What is an onsite wastewater treatment/disposal system? An onsite wastewater treatment/disposal system is the means by which an individual home or a cluster of homes cleans and disposes of its wastewater. Usually this is known as a septic system. A conventional system is composed of a septic tank for pretreatment and a drainfield used for disposal of the wastewater. Each system, however, must be designed according to specific site conditions to ensure proper treatment.

Do I need an onsite wastewater treatment system? You will need to consider an onsite wastewater treatment/disposal system if you live outside the reach of a centralized wastewater system. However, as the City of Austin continues to expand further into the hill country, the costs for centralized wastewater collection and treatment systems tends to increase. Thus, the need to consider either individual or cluster-type onsite treatment and disposal systems becomes evident.

How do I choose an appropriate onsite wastewater system? Environmental appropriateness is the most critical factor when determining the suitability of a particular onsite disposal system for a specific land type. Another factor is cost effectiveness of the system, both initial capital costs and long-term operation and maintenance costs should be taken into consideration. Here is a step by step plan for choosing your system. Also, for more information on different wastewater collection, treatment and disposal technologies, contact the US EPA or check out the fact sheets prepared by Community Environmental Services Inc.

Septic tanks are smelly, aren't they? Properly constructed and functioning septic tanks are water tight, and are buried to some depth below the ground surface. In some cases, on exceptionally difficult sites, they may be at least partially exposed at the surface. However, they should not smell, because the wastewater in the tanks is not exposed to the atmosphere.

What if they leak? Leaking septic tanks should be replaced, to prevent adverse impacts to public or environmental health. A good reason to have periodic re-inspections of all onsite systems is to identify leaking septic tanks. The effluent from septic tanks flows either to a subsurface drainfield for final treatment and disposal in the soil system, or is treated further to a level needed for the particular site conditions, prior to either subsurface or surface disposal.

Who will manage the system? For very basic/conventional onsite systems, typically the property owner is responsible for seeing that any necessary repairs are made, or problems are corrected, as/if revealed through inspections or observed by the property owner. For some more sophisticated types of onsite systems, a maintenance contract may be required under the permit to operate the system. Also, a local designated management entity might assume responsibility for the on-going care of onsite systems within its jurisdiction. A monthly user fee might be charged for this service.

Does it cost more than a centralized wastewater collection and treatment system? There is no simple answer to this question, either one way or the other. However, onsite or decentralized wastewater systems tend to be used where development densities are lower, that is, where there is more land space which is available for land-based ("non-discharge") wastewater treatment systems. As development density levels decrease, onsite (decentralized) wastewater systems tend to become more cost-effective than a centralized system. This cost effectiveness over a centralized system is due to the fact that with fewer customers connected to a centralized system, per length of pipe, there would need to be higher user charges and capital recovery fees to pay for the system.

How often do we have to clean out septic tanks? Decades of data on septic systems shows that septic tanks should be pumped once every two to five years. this prevents solids, oils and grease from building up to a level in the tank where they will begin being washing out to the drainfield, and clogging the field lines. Periodic pumping of the septic tank can prevent high repair and/or replacement costs for the drainfield.

Will household chemical use present a health hazard? As is true also for a centralized wastewater treatment system, residents should be careful about what they put into their wastewater system. Soil treatment and disposal systems are relatively tolerant to many pollutants, but care should be taken to read labels on chemical products so that they are disposed of properly. Pouring large amounts of bleach or other disinfectants into a septic system can at least temporarily decrease the system's performance. Normal use of bleach and other household cleaners will not impair the functioning of a septic tank.

What if my neighbor's system has problems? Would it affect me? Depending on the location of your neighbor's system relative to your home or business, problems with their system may or may not directly affect you. However, any observable problems with onsite systems should be reported because they will eventually cause at least some degree of adverse impact to environmental and/or public health. Again, regular re-inspections of all systems would help to minimize such occurrences.

How does the septic work with my water system? Septic systems, or any type of wastewater line, is separated from potable water lines, for public health reasons. The amount of water used in a business or household can however affect the performance of an onsite system. As with homes and businesses using centralized wastewater service, water conservation should be practiced to the extent practicable, and leaky fixtures or toilets should be repaired or replaced as soon as possible.

Why is the City of Austin interested in decentralized wastewater management? Relatively rapid growth has occurred in the Austin, Texas area during the past two decades. Largely due to its many natural, cultural, and educational amenities, Austin has become one of the fastest growing cities in the U.S. Areas in the western, southwestern , and northern portions of the metropolitan area have been undergoing particularly intense growth, with the accompanying pressures to develop infrastructure in response to that growth. Without careful planning and adequate controls, increased urbanization can have adverse impacts on environmental quality resulting in the permanent loss of important or unique natural resources that would diminish the overall aesthetic appeal of the area.

Questions and concerns have been raised locally and at the State level about appropriate planning approaches and development densities that would prevent adverse impacts to the Edwards Aquifer and other sensitive areas in and around the City of Austin. These questions directly relate to wastewater planning and management issues and considerations in those geographic areas. For example, many of the western and southwestern portions of Austin are characterized by fairly hilly, rocky terrain. The construction costs for centralized wastewater collection and treatment systems in those conditions tend to be higher than for flatter and less rocky terrain. A large number of homes to the west and southwest of Austin are currently being served by individual onsite wastewater treatment systems. Also, density of development tends to be much lower overall in those portions of the City as compared with other parts of the Austin area due to a variety of factors, including certain environmental controls and conserved natural or greenbelt areas. As limitations are placed on, or occur naturally for the density of development, the user costs for providing centralized collection and treatment tend to increase. Thus the need to consider either individual of cluster-type onsite treatment and disposal systems becomes evident.

The City of Austin's Water Utility has undertaken this project in order to evaluate a variety of alternative wastewater collection, treatment and disposal technologies for their applicability to conditions in and around Austin. As wastewater service is provided to areas within the City's extraterritorial jurisdiction (ETJ), the city may then better determine the most appropriate type of wastewater service for those conditions. The study area for the project includes all of Travis County and the City's five-mile ETJ.

How does the city plan to manage private onsite wastewater treatment and disposal systems? The successful long-term use of both conventional and alternative wastewater collection, treatment and disposal systems depends largely on the development of an appropriate management approach. "Management" in this case means carrying out a set of policies and practices related to the permitting and care of wastewater systems to ensure public health and environmental protection in a way that is acceptable locally and in accordance with regulatory requirements. The proper maintenance and care of onsite wastewater systems is essential to their successful long-term operation, and for preventing adverse health or environmental impacts or the development of nuisances. Click here to see management program elements currently being considered for onsite wastewater systems.


Information provided by Community Environmental Services Inc.