Aside from artificial and natural reservoirs wasps find water in wet ground as well. The wet sand in a watered planter attracted several wasp families among which this potter wasp, probably Ancistrocerus gazella [Gereys 2016]. Repeatedly she revisited the sand, what indicates she collected water for her nest.

Literature
1 Nederlands SoortenregisterGereys 2016 Gereys, B., 2016. Vespidae solitaires de France métropolitaine: Hymenoptera: Eumeninae, Masarinae. Fédération française des sociétés de sciences naturelles.