The suggestion that piped water may be associated with poorer Hb status, though not observed in models for dichotomous anaemia, is consistent with findings from Bangladesh showing better iron status in women in poorer, more rural areas who consume tube well water drawn from aquifers laden with iron relative to women in more urban areas who drink piped water (Merrill et al., 2011; Rahman et al., 2016). Here, GSTM1 is linked to anemia (phenotype).