspools.
- Consulting a professional is essential before installing an off-mains drainage system as there are many rules and regulations to follow.
When it comes to managing waste in areas without access to a public sewer, there are three main solutions to choose from:
**Septic Tanks**
Septic tanks are common in the UK, especially for older or remote properties that are off the grid. Typically made of glass-reinforced plastic, these tanks have multiple chambers that allow effluent to separate into liquids and solids. Waste enters the septic tank via the inlet pipe and remains there for a period of time while the liquids and solids separate. Over time, the waste separates into three layers: solids at the bottom, wastewater in the middle, and grease or oils on top. Naturally occurring bacteria inside the tank break down the solids, allowing the liquids to drain safely via a drainage field. The remaining sludge is collected by professionals and removed from the site. Since septic tanks are relatively inexpensive and only need desludging once or twice a year, they are a cost-effective solution for smaller developments with lower waste outputs.
However, if percolation tests indicate that the ground is unsuitable for a soakaway system due to insufficient porosity or lack of space for a drainage field, you’ll need to consider an alternative. UK legislation now prohibits septic tanks from discharging into natural water sources like streams or rivers as of the general binding rules in 2020.
**Cesspools**
Also known as cesspits, cesspools are essentially large sewage holding tanks where waste is fed in from a home or building via underground drainage. Unlike septic tanks, cesspools do not treat waste but simply store it. As a result, they are typically completely sealed for safety, except for a vent to release built-up gases.
While cesspools are the least expensive upfront and easy to install, they require regular emptying by a tanker due to their inability to treat waste. The ongoing cost of sewage collection services can be quite high, potentially reaching thousands of pounds annually, negating the initial savings of the cesspool. Furthermore, cesspools are banned throughout Scotland and are unpopular elsewhere in the UK, often serving as a last resort in locations near drinking water sources where other off-mains solutions are unfeasible.
**Sewage Treatment Plants**
Sewage treatment plants, powered by electricity, are seen as a more modern alternative to septic tanks and come in various types and sizes to suit different budgets and occupancy needs. These plants foster the growth of helpful bacteria that breaks down waste, ensuring it’s clean enough to be discharged into a nearby water source like a river, stream, or reservoir with the appropriate permissions from the Environment Agency. This treatment process significantly reduces sludge buildup, though some sludge still needs to be professionally removed around once per year.
Sewage treatment plants are suitable for a wide range of rural living or working situations requiring off-mains sewage systems, from single properties to large commercial developments.
**How Do Sewage Treatment Plants Work?**
These systems are straightforward in purpose and execution. They clean wastewater from buildings and households not connected to the main sewers through sedimentation, aeration, and disinfection. By treating waste from toilets, showers, baths, kitchen sinks, bathroom sinks, and dishwashers, the cleaned water can be discharged into ecosystems like rivers, reservoirs, or streams.
**Sedimentation**
Wastewater enters the treatment plant and undergoes sedimentation in a primary chamber where gravity helps separate liquid waste from solid waste. The clarified solids, often referred to as sludge, are removed during servicing, while the separated liquid waste moves to the next stage.
**Aeration**
Once liquid waste is separated, it moves to aeration chambers where compressed air increases oxygen levels to promote bacterial growth.
**Disinfection**
The final stage is disinfection where bacteria settles and is removed, leaving the wastewater clean enough to be discharged.
**Advantages of Sewage Treatment Plants**
Sewage treatment plants are increasingly favored due to their numerous benefits:
- **Low Sludge Levels:** Treatment plants generate significantly less sludge than septic tanks, needing emptying just once a year.
- **Eco-Friendly:** They produce a cleaner effluent, around 95% pollutant-free, making them the most environmentally friendly option.
- **Lower Running Costs:** Though initial costs may be higher, they are cheaper to run and maintain due to less frequent emptying.
- **Discharge Options:** Only sewage treatment plants can legally discharge into watercourses in the UK.
**Regulations for Sewage Treatment Plants**
Installing and operating sewage treatment units involves strict rules and regulations:
- **Planning Permission:** Often required for new builds or significant changes, though separate approval may not be necessary for new homes.
- **Legal Compliance:** All plants must be EN 12566-3 2005 certified.
- **Consent to Discharge:** An environmental permit is usually required if discharging into surface waters.
**Installation Advice**
Professional installation is highly recommended due to the complexity and potential impacts of incorrect installations. Proper soil testing, drainage calculations, and electrical connections are critical.
**Choosing an Installation Position**
Considerations include building regulations, odor control, accessibility, noise levels, and gravity-assisted drainage.
**Other Considerations**
Ensure proper drainage pipe depth, outfall, pump requirements, and available electricity. Allow six weeks for full operational readiness.
**Choosing the Right Size**
Select a plant based on property size and expected occupancy, always overestimating to avoid future issues.
**Maintenance**
Regular servicing and emptying are essential. Avoid antibacterial cleaners and ensure proper rainwater protection.
At EasyMerchant, we provide high-quality sewage treatment plants from leading manufacturers, ensuring efficient and eco-friendly solutions. For more information or personalized advice, contact our team today.
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