They need some reserves but the requirement is almost zero nowadays.
Discussion
There’s a distinction between commercial bank reserves and central bank reserves I thought.
Central bank bank reserves are inter-bank central bank currency, the stuff of QE. Those don’t go out to commercial circuit, the consumer economy.
And then widespread growth of commercial bank reserves are a post-2008 phenomenon lol 
Banks sold their Treasuries to the FED, so the asset treasury was exchanged against FED reserves. On a large scale.
Long but excellent: https://lynalden.com/money-printing/