The water supply of many countries in Southeast Asia has significant water problems and it is being affected, amongst others, by both high salinity and high arsenic concentrations in groundwater. This study presents an overview of a laboratory study using a lab-scale membrane capacitive deionization (MCDI) unit and arsenic-spiked model water. CDI is a novel technology for the electro-chemical desalination of brackish water with low energy consumption. In addition, removal performance of co-ions ( NH 4 + ;   Mn 2 + ) https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9781351046633/8978195a-ffaa-498f-8e06-bee4769ddb72/content/eq242.tif"/> typically found in groundwater in the region, and that have a negative influence on other conventional arsenic removal technologies, were also studied with increasing concentrations of NaCl (0–2.0 g L−1). Results show a high dependency of the removal efficiency of selected ions on the TDS concentration, resulting in lower adsorption rates for substances in µg-range such as arsenic.