Mixed beds can supply particularly high-quality water for a substantial about of time without regeneration meaning less hands-on work by operations in contrast to normal deionization trains which could face regeneration twice a day. However, due to the unfamiliarity of operators and regenerating mixed bed, problems can arise with troubleshooting and when a mixed-bed unit does not function properly it can take some time to get it operating correctly. This article outlines methods for troubleshooting and repairing various mixed-bed systems in North America including faults such as resin problems, mechanical failure and changes in feedwater quality.