From June 2018, the Super-Kamiokande (SK) detector is undergoing a necessary refurbishment to move into its next phase: SuperK-Gd. Dissolving gadolinium (Gd) into the otherwise ultra-pure water will add to SK the ability to efficiently tag neutrons. Gd has the largest thermal neutron capture cross-section emitting a gamma cascade with total energy of 8 MeV. This has to be compared to the single 2.2 MeV gamma produced from the neutron capture on hydrogen. Neutron tagging capabilities will become a new powerful tool both for signals and background reduction in many analyses.

The test bench for SuperK-Gd has been EGADS, a R$\&$D project that aimed to demonstrate the feasibility of this idea and that started in 2009. EGADS has shown that Gd sulfate can be easily dissolved and has optimal optical properties to be used in a water Cherenkov detector. At EGADS it has been shown that a very good water quality can be achieved and kept thanks to a novel water purification system specifically designed to keep a good water quality while not removing the dissolved Gd.