Purolite NRW37, a mixed bed ion exchange resin which consists of 40% by volume Purolite NRW-100 (strong acid cation exchange resin) and 60% by volume Purolite NRW-400 (strong based anion exchange resin) has been used to treat K Basin water for 5-12 years. Specifically, the change in chemical functionality of the resin was investivated. In addition, the thermal stability of the rinsed product resins and their propensity to undergo rapid exothermic events when heated were evaluated. The organic carbon concentrations of the digestion solution were also determined.