There is provided a drain recovery system with which power for driving a feedwater pump can be reduced and the feedwater pump can be driven at low costs. The drain recovery system includes: a buffer tank; an assist tank disposed below the buffer tank; a first drain supply line that connects a load device and the buffer tank; a second drain supply line that connects the buffer tank and the assist tank; a drain supply valve; a communication line that establishes communication between the assist tank and the buffer tank; a communication valve; a steam supply line that supplies steam from a boiler to the assist tank; a steam supply valve; a feedwater line that supplies drain from the assist tank to the boiler; and a feedwater pump.

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).