I want to fix up a run down abandoned house, so how do I fix plumbing?

I need to fix the plumbing now... any ideas on how I can? This house is run down and abandoned but its not for sale so how can I fix the place up? mainly the plumbing. I got the eletricity to work already. I seen some old papers that said something about MP is in the restroom so what is this and how do I fix it? All Answers will help