I basically agree with Mike that if Webpräsenz is also equivalent to 'web presence' or 'presence on the web,' it's not a particularly good translation for 'website.' But we discussed all that exhaustively in a previous thread somewhere, and I have the feeling it's too late, that train has left the station. And as Mike says, it may at least be better than using Webseite for a multi-page site.
The problem, just to review, is that English has the options
web PAGE < webSITE (more than one page) < web PRESENCE (more than one site/URL, plus all mentions on other websites, such as reviews, directories, search engines, advertising, etc.)
If Webpräsenz refers, misleadingly, primarily to the middle level, it might be nice if at the same time we could add some *different* translation for 'web presence' E>D to show that the two are now largely false friends.
In any case, I would like to plead for including 'website' as one word, however it's translated, as that spelling is quickly becoming the preferred one, though 'web site' is also still widely used, and there are even still some conservative holdouts (including some print dictionaries, slow to catch up) favoring 'Web site' with a capital W.
If it were up to me, I would standardize all entries as follows:
website (also: web site, Web site) - *