Use of hot water bath for adhakaya (below hip) is very beneficial. while, hot water bath for hairs and eyes is extremely harmful.
Vagbhatacharya mentions that,One should not bath without wetting hairs (i.e. Should wash hairs while bathing).
One should not bath or enter water after being naked and should not sleep in water.
One should not bath into Any lake / pool prepared by others without taking out 5 pits of mud from it.so that lake is cleaned regularly.