Water mint is visited by many types of insects, and can be characterized by a generalized pollination syndrome,[5] but can also spread by underground rhizomes.

[4][6][7] Unbranched, hairless plants, with narrower leaves and paler flowers, native to areas of Sweden and Finland near the Baltic Sea, have been called Mentha aquatica var.

[8] As the name suggests, water mint occurs in the shallow margins and channels of streams, rivers, pools, dikes, ditches, canals, wet meadows, marshes and fens.

It generally occurs on mildly acidic to calcareous (it is common on soft limestone) mineral or peaty soils.

[12] It is a component of purple moor grass and rush pastures – a type of Biodiversity ActPlan habitat in the UK.