Drinking water which has passed through lead pipes is not good for you, especially for pregnant women and young children, so you might want to replace them with copper or plastic ones. Lead pipes are often found in older style properties. One sure sign is a dark matte grey pipe which turns shiny when scraped with a screwdriver. It is now illegal to use lead pipes or lead solder for plumbing which supplies water.
Click here for more information about why you should check if you have lead water pipes and what to do if you have.