Shared Septic Systems - 12/10/2004 - House Systems Plumbing Septics Wells

Shared Septic Systems

Shared septic systems are an affordable, space-saving solution to wastewater treatment most appropriate for sites with some of the following characteristics: failed conventional absorption fields, narrow or oddly-shaped lots, high water table, high bedrock, low soil percolation and especially situations where a group of seasonal homes will be converted to full time residences in a sensitive area.

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the U.S. Department of Housing and Urban Development (HUD/FHA), The Partnership for Advancing Technology in Housing (PATH), or any PATH-affiliated Federal agency or private company. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.

Details

Because the systems are custom designed, they are applicable for scales ranging from a group of two homes to a whole town. The components of a complete system might include: an individual septic tank for each residence; connections to a trunk line; an anaerobic filter; a recirculation tank that cycles effluent several times through a sand filter; and a drainfield. The sand filter consists of an impermeable liner, a distribution network in a clean sand substrate, gravel, topsoil and plants. Low-flow plumbing fixtures could act as "pretreatment" to minimize required filter area. Since the homeowner is no longer wholly responsible for the volume and quality of his waste, motivation to be conservative is less. However, since the homeowner is now partially responsible for the volume and quality of a collective, motivation to be responsible is higher. In the end it may balance out.

Installation

Systems must be custom designed and built. Less excavation is required than for multiple independent systems. The possibility exists for retrofitting onto some existing septic system components.

Benefits/Costs

Because the bulk of the septic system is confined to one area, residential construction in new subdivisions can be consolidated, providing more contiguous open area and common space. Maintenance, although more frequent, is shared by the community, and therefore should be comparable costwise to individual systems in terms of maintenance and electricity. A shared system retrofitted to 10-homes was installed for approximately $80,000. In comparison, a series of independent sand-filtered systems would cost about $110,000. It is expected that the cost savings in new construction would be bigger. With proper maintenance these systems should last longer than individual systems. Treated water is high quality and could be directly released to a river or aquifer recharge.

Limitations

The system must be monitored more frequently than individual systems, perhaps every 6 months. The participants may need to have a legal agreement to protect each other and to detail responsibilities.

Code/Regulatory

Some state legislatures, such as Oregon, have passed laws to control urban sprawl by promoting alternative septic system designs which can be used on marginal rather than arable land. If local health department does not recognize the practice or will not allow adequate reduction of the combined drainage field, costs will increase.

Availability

These systems have been installed all over the US. They rely on mostly conventional materials and components used in combination.

Contact(s)

Do you have a specific question about this technology and/or its 'real life' applications? Try the contacts listed below:

Tennessee Valley Authority
Water Management Resources Group
Haney Building 2C, 1101 Market Street
Chattanooga, TN, 37402-2801
423-751-7328