While the Water Footprint (WF) is used as a management tool by the private sector, few published studies simultaneously consider all three of its constituent components in its estimation. The components are the Blue Water Footprint (WFblue), the Green Water Footprint (WFgreen), and the Grey Water Footprint (WFgrey). In the case of cellulose production, the only paper published to date did not consider the WFgrey because of the difficulty in finding data relative to natural water quality or to the effluents’ composition. In this context, this article seeks to analyze the WFgrey contribution to the WF of cellulose as well as its consequences for actions to mitigate the negative impact of production processes on water bodies. The study took place in a hypothetical industry located at the Paraíba do Sul River watershed, Brazil. The analyses considered pollutants, such as total chloride, total phosphorous, and phenol—all present in pulp production effluent and regulated by legislation in the three main producer countries in the world. The results showed that the industrial WFgrey can account for up to 55% of the total WF for cellulose production. Additionally, the results indicated considerable variations in environmental standards as well as in the chosen pollutants. Finally, the reduction of the WFgrey values should not be considered an end in itself, without considering the environmental and political context in which the production process takes place.