Adjustable resistance, gravitationally activated, anti-syphon valve

A method of forming an anti-siphon drainage device, having a housing forming an internal chamber;

• an inlet port and an outlet port communicating with the internal chamber and fluidly connected by a primary flow path;
• a valve seat associated with the primary flow path;
• a sloped section extending from the valve seat inside the internal chamber;
• a valve element disposed in the sloped section and capable of seating in the valve seat to restrict a fluid flow into the primary flow path from the inlet port;
• a secondary flow path;
• and a regulator, wherein when the valve element is disposed in the valve seat and restricting the fluid flow into the primary flow path, the fluid flows into the secondary flow path, comprising the steps of:
• forming the primary flow path with the valve seat;
• disposing the valve element in the sloped section;
• forming the secondary flow path;
• and
• disposing the regulator over the secondary flow path to selectively occlude the secondary flow path.