Voltea has commercialized a technology for softening of water and desalination using membrane capacitive deionization called CapDI©. In essence, via an electro-dialysis (ED) process, the technology can be used to remove dissolved salt from a variety of water sources ranging from tap water and brackish groundwater to industrial water. EMI Twente was involved in the early development of this technology. Our task was to develop novel cost-effective ion selective membranes suitable for the softening of water and desalination applications using the capacitive deionization technology, fully characterize them and to compare their performance with commercially available membranes using various process conditions. This was done both at the lab and pilot scale. The findings from this research project gave a good overview of the crucial importance of some process parameters and material properties on the performance of the technology.