Septic systems installed after January 1, 2007 are equipped with a sewage effluent filter. This filter minimizes sludge and suspended solids from passing into the septic leaching bed from the tank, extending the life of the system. The filter, however, does require some maintenance and it’s recommended that it be inspected once per year. This is why septic tank lids on installations after this date cannot be covered – they need to be easily accessible.
On average, septic systems installed before 2007 should be inspected every 3 years. With minimal usage, inspections can sometimes be stretched to 4 or 5 years.