The features of a liquid jet-based broadband terahertz (THz) generator that includes an optical part and system for a liquid jet formation are described. This system is based on the trapezium-shaped slit-type nozzle, the output of which is limited by two parallel blades. The applications of this generator for studying the optical-to-THz conversion efficiency for various liquids and THz energy temperature dependence are demonstrated. A trend for a decrease in the optical-to-THz conversion efficiency when using high-temperature water is revealed. This trend is interpreted through the increase in the THz wave absorption of the water jet. This system allows to achieve the optical-to-THz conversion efficiency up to 0.1% in the case of α-pinene double-pulse excitation.