I am having my old galvanized pipes replaced. I am not certain, but I believe I have 1/2 supply to the meter and a little 1/2 inch copper on the other side of the meter. The plumber has installed 3/4 inch PEX from that point and then drops back to 1/2 inch to the fixtures. Is this appropriate to have 3/4 with 1/2 inch supply? Will it cause problems?