Find zoning codes for septic drain fields from a local zoning authority, agricultural extension office or state environmental department. Local building inspectors are another potential resource for up to date information about zoning codes.
A septic drain field is used to purify water after it drains from a septic tank. Because these fields purify wastewater that can cause human disease, the local health department may require testing before issuing a zoning permit. These tests assure that runoff from the drain field does not contaminate the local water system.
Septic drain fields create a risk for contamination because septic systems cannot be disinfected as other sewer systems can. Septic tanks rely on beneficial bacteria to break down waste; chemical disinfection would destroy the tank's ability to break down solids. This is why a drain field is a necessary second step in the septic system.
When waste water drains into the septic drain field, it filters through layers of soil, gravel, clay and sand. Bacteria, viruses and other disease-causing organisms stay behind in these layers as the water filters through, leaving the water clean. This clean water continues draining until it reaches the groundwater system.
Septic drain fields are not effective at removing petroleum products, chemical solvents, or metals from water. Bleach, detergent and drain cleaner can lessen the effectiveness of septic tanks and drain fields by destroying beneficial bacteria and damaging the field's ability to filter fats.