Septic systems, also referred to as onsite wastewater treatment systems, cluster systems, or private sewage systems, are designed to collect, treat, and discharge wastewater from residential, commercial, or industrial use through a series of natural and technological processes. This factsheet will focus on residential septic systems and the best practices for system use and maintenance. Benefits of routine inspection and maintenance include saving money long-term, securing your property value, keeping your household and community safe, and protecting the environment (figure 1). This factsheet provides introductory and essential information to new owners and users of septic systems.
How Septic Systems Work
While many types of septic systems exist, they all serve the same main purpose: collecting, treating, and discharging wastewater from a residential, commercial, or industrial facility. The septic system works by routing used water from a building’s plumbing, such as sinks, toilets, showers, tubs, and washers, to the septic tank, where it is stored long enough for the floaters and sinkers to separate. The floaters include fats, oils, and greases because they float up to the top, while the solids, also known as the sinkers, settle down to the bottom. Once this has occurred, the liquid waste, or effluent, discharges to a drainfield. The drainfield is an area of land designed to accept the effluent through engineered pipes or chambers, which slowly seep into the soil or other media (figure 2). In a properly functioning system, the effluent passes through the soil or other media where contaminants are filtered from the wastewater before entering the groundwater.
What To Do When Moving In
Upon moving in, prioritize becoming familiar with the septic system. Gather any available records that will help you locate the system, including the septic tank and size of your drainfield, and identify the type of system and materials used for the tank and drainfield. Take note of any records that identify the specific type of system as being one of those listed below, as this will be useful to professionals hired to maintain your system.
Also, document if the tank is concrete, fiberglass, or plastic, if able, and any details on the drainfield (see figure 3 for types of information to note). If you are having difficulty finding the above information or if there is no record of a recent inspection from the previous occupant, contact a licensed septic system service provider to schedule an inspection and assist with gaining information on the system.
Locating The Septic Tank and Drainfield
Locating a septic tank and drainfield can be difficult; a good place to start is the local SCDHEC or county records office for property records. Since these entities do not keep records forever, you may need to employ some other ways to find the system. You can try to track down the location by following the plumbing in your basement or crawl space. Look for a sewer pipe, usually a 4-inch pipe, in the basement or crawl space and trace it to where it leaves the structure and enters the yard. You will often find the septic tank and drainfield at least 5 feet from the structure, possibly farther, and a few inches to a few feet below ground, parallel to the sewer pipe exiting the home. Note: the area of a buried system may be a little higher or lower than its surroundings, and a lid should be present (figure 4). You can also use a soil probe every two feet to determine if you “hit” anything. If these methods do not locate the system, contact the neighbors of the property. It is common for neighboring properties to have the septic systems placed in comparable areas, which may lead to finding your tank. It may be necessary to try one of these options:
- look through documents from when the home was purchased
- contact the previous owner of the property
- contact local septic contractors in the area to see if they have previously serviced the unit
- hire a licensed installer who can locate the tank using a probe rod
If a septic system is designed and maintained properly, it can have a life span of 20-30 years. This can be achieved by adhering to the following septic system best practices:
- Routine inspections, pump outs, and maintenance
- Septic tank and drainfield protection
- Efficient water use
- Proper waste disposal
Septic system best practices include inspection and maintenance (figure 5). No state laws exist that require routine inspection; however, it is recommended that you review local ordinances for regulations concerning septic systems. Owners and users of septic systems are encouraged to perform visual inspections, such as checking the drainfield for signs of failure. Owners and users should not inspect and maintain a septic system themselves; the system contains noxious fumes, small spaces, and hazardous conditions. SCDHEC requires inspections, repairs, and pump-outs to be performed by a licensed contractor. These contractors have the necessary training, equipment, and personal protective equipment.
A professional inspection every one to two years can help provide long-term financial savings, secure your property value, keep your household and community safe, and protect the environment. Annual inspections are recommended by SCDEHEC for alternative systems with mechanical parts. Regular inspection also allows you the opportunity to address any minor issues before they become major.
You should expect an inspection to involve locating the system, if not already identified, often a pump out of the tank, and observations and recommendations for current and future maintenance. The septic tank size and the number of users will determine the pump out frequency; generally, a septic professional will advise a pump out once the tank is one-third to one-half full of solid waste. This is typically every three to five years for an average household septic tank.
You need to document all septic system maintenance performed by contractors. Your records should include the date, the contractor’s name and contact information, and services provided, including any comments regarding the septic system (figure 6).
Septic Tank And Drainfield Protection
Do not drive, dig, build or plant deep rooting plants above the tank and drainfield. These activities can break the tank lid and pipes and compact the soil resulting in the soil microbe’s inability to function correctly, ultimately leading to system failure. Grass is recommended for landscaping on drainfields and is beneficial by helping the system optimize oxygen exchange, promote transpiration, and minimize soil erosion. A list of appropriate grasses and groundcover can be found in HGIC 1726, Landscaping Over Septic Drain Fields. Additionally, a list of appropriate plants can be found from EPA in the resources section below.
Efficient Water Use
Water conservation helps to prevent unnecessary work for your septic system. The more water entering the system, the more work is required by the system. Conserving water, such as installing high-efficiency appliances and low-flow fixtures, can be a significant action alongside these simple acts:
- Completely load dishwashers and washing machines before use
- Use one water-based appliance at a time
- Reduce the number of times each appliance is used daily
- Fix plumbing leaks
- Take faster showers
- Turn the faucet off while brushing your teeth
- Use a basin or plug sink to wash dishes
Proper Waste Disposal
Only put items down the drain or toilet that are intended for septic systems. When not septic safe items enter the septic system, the system’s efficiency will be adversely affected, causing problems that can be time-consuming and costly (figure 7).
Don’t Dump Down the Drain
|Fats, oil, & grease from cooking|
|Liquid/chemical drain openers for clogged drains|
|Non-septic-safe household cleaners|
|Other household chemicals such as paint, thinners, oils, etc.|
|Wipes (flushable or otherwise)|
For more information on septic system maintenance, failures, and unique situations, please refer to HGIC 1896, Be Septic Safe: Best Practices for Septic System Maintenance; HGIC 1897, Be Septic Safe: Septic Failures; and HGIC 1898, Be Septic Safe: Unique Situations.
Originally published 05/22