character encoding of text in a html file

I am displaying content from different sources, such as database , web service call and so forth, in my website.
 There is no guarantee that the content  i get are in any particular character encoding, some may be in UTF-8 or UTF-16 or something else.

I am getting the content and displaying it as. can I change it to  a particular encoding before , I display it to my web page. at

I am setting the text content inside a div to whatever is returned from a web service call, in code behind page in asp.net website. I'm using C#.