In an industrial cooling circuit supplied with raw river water, the scaling phenomena can reduce cooling efficiency and even lead to the shutdown of the power plant. During the last twenty years, various methods have been developed in order to estimate the scaling propensity of natural waters, which involve the precipitation of calcium carbonate (CaCO3), the main component of scale. The Fast Controlled Precipitation (FCP) is a non-electrochemical method which consists in CO2 degassing from water by a moderated agitation. FCP allows quantifying the scaling propensity for natural water. It could be a useful tool in order to prevent the scaling risk in industrial installations. In this study, efforts have been made in order to make the FCP method controllable and reliable. For the first time, FCP was applied to raw water (raw river from the Seine River) during a long period of time. It gave some insights on the scaling propensity of the Seine water, depending on the water quality and on the season. The FCP method also appeared to be very sensitive. It could be used to assess the efficiency of a humic acid treatment towards scaling. This work showed that natural compounds such as humic acids contained in river waters could have, at low concentration, a great impact on their scaling propensity.