The beneficial functions of forests to protect and stabilize source waters, ‘reducing floods and augmenting low flows’, are termed as ‘Shui Yuan Han Yang’ (SYHY) in Chinese Pin Yin and "Soo Won Ham Yang" in Korean. The term in Chinese characters first appeared in the forest legal documents in Japan in 1897 and formally adopted by the Japanese government and the scientific community around 2001. However, the SYHY term is much debated in Japan. What entails SYHY is poorly defined and has been largely ill-interpreted in practice of forest ecological restoration in China. To many, the perception that the increase in forest converge increases water resources including low flows persists, resulting in concerns among scientists and practitioners. This was not surprising as the forest-water relationships are complex and variable, and how forests affect the hydrological cycles at multiple scales have been under debate globally. This commentary attempts to tract the origin of the concept, the definitions, and causes of controversies, and explores how to best use the concept for guiding forest restoration campaigns in China and beyond. We conclude that SYHY services should consider forests role in both improving soil infiltration capacity and elevating water use by forests when evaluating the effects of vegetation-based ecological restoration. These two processes co-exist in influencing high flows, low flow, and total flow in forested watersheds and affect SYHY for a particular forest. We stress that forest hydrological functions are not SYHY services, and so they must be assessed separately with consideration of human water needs under different socioeconomic conditions. Different strategies in watershed management developed on forest ecohydrological principles are needed to achieve forest SYHY goals.