There is much debate over the number of interviews needed to reach data saturation for themes and metathemes in qualitative research. The primary purpose of this study is to determine the number of interviews needed to reach data saturation for metathemes in multisited and cross-cultural research. The analysis is based on a cross-cultural study on water issues conducted with 132 respondents in four different sites. Analysis of the data yielded 240 site-specific themes and nine cross-cultural metathemes. We found that 16 or fewer interviews were enough to identify common themes from sites with relatively homogeneous groups. Yet our research reveals that larger sample sizes—ranging from 20 to 40 interviews—were needed to reach data saturation for metathemes that cut across all sites. Our findings may be helpful in estimating sample sizes for each site in multisited or cross-cultural studies in which metathematic comparisons are part of the research design.