It is native to western Europe,[1] where it grows at the edges of lakes, ponds, ditches and marshes, on wet clay or clay-sand soil, sometimes in water up to 30 cm (12 in) deep.

[citation needed] Pillwort grows on silt and mud at the margins of lakes, ponds and other watercourses that are submerged for at least part of the year.

[4]: 16  Some of the plants growing in association with this species in the UK include water celery (Apium inundatum), marsh pennywort (Hydrocotyle vulgaris) and lesser spearwort (Ranunculus flammula).

In its habitat in shallow water on pond margins or in poached[clarification needed] wet grassland, it seems to grow well in bare locations where it faces little competition.

[3] This is a rare species, declining as its wetland habitats are reduced by eutrophication and drainage, but is regarded as of least concern by the IUCN Red List.