Why does David enjoy the bathroom so much?

From the text:

He would always remember the bathroom with its gleaming pale-green bath and all that clear, clean water that came when you just turned a tap. You could have as much hot water as you liked and sit in it right up to your neck. And there was soap, large pieces of it, that smelled much better than the two cakes he had bought himself. It rubbed into a beautiful soft lather that made you quite, quite clean. And when you had finished, there were large, soft, clean towels to dry yourself on. And there were little sticks to clean your nails with, and you could brush your teeth. David had never tried that before, and the first time he made his mouth sore doing it. But it was wonderful to be so clean.