My partner foot is red & swollen with purple patches, yes he had water retention about 2 yrs.no its not going up the leg like cellulitis. any idea?

Clotting?: It sounds as if your partner needs appropriate compression garments to reduce edema and swelling but this is best for venous stasis and not necessarily for arterial insufficency. I would be concerned about varicose veins as well as a potential blood clot(s). A peripheral pulse exam and possible ultrasound imaging may be necessary to evaluate possible etiologies.

See a vascular MD: It could be a venous stasis dermatitis and may need a vascular evaluation.