Construction

• The leach field is the part of a septic system that receives partially treated wastewater from a septic tank. It is constructed of several perforated pipes. These pipes are laid over a bed of gravel and then covered with straw or untreated building paper. The leach field is covered with a layer of soil, and grass is planted over it. A typical leach field looks like a normal area of lawn.
  
  

Function

• The perforated pipes in a leach field are designed to spread wastewater evenly throughout the soil. The wastewater that pumps from the septic tank into the leach field has already been partially treated, and the tank has separated out most of the solid waste. Once the wastewater passes into the leach field, natural processes in the soil continue to remove harmful pollutants, bacteria and viruses. Most of the wastewater returns to the environment by sinking deeper into the soil and flowing back into the groundwater supply. Some of the wastewater moves upward, where it either evaporates or is dissipated by the capillary action of grasses.
  
  

Indoor Maintenance

• According to the Environmental Protection Agency, there are several preventive practices that can prolong the life of a leach field. Homeowners should eliminate or minimize the use of garbage disposals, because food products can clog both septic tanks and leach fields. Fixing leaky faucets and installing high-efficiency toilets and showerheads will reduce the amount of water a leach field has to process. Homeowners should never flush inorganic solids--such as diapers, condoms and feminine hygiene products--down the toilet, because these objects can cause the septic system to clog and cease working.
  
  

Outdoor Maintenance

• Homeowners can take preventive measures outside the home to preserve leach field health. Excess water from outdoor sources such as rain gutters and other runoff should be diverted away from the leach field. Homeowners should never drive vehicles over the leach field or park on it, which can compact the soil and reduce its capacity to absorb water. Plant trees at least 50 to 80 feet from the leach field, because roots can clog or crack the pipes.
  
  

Failure

• Preventive maintenance is the best approach to leach field health, because once a leach field has failed, it often cannot be fixed and must be replaced. Even if a leach field can be saved, underground repairs are expensive. When a leach field fails, the entire septic system fails. This means that plumbing may cease to function correctly. It also means that untreated sewage may seep into the groundwater, possibly contaminating drinking water. Because correctly functioning septic systems are so important to the environment, many states require homeowners to preserve an area of their property as a reserve leach field in case the current one fails.