Taking it upon yourself to move water pipes around certainly saves money, but isn’t recommended for novices. Bathroom water pipe relocation takes lots of planning and requisite knowledge, so unless you’re confident in your abilities, it may be best to call a plumber. That being said, the process is similar regardless of who’s doing it, and the degree of difficulty depends on your level of knowledge, experience, and what equipment you possess. Make sure to plan accordingly.
Assuming that you’re moving water pipes in a pre-existing bathroom, the first step is to figure out which sorts of pipes connect your bathroom to the main line. Copper pipes are the most common piping, however, it really depends on when the house was built. If the piping is copper, then you will need to solder the fittings together. If you are not experienced in using a torch and soldering, then this should not be the material you use. There are transition fittings that would be much safer for you to use, and change from copper to cpvc or Pex. To cut copper piping you will need a tube cutter, for cpvc or Pex you will need a plastic pipe cutter.
PEX tubes (which will be obvious by their red and blue coloring) are more flexible than copper. However, keep in mind that the more fittings and angles you install in your pipeline, the more chance of restricting the water pressure to the fixtures.
Positioning the new drainpipe should be relatively simple. All you have to remember is that the drainpipe has to have a quarter inch per foot fall, so the waste and the water move at the same pace. Sink drains should always run from small to larger drains. The Plumbing code requires that all fixtures be vented. The vent pipes should be located behind the wall, but in many older homes, not all of the fixtures were vented. A vent is needed to protect the trap seal, and to help the system drain. Occasionally, the local municipal or the International Plumbing Code might permit the use of an AAV (air admittance valve).
As far as bathroom projects go, pipe relocation can be lengthy and complex. Remember that your home’s plumbing is a synchronized system of parts that all have to be in the right place in order to work together. If you’re doing the work yourself, it’s still recommended that you consult a plumber throughout the duration of the process.