Water Protection Program

On-Site Wastewater Protection

On-Site Wastewater Septic Systems

North Carolina laws and rules require local health departments to evaluate a prospective site for a new septic tank system upon submission of a valid application from the property owner or his/her legal representative. Though sometimes called a "perk test," perk tests are no longer used by any Health Department to determine if a property is suitable for a septic tank system permit. Instead, a site evaluation is completed to evaluate factors like the landscape and topography position, soil characteristics (sand, silt, or clay composition), soil wetness (based on soil color), soil depth, restrictive horizons (hard-pans), and available space for the proposed septic tank system and repair area, if required. Septic sites and drainfields are sized according to the number of bedrooms in a house; when building or re-locating a home or mobile home on a site with an existing septic system, make sure it can accommodate the size of the home.

Some sites have limitations that would affect the functioning of a septic tank system. For some sites, a permit can be issued with specified site modifications, but this option is not always available. North Carolina laws and rules require health departments to advise applicants of any options that may exist for a site, and also set appeal rights.

Effluent Filters

North Carolina laws and regulations for sewage treatment and disposal systems require that effluent filters be installed for all new septic systems. Effluent filters trap solids and some suspended solids, so they do not flow out of the septic tanks. This extends the life of the drainfield and prevents clogging of the drainlines, which can result in sewage breaking out to the ground surface and costly repairs to the septic system.

Preventing Costly Repairs

To prevent costly repairs, septic tank systems should be routinely maintained. A licensed septic tank pumper should pump your septic tank periodically to remove solids (see your local phone directory for pumpers). How often a septic tank needs to be pumped varies depending on the volume of the tank and the number of occupants in the house, though generally most systems should be pumped every 3 to 5 years. This maintenance is critical.

Effluent filters have to be periodically cleaned and returned to the filter retainer, which is installed at the septic tank outlet. The frequency of this also varies. If wastewater from your house plumbing fixtures begins to drain slowly, you or a contractor should check to see if the effluent filters needs to be cleaned.

Limiting the use of kitchen garbage grinders will also reduce solids from entering the septic tank.

Septic System Do's & Don'ts

All wastewater from the home must be plumbed to the septic tank. This includes all sink, bath, shower, toilet, washing machine and dish water.

  • Do keep roof drains and other rain or surface water drainage systems away from the septic tank and system drainfield.
  • Do establish a good grass cover for the drainfield to help prevent erosion and help remove excess water.
  • Do not use caustic drain openers for a clogged drain. These can kill the useful bacteria necessary for proper functioning of the septic system.
  • Never use your septic tank as a trash can. Do not dispose of grease, disposable diapers, kitty litter, paint, tampons, condoms, oven cleaners, cigarettes, etc. into the septic system. Putting these materials in your system may contribute to septic system problems necessitating possible expensive repairs for you.
  • Do not drive, pave or build any structures over the septic tank system area including the reserved repair area if required.
  • Do not plant trees or shrubbery in the drainfield area because roots will damage the septic tank system.

Commercial septic tank system additives are generally not needed. With a minimum amount of care your septic tank system should provide years of trouble-free operation. If you abuse or do not maintain your septic tank system, it is highly likely you will have a septic system failure at some point.

For more information about septic systems and state requirements, visit the NC Department of Health and Human Services' Environmental Health Section.

Private Drinking Water Wells