I'm not a doctor or nurse, but please let me put my 2 cents in -

Pelrad, what do you mean by "lukewarm"? Have you ever measured the temperature of the bath water? Over here, "lukewarm" means "somewhat warm" and any water that people would call "warm" would probably be warmer than body temperature and therefore useless for bringing down a fever. It seems to me the bath should be "cool" to relieve anything.