for example by being threaded thereto central system css includes a vacuum system that provides a vacuum in pipe p when the level of wastewater in holding tank ht achieves a predetermined level then valve v opens and the vacuum in pipe p pulls the wastewater from holding tank ht to central system css air flows into holding tank ht by way of vent pipe 12 until valve v closes when the level of wastewater in holding tank ht is lowered airflow monitor 10 detects the flow of air through vent pipe 12 and provides a signal when the airflow is occurring as discussed herein now additionally referring to fig2 there is shown a closer view of vent pipe 12 with airflow monitor 10 installed therein airflow monitor 10 can be easily installed in existing vent pipes 12 by drilling a hole through the side of pipe 12 inserting monitor 10 from the inside of pipe 12 through the hole and threading a nut on the threaded portion of monitor 10 now additionally referring to fig3 5 there are shown more details of airflow monitor 10 which includes a base unit 14 a securing means 16 and a light diffuser or refractor 18 in base unit 14 there is an led light 20 a battery pack 22 a reed switch 24 a magnet 26 and a flapper 28 when an airflow moves past flapper 28 which may be a diaphragm 28 it cause magnet 26 connected thereto to move which in turn causes reed switch 24 to electrically close and conduct electricity from battery pack 22 to led light 20 reed switch 24 along with magnet 26 and flapper 28 can be considered a sensor.