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Septic Tanks in South Carolina

Frequently Asked Questions

Image of a man with a questioning facial expression.Do I need to use monthly or occasional additives (treatments) in my septic system to keep it working?

No. In fact, additives or treatments may do more harm to your system than good and even hasten system failure. Some states have banned their use altogether.

  • Additives do not eliminate the need for regularly pumping and maintaining your septic tank, despite some advertising claims. Some products may simply push solids, grease, and scum in your tank out into the drainfield — where they can cause the most damage by clogging up the air spaces around gravel and soil particles and slowing and eventually stopping the cleansing of wastewater.
  • Biological additives are not needed to restore a septic tank’s bacterial balance, since bacteria already reside in human feces.
  • Contrary to myth, never add yeast, dead animals or raw meat to your tank.
  • Never add chemical additives, such as caustic hydroxides and sulfuric acid — they destroy the tank’s bacteria, change the ability of the drainfield to absorb or treat liquids, and may even contaminate water below ground.

Will DHEC use a percolation or ‘perc’ test to determine if my property will work for a septic tank?

No, we haven’t used these tests since the late 1970’s because they are not very accurate in evaluating sites for septic system. Perc tests tell you how fast water poured into a hole will drain out of the hole. A site may pass a perc test during a dry season but fail a perc test during a rainy stretch, when the water table is closer to the ground surface. In the past, some sites in South Carolina passed perc tests but ended up with septic systems that failed to work properly during rainy seasons.

Learn how DHEC more accurately evaluates soil and sites today to determine property suitability for a septic system.

Will DHEC inspect my septic tank upon request?

No, you’ll need to hire a licensed septic system pro to inspect your system. However, our trained staff can answer many of your questions and perhaps offer some helpful technical advice.

Am I legally required to have my septic system inspected regularly?

While S.C. law does not require property owners to have existing systems inspected, some towns have passed ordinances that require their local residents to have their septic systems inspected regularly (See next question).  If you live in an area that does not have a local inspection ordinance in place, the only time you would be required to have your septic system inspected is when you’re building a new home that will use a septic system. DHEC must evaluate the home building site before issuing you a permit to construct the septic system. Without this permit, you cannot obtain a county building permit.

What kinds of inspection requirements may be found in local ordinances?

Local ordinances vary, and some require more of septic tank owners than others. For instance, some local ordinances require an inspection if you want to change the home’s size or designated usage in a way that could potentially place greater stress on the septic system. An example would be if you are renovating your two-bedroom home to become a four-bedroom home, or connecting your home to a system originally designed for a limited use office building. For more information, see our Local Programs page.

Why should I spend the money to have my system inspected regularly if not required by law?

Regular inspections catch problems early so you can fix them before they harm your family’s health, become much more expensive to repair, damage the environment, and possibly create a legal liability for you.

What is an alternative septic system, and are they legal in South Carolina?

Alternative systems use newer technology. Some use sand, peat or plastic instead of soil to treat wastewater. Others use wetlands, lagoons, aerators, or disinfection devices. Float switches, pumps, and other electrical or mechanical components are often used in alternative systems. Alternative systems require more frequent and careful maintenance, but they can sometimes allow you to install a septic tank on land that lacks soils suitable for traditional septic systems or where the undergroundwater level is too high for a traditional system. DHEC considers the use of alternative systems on a case-by-case basis.

Will a high-efficiency toilet help my septic system work better?

Toilets account for one-fourth to one-third of household water use. Most traditional toilets in older homes use 3.5 to 5 gallons per flush. Modern, high efficiency toilets use 1.6 gallons of water or less per flush. If you have problems with your septic system being flooded with household water, a high efficiency toilet could help. You can also lower the volume of water per flush in older toilet by placing a brick in the toilet tank.

Get our money saving tips for reducing the amount of water you use in and around your home.


For additional information, contact: (803) 898-4329 Fax (803) 898-4200