Snana or bath belongs to the Paschath Karma therapies, the treatments after the Panchakarma or the Pradhanakarma. However, Snana or bath is not an Ayurvedic treatment.
In Ayurveda, the ancient medical system of India, it is viewed in as a daily activity, after an oil massage called Abhyanga. Oil should be applied all over the body and sensitive parts like face, ears and soles of feet should be massaged gently.
Warm water is preferred for bath. It would be better is the water is boiled with herbs, depending on the physique of the person. However, the water should be cooled well before having bath. One shouldn't administer warm water on head.
Cleansing agents like green gram powder and herbal shampoos assure a complete herbal and healthy bath. Having a bath at noon is not ideal. The best time is the morning or the afternoon, just before the sunset. Bathing immediately after taking food should also be avoided.