Chronic venous insufficiency (CVI) is a progressive and common disease that affects the superficial and deep venous systems of the lower limbs. CVI is characterised by valvular incompetence, reflux, venous obstruction or a combination of these symptoms, with consequent distal venous hypertension. Clinical manifestations of CVI include oedema, pain, skin changes, ulcerations and dilated skin veins in the lower limbs. It places a large financial burden on health systems. There is a wide variety of treatment options for CVI, ranging from surgery and medication to compression and physiotherapy. Balneotherapy (treatments involving water) may be a relatively cheap and efficient way to deliver physiotherapy to people with CVI. This is an update of a review first published in 2019.