I live in a hard water area too and have never had a problem, but I guess good hygiene standards - a toilet duck and a regular squirt of domestos - prevents the unsightly staining that you experienced. And staining (or limescale) doesn't just happen over night so clearly it HAD been allowed to build up. I'm glad to hear you've started taking a bit more pride in cleanliness because given your time in the NHS you more than most must appreciate the detrimental effect poor hygiene has on ones health.