Bithynia leachii is species of small freshwater snail with an operculum, an aquatic prosobranch gastropod mollusk in the family Bithyniidae.

It is a Palearctic species found in North Africa and Europe to East Siberia.

There are 4 to 4.5 very convex whorls forming a short cone with a very deep suture in comparison to Bithynia tentaculata.

The spire is shorter and less sharp than in Bithynia tentaculata.

[9] This species requires clean, calcium-rich water, which is slow-running and thickly weeded.