If you get stains and build-up on your toilets, sinks and showers from hard water, you can use vinegar to easily clean it up.

First off, use pure vinegar. Do not dilute it. And do not mix it or use it as the same time as any other cleaners. Mixing vinegar with other cleaners could lead to a dangerous chemical reaction which creates nasty fumes.

For the toilet, put several cups of vinegar in the bowl. Let it sit for a couple of minutes then scrub with a toilet brush. This should take care of the stains.

For the shower and sink, put undiluted vinegar into a spray bottle. Spray it onto the stains (it works for soap scum too, so spray it on that too) and let it sit for several minutes. Wipe, and the stains should be gone