I just replaced my hot water heater (Rheem 50 gal. gas, direct vent). After connecting the water lines, turning on the water again, and filling the tank (but before I connected the gas), I slowly opened all the faucets in the house to bleed the air out. All the faucets worked except in the first floor powder room. Neither the hot nor cold water lines work. What's going on?

The aerator on the end of the spout is clogged with debris.

Thanks, I hope it's that simple a solution. The sink has a separate faucet for the hot and cold. How unlikely is it that both faucets would clog up at the same time? It seems very strange. A friend suggested that the shutoffs have an inner pressure valve that might have triggered. Does that sound feasible?

Not at all.

I assume you mean you have a hot handle and a cold handle but they both flow out of the same spout, since truly separate hot and cold valves date back to the1930s, which I don't think you have. Clean the aerator on the end of the spout.