The water pressure in my house has steadily decreased over the past couple of months, to the point that now there's almost no pressure at all in the shower. Two months ago I replaced the water line from the house to the street after the water company told me I had an 800-gallon-a-day leak. The pressure didn't increase after the line replacement; in fact, it's even less now. The toilet in the bathroom where the shower is takes a really long time to fill, and sometimes I can hear a faint sound like water running hours after anyone's used the water. What could be the problem, and how do I fix it?