The current movement towards a circular economy has increasingly focused on utilizing materials which were previously considered waste products and converting them into valuable resources. Humus materials, including humic acid, are potentially valuable resources that can be harvested from surface water treatment and used in agricultural applications to increase yield and remediate soil. Humic acid is commonly observed as color in surface water, and in Norway, it is typically removed through coagulation with inorganic salt aluminum sulphate. Although this coagulation method has proven to be very cost-effective, has good performance, is relatively easy to handle and is highly available, it produces substantial amounts of alum sludge. Alum sludge contains a high concentration of alum and many other toxic compounds, like pathogens, organic contaminants, and other heavy metals. To decrease the impact on both human health and the environment, there is a need to use a natural, more sustainable coagulant in surface water treatment processes. Chitosan is a natural substance that has been used successfully as a coagulant in water treatment and is a natural material made from the shells of crustaceans. Chitosan is biodegradable and poses no danger to human health and can be used to filter surface water to remove humic acid without contaminating it. This preserves the potential value of humic acid for use in agriculture as a soil amendment. In this paper, the resource availability of humic acid in Norway is mapped with data from more than 2000 drinking water treatment plants. This is done to identify rich sources of humic acid while a mass balance approach is used to determine how much humic acid can be potentially recovered via chitosan. The results of this paper should be used to identify circular business opportunities which allow for humic acid to be brought back into the natural system, to understand where humic acid is occurring naturally in water sources in Norway, and to investigate how it can be sustainably and efficiently harvested as part of the surface water treatment process.