In order to conserve water and reduce wastewater pollution, many green home designs now include options for septic tank treatment of wastewater from household toilets, kitchens and laundry rooms. These range from traditional solid tanks with pumps and leachfields, to more modern closed systems that treat the wastewater inside the septic system, releasing much cleaner wastewater into the ground. Learn more below about the various septic tank options available today.
Traditional Septic Systems
A traditional septic tank system includes a large concrete holding tank, with an entry pipe that accepts wastewater from the household. In the tank, gravity divides the wastewater into liquid and solid waste, and then pumps the liquid waste out into a leachfield. The leachfield consists of a bed of crushed stones and tile, which removes more wastewater solids. The water then travels through shallow trenches where soil bacteria further purifies it. Eventually the wastewater, considerably cleaned of toxins, makes its way into the water table.
Problems with Traditional Septic Systems
Solid waste can accumulate in any part of a traditional system, causing blockage and waste backup into the home. One-piece septic tanks should be pumped out every 3 years to prevent clogging and backup. A mound located above ground level is the access point for the septic tank pumping truck. Large septic tanks are made in 2 pieces, and have a central seam. Frequently this seam will develop leaks, allowing untreated solid waste to seep directly into the soil and hence to the groundwater. Traditional septic systems work best when used with as many low-water consumption devices as possible, including low-flow toilets and shower heads, and water-conserving washing machines and dishwashers.
Other Septic Tank Models
More up-to-date septic systems comprise a much smaller solid waste tank, often made out of durable plastic instead of concrete, and a multi-pipe separation system that drains off much higher volumes of liquid waste, moving it to the leachfield more quickly. These have several capped mounds above ground for access.
Newest Septic Tank Models
The newest septic tank systems employ a small tank along with a system of five or more large-diameter flexible pipes that can actually treat the wastewater and decontaminate it intensively before releasing it into the soil. The leachfield is composed of a fine-grained sand instead of stones, that draws out much higher volumes of contaminants than a conventional stone and trench leachfield. The gravity feed of the system eliminates the need for pumps and electricity. The pipelines can be installed on a 25% slope, greatly assisting with gravity feed of liquid waste. The pipes themselves are made of recycled plastic to further reduce the footprint of this septic system on the environment. On small sites that handle large volumes of wastewater, these systems can be installed one above another, helping speed up the flow of waste through the system, and minimizing the ground area occupied by septic treatment.
Septic tank systems, whether traditional or modern, implement a key feature of green home design - localized waste treatment. They will continue to play a key role in sustainable living in the future.