TAPPI TIP 0416-05: Demineralized water is widely used as makeup to boiler feedwater in the pulp and paper industry. The high purity of demineralized water makes it well suited for steam generation, especially in boilers with operating pressures that exceed 6.4 Mpa [900 psig]. However, because the water is so pure, small amounts of contamination may significantly affect its characteristics and threaten the operating reliability of the steam system. Consequently, operators should be trained to take action in response to feedwater contamination before significant damage occurs. To aid in this training, the Water treatment Subcommittee of the TAPPI Steam and Power Committee published recommended actions for common water chemistry conditions that require immediate response. The water chemistry conditions covered were high and low boiler water pH, silica intrusion, black liquor contamination and feedwater hardness excursions. This paper updates those recommendations and includes new recommendations for feedwater iron contamination. The needs of each pulp and paper mill are different. Consequently, these recommendations should be adapted to each individual mill situation. In all cases, when a deviation from normal water quality occurs, operators should notify their management. This paper deals with response to contamination of high purity boiler feedwater. Obviously, preventing contamination is the best operating mode. To that end the Water Treatment Subcommittee of the TAPPI Steam and Power committee has published a paper entitled Water Quality and Monitoring Requirements for Paper Mill Boilers Operating on High Purity Water. Plants that experience episodes of contamination should adopt its recommendations.