Systems and methods of efficaciously washing body cavities, specifically including the nasal cavity, wherein a fluid flow is governed in at least one of degree and direction of issuance. Governing of the degree of fluid flow can involve an applicator that is affixable to a fluid source, wherein the applicator can variably constrain the degree of fluid flow being issued. Governing of the direction of issuance can involve the applicator, when affixed to the fluid source, issuing the fluid flow in a specific direction, relative to the fluid source, and an indicator of the fluid source's general orientation relative to vertical.