Final answer:
A still water foot spa, also known as a non-jetted foot spa, is the type that does not circulate water, relying instead on the warmth and potential additives for relaxation and therapeutic benefits.
Step-by-step explanation:
The type of foot spa that does NOT circulate water is commonly referred to as a still water foot spa or non-jetted foot spa. This kind of foot spa essentially involves a basin filled with warm water where one can soak their feet. Unlike jetted foot spas that create movement in the water for a massaging effect, still water foot spas rely on the warmth and possible addition of salts or essential oils for their therapeutic benefits. They do not have a mechanism to circulate the water.