His appearance before the House panel comes after he angered senators by declining to testify before a Senate Intelligence Committee hearing in September focused on foreign efforts to manipulate social media platforms during US elections.
Pichai went to Washington later in September to mend fences. Pichai said that absent any change in the user's settings data will be retained indefinitely.
Among the questions was why image searches for the word "idiot" lead to photos of U.S. President Donald Trump.
Rep. Jerrold Nadler, ranking Democrat on the committee, called the charges "a completely illegitimate issue, which is the fantasy, dreamed up by some conservatives, that Google and other online platforms have an anti-conservative bias".
McCarthy, a California Republican once viewed as close to tech, has been a prime mover behind the hearing and accusations of political bias. Bob Goodlatte, R-Virginia, told Pichai, "I think it is fair to say that most Americans have no idea the sheer volume of information that is collected", and he said he was hoping "to get answers on the extent of data collection and use by Google".
And momentum is building in Congress for legislation to put stricter limits and privacy protections around the big tech companies' collection of data.
Shortly before Pichai's explanation, which was prompted by a question from Rep. Zoe Lofgren (D-CA), Rep. Lamar Smith (R-Texas) had claimed to have "irrefutable" evidence that Google was suppressing conservative search results. "I've got an iPhone", Poe said, waving his device.
"We are a company that provides platforms for diverse perspectives and opinions - and there is no shortage of them among our own employees", he said, denying allegations that Google Search favours liberal content. (He then moved to the left toward his Democratic colleagues on the panel).
Lawmakers didn't hesitate to press their partisan issues with Pichai, who has served as chief executive of Google and parent Alphabet Inc. for the past three years - and was criticized by senators for failing to appear at one of their hearings earlier in the year.
Trump and some lawmakers have raised the possibility of asking regulators to investigate whether Google -which handles almost two of every three online searches in the USA - has abused its clout as a major gateway to the internet to stifle competition. When the topic of the Dragonfly project was brought up Pichai was somewhat evasive and downplayed the significance of the search engine.
That was followed by users of the website Reddit posting articles that contained pictures of President Trump alongside the word "idiot", in an attempt to manipulate the search engine database, in a practice known as Google bombing.
Ortutay reported from NY.