The invention relates to a method for draining water from a tank (22), more particularly a clarification tank, wherein water is optionally drained via a draining apparatus while maintaining a substantially constant liquid level (23).

The invention relates to a method for draining water from a tank (22), more particularly a clarification tank, wherein water is optionally drained via a draining apparatus while maintaining a substantially constant liquid level (23).

A double-bell siphon for liquid flow control that improves upon existing bell siphons by the addition of an outer bell which helps the bell siphon to stop siphoning when the liquid level drops below the intended level. Optionally, a cup further enhances the ability for the siphon to stop properly.