Wach [vax] is a village in the administrative district of Gmina Kadzidło, within Ostrołęka County, Masovian Voivodeship, in east-central Poland. It lies approximately 9 kilometres (6 mi) north-west of Kadzidło, 28 km (17 mi) north-west of Ostrołęka, and 121 km (75 mi) north of Warsaw.