Water management is a cornerstone of sustainable construction. Whether you’re embarking on a self-build or overseeing a large-scale development, understanding the intricacies of drainage systems is paramount. Let’s dive into the world of mains drainage and on-site drainage, examining their pros, cons, and applications.
Understanding Drainage Systems
Drainage systems are intricate networks designed to manage both foul water and rainwater or surface runoff. Internally, a myriad of small waste pipes from sinks, basins, showers, and toilets converges into a soil stack. This stack then channels the waste either towards public sewers or an on-site tank.
Above-ground waste pipes, known as soil and vent systems, are typically installed by plumbers. These systems need proper venting above roof level to prevent foul odors from permeating the house. Below ground these networks, managed by groundworkers, connect to either mains drainage or on-site systems.
Mains Drainages
Mains drainage is typically overseen by a district’s water company. Connecting to this system often involves accessing main drains, usually located under streets. While this can be a costly endeavor especially if roadworks are required, it’s often more economical than on-site alternatives.
However, challenges arise when the main drains are located at a higher elevation than the site. In such cases, a lifting station equipped with a macerator pump becomes necessary. This system collects waste and pumps it uphill into the mains drainage.
On-site Drainage: An Alternative.
For those in rural areas or those facing prohibitive mains connection costs, on-site drainage systems like septic tanks or sewage treatment plants are viable alternatives. These systems however require land and regulatory permissions. Below are some of the onsite options;
– Cesspit: A basic tank with no outlets, typically emptied periodically by a lorry which makes it less economical.
– Septic Tank: Separates solids from liquids with the latter flowing into a drainage field. The solids would have to be emptied but this happens way less than in cesspits. Modern installations however adhere to higher environmental standards.
– Sewage Treatment Plant: Electrically powered systems that treat waste more effectively than septic tanks, producing cleaner liquid waste.
– Reed Bed: Often part of a sewage treatment setup, especially in areas with poor soil drainage. Bacteria within the reed bed digest sewage and purify the water.
Cost Implications
On-site drainage systems, while offering autonomy, come with their own set of costs. Initial installation can hover around £15,000, with ongoing costs for maintenance, tank emptying, and electricity for certain models.
Managing Surface Water
Rainwater, unlike foul water, doesn’t require treatment. It can be directed into underground soakaways or nearby watercourses. Modern regulations necessitate thorough assessments to ensure adequate drainage capacity, preventing flooding during severe storms. Additionally, permeable paving might be mandated to mitigate flash flooding.
Rainwater Harvesting: A Sustainable Approach
Instead of merely directing rainwater into soakaways, one can harness it for household use through rainwater harvesting. This system involves collecting rainwater in an underground tank, filtering it, and then using it for non-potable purposes like flushing toilets, laundry, and gardening.
Conclusion
Whether you opt for mains drainage or an on-site system, understanding the intricacies of each is crucial. While mains drainage offers convenience, on-site systems provide more autonomy. Regardless of the choice, ensuring effective water management is key to a sustainable, eco-friendly future.