Septic tank regulations are an important piece of a state’s overall wastewater treatment and disposal program. They help ensure that new septic systems are designed and constructed to meet minimum requirements, which reduce the risk of tank failure. They also provide a mechanism for inspecting and testing existing systems to determine whether they are still functioning as designed.
The regulations include design standards, maximum capacities and monitoring. In addition, they include provisions for evaluating and repairing failed tanks, and they address issues related to the operation of septic systems, including the need for routine pumping, cleaning, and maintenance.
Septic tanks must be water-tight. They must be made of sound, durable materials which are resistant to corrosion, decay, frost damage, cracking due to settlement or backfilling, and to buckling from ground movement. All joints below the liquid level of the septic tank or below the seasonally high water table must be sealed with a permanent, watertight seal. Concrete septic tanks must have their walls and floors reinforced, while pre-fabricated tanks such as polyethylene or fiberglass must meet special specifications for wall thickness, fastening of fittings, maximum deformation under load and other factors.
In order to avoid leaks, septic tanks septic tank regulations should have a baffle at the inlet. It should be a pipe tee, elbow or long sweep elbow and should direct the incoming sewage downward to minimize disturbance of the floating scum layer and the settled sludge layer. The baffle should extend below the inlet elevation of the tank a distance equal to 25 to 33 percent of the liquid depth.
The inlet and outlet should be located on the side of the tank away from the house. The inlet should be a four inch vertical slot at least 18 inches wide or a six-inch elbow, and the outlet should be a three-quarters inch pipe tee or long sweep elbow, with a gas deflection baffle extending a distance below the inlet of the tank equal to one-third of the liquid depth. Vent holes should be provided near the top of each compartment to allow the free exchange of evolved gases between the two compartments.
Septic systems must be designed to accommodate a minimum daily flow of 2-3 times the household sewage, including laundry and garbage grinder wastes. The design should also take into consideration future home expansion. In addition, the system should be sized to allow for the possibility that the septic tank will need to be cleaned.
A septic system must be installed in an area free of groundwater. The drainage field should be located well away from swimming pools and other bodies of water, as well as driveways, parking lots and storage buildings. These structures can interfere with the absorption process and overload the drain field.
The drainage field must be kept free of paving, asphalt and gravel. These surface covers can cause excessive solids to be carried into the absorption field and damage the septic tank and absorption system. Covering the drainage field with a garden, lawn or other landscaped area can also prevent proper operation of the tank and absorption system. In addition, children’s play areas and buildings should be located as far from the drainage field as possible, as these activities can cause excess water to enter the septic system and overload the absorption field.