Is it possible that a UTI can be caused by a different water type i.e. if you drink bottled at home but then have tap water out or hot water (possibly from an Urn which is either not clean or the water is not hot enough). Mums been acting strange, took her to the doctors who though it could be a possible UTI and prescribed antibiotics again. On the way back, dad wondered if the fact mum has been out the last three days drinking hot water / tap water contributed to it?