Activated carbon block (ACB) filters are widely used in point-of-use (POU) drinking technology to remove tastes, odors, and organic compounds from drinking water, and when modified can even remove inorganic pollutants (e.g., arsenate, lead, copper). To introduce ACB technologies to the POU market, thorough assessment and testing are required to meet the National Sanitary Foundation 53 certification. Testing to gain this certification can be costly and time-consuming and is usually only done on the final product before commercial distribution. We developed and explored how a cylindrical "plug" cored from an ACB can be used in a mini-core apparatus with low water volumes, to mimic full-sized ACB performance. These mini-cores allow the same outside-in radial flow conditions as the full-sized ACB. After addressing potential hydraulic channeling problems, tests with chloroform or arsenate confirmed the ability of the mini-core ACB "plugs" to mimic the performance of full-sized cartridge unit. The benefit of the mini-core ACB "plug" lab-scale approach lays the foundation for testing methodologies that can evaluate a range of pollutants, water chemistries, or material modifications using a small fraction of water compared to full-sized ACB filter. Overall, the development of a mini-core ACB testing apparatus is a key advancement towards sustainable water purification, impacting environmental health, resource conservation, and global access to safe water.