A hinged water valve (26) for use in a watering (38, 46) system (50) of a poultry house includes rigid sight tubes (20) connected with hinged water valves (26). Each hinged valve (26) includes a valve body (28) with a valve cap (30) hinged to the valve body (28) with at least one hinge pin. The valve (26) permits flow of water into the sight tube (20) when the sight tube (10) is in its upright operational condition but prohibits flow of water toward the sight tube (20) when the sight tube (20) is pivoted to a substantially horizontal cleaning condition. An internal plunger (32) interacts with an internal seat (36) of the valve body (28) in a sealing manner. A biasing spring (40) urges the plunger (32) into contact with the internal seat (36) of the valve body (28) but with the valve cap (30) in the upright condition, the stem (50) forces the plunger (32) away from the internal seat (36) opening a flow passage (41).