No, but any loose hydrogen from the tank/delivery system is dangerous. When I put in a new water heater I was getting what I thought was entrained air bubbles from the faucet. I got curious and ran the water in the bathroom sink for a minute, then shut it off and flicked my Bic. The fireball was three feet high. The sacrificial anodes that come in the heater reacted with my water when it was heated, and produced hydrogen. I read burning hydrogen isn't visible, but the explosion certainly is.
