An efficient method is reverse osmosis, it is difficult to efficiently remove these two metals using an adsorbent material. You could try silicas modified with organic arm groups that show affinity for your metals such as crown ethers for example.

Capacitive deionizationis a modern technique, see:

Energy Environ. Sci., 2015, 8, 2296--2319

Water desalination via capacitive deionization:

what is it and what can we expect from it?

M. E. Suss, S. Porada,X. Sun, P. M. Biesheuvel, de J. Yoonf and V. Presser

Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The

technology is based on ion electrosorption at the surface of a pair of electrically charged electrodes, commonly composed of highly porous carbon materials. The CDI community has grown exponentially

over the past decade, driving tremendous advances via new cell architectures and system designs, the implementation of ion exchange membranes, and alternative concepts such as flowable carbon electrodes and hybrid systems employing a Faradaic (battery) electrode. Also, vast improvements have been made towards unraveling the complex processes inherent to interfacial electrochemistry, including the modelling of kinetic and equilibrium aspects of the desalination process. In our perspective, we critically review and evaluate the current state-of-the-art of CDI technology and provide definitions and performance metric nomenclature in an effort to unify the fast-growing CDI community. We also provide an outlook on the emerging trends in CDI and propose future research and development directions.

Actually i want to design it for emergency purposes...these CDI needs a full planned setup!!!