Vented Lids For An Aerobic Treatment Unit

Pretreatment systems, or Aerobic systems, are now being required to have vented lids installed on all new systems. The Aerobic Treatment Unit, or ATU, is the pretreatment device in which the effluent must go through before going out to the drain field. Vented lids were not always required, so most ATUs do not have them. The reason for the change has to do with the algae that can, and does, build up in a system. When a lid is vented, it can reduce this build up, and will also reduce the frequency of pump outs. Charcoal vented lids can help with the septic smell. Home owners are not currently required to change the ATU lids to the vented ones, however, it is recommended. Below are photos of two different types of vented lids. The top photo is the older version, which is no longer recommended as groundwater can get in, as the holes are on the sides. The bottom photo is the current vented lid, which can be purchased at HD Fowler in Gorst or Ferguson's in Silverdale. Contact information for both can be found here.