In fact, it is worst mistake you are doing health wise by making bathroom and toilet area in one room. Reason why bathroom and toilet room should not be made in one single room is the health harms which they produce when made in one. What these health harms are which bathroom and toilet room not made separately but made in one room produce?

These are-

1) Favors spread of infection-

Yes, it favors infection spread and hence spread of infectious diseases resulting from these infections. You will ask how it favors it? Do not worry, I am explaining reason for it too here. Well in toilet area every day micturition and urination is done by people using it. It becomes house for disease causing micro-organisms to live. To prevent flourishing of micro-organisms in excreta and urine in toilet area, it is flushed out immediately from toilet seat and regular decontamination of it is done with disinfectants to kill disease causing micro-organisms.

• But, still some air borne disease causing micro-organisms remains in air, that is why it is advised to keep glass window open of toilet room; so that these air borne micro-organisms go outside through window, if they are not killed by fumes of disinfectant phenol or bactericide used in toilet area.
• When the toilet room and bathroom is separate, then contamination spreading disease micro-organisms remain in toilet room, because of barrier of wall between both. But, when bathroom and toilet area made in one room, then their is no wall barrier which can stop disease causing air borne micro-organisms spread from toilet area air to bath area air. Hence favors spread of disease causing micro-organisms.

2) What is harm of attaching conjoined bathroom and toilet area attached to bedroom?

The harm is same as with making bathroom and toilet area in one room mentioned above. Yes, the spread of disease causing micro-organisms from attached bathroom and toilet area easily to bedroom. That is, why it is advised mostly by doctors to keep toilet and bathroom area away from bedroom, even when they are made separately to prevent this disease micro-organism spread.

3) Humidity in bathroom favorable environment for disease causing micro-organisms-

Yes, humidity in bathroom is favorable environment for disease causing micro-organisms coming from toilet area. When they get favorable environment, they do not die easily; their life span and multiplication increase. Whereas, if toilet area and bathroom are made separate, then they do not get favorable environment of humidity in toilet area and die soon and multiply less due to unfavorable dry atmosphere of toilet area.

4) Air borne bacteria of toilet area contaminate your bathroom soap and other basic things-

Yes, it does contaminate basic things you have kept in bathroom; when it is conjoined to toilet area. Bathroom's main purpose is cleaning of body, not the contamination of body from disease causing air borne micro-organisms coming from toilet area; contaminating everything in bathroom even soap, water of bath area, which ever thing you use for cleaning purposes.

5) Similar things it does in wash basin area, when it is made conjoined to toilet area-

Because it then too receives air borne bacteria from toilet area and contains favorable humid environment for disease causing micro-organisms to live and multiply in wash basin.

In short, when bath area and toilet area are made in one single room, it turns bathroom area meant for maintaining hygiene of body by bathing to unhygienic area.