Installation of a normal bathtub

Dear Raghuam

       Bath tube should be in one piece.The vertical height of the flanged or rolled edges shall not be more than 30mm. The hot andcold water, overflow and waste with separate traps and shall be of non ferrous metal or stainless steel. The diameter of the waste and overflow pipe should not be less than 25 mm and inside slope be 1in 30 towords the out let. Before finishing bath tub may be water tested to ensure it drain correctly and there are no leaks.Grab bar and soap dish should be planned at convenient height in relation to bath tub and tub controls are placed at comfortable height. See link below

http://www.gharexpert.com/articles/Drainage-,-Sanitary-System-Plumbing-1813/Purchasing-Guidelines-Sanitary-material-Pr_0.aspx

These days most of the bath tubs are made of fiber or PVC material which requires proper filling to be done beneath with lean sand mortar mixure to support the base of the tub. An improper bottom support can reduce the life of your tub. This is my personnel experience.