Abstract: A flow responsive counting apparatus comprising in combination a) conduit means having an inlet and an outlet; b) means mechanically responsive to fluid flow for measuring volumetric flow of water; c) means mechanically responsive to fluid flow for totalling "on-off" water flow cycles; said conduit means interconnecting in series the means for measuring volume flow and means for totalling on-off water flow cycles. The apparatus interconnected in an appropriate water line in an automatic car wash can provide a tamper-resistant means for counting the number of vehicles washed in the automatic car wash.