Some of the challenges in papermaking have been the same for many years, however the demands from the market are increasing continuously and, together with them, the challenges for the paper mills. We consider it is the time to put a lot of efforts together to help papermaking industry to comply with these new demands on a cost-effective way. When it comes to the wet-end chemistry and stock preparation this is a clear and actual challenge. Many developments have been done in developing green chemicals with higher efficiency, machine suppliers are improving the efficiency of each unit, fiber recovery and water cleaning technologies are also under continuous improvement, but the degree of implementation of those advances is still limited. From our perspective, a mindset change is needed, where all those developments are combined to improve the product properties and the process efficiency. Process waters have a very important role to play in that, and in this presentation, we will demonstrate the link and importance that keeping the process water components under control can give to the process. Those improvements were evaluated at lab scale, demonstrated at pilot scale and then implemented at mill level. We will show how the performance of the process chemicals is affected by the process water components, and the impact on the product quality. We will also describe the methods used to understand and evaluate those impacts and describe in a full-scale test how improving the process waters lead to energy savings and the possibility to improve the product performance. The designed methodology can be of use for: - Chemical suppliers, that need to evaluate and demonstrate the performance on challenging processes, such as closed water loop mills. - Companies looking to save water and energy, identifying the costs related to their actual water management and therefore the benefits to implement the right technologies. - Water cleaning technology suppliers that are nowadays not implemented in paper mills, that would be able to demonstrate the removal of the right contaminants and the potential savings that this technology can give to the specific mill. - Paper mills with challenges due to changes in their incoming water quality, or when there are increasing demands from the market that require adaptation of the process chemistry, unlocking possibilities for further development.