Pipes under concrete.
If you have to install pipes under concrete made sure that your trench is uniform and the correct depth and proper slope. Make sure there are no high spots or low spots in the trench. High spots can squeeze the pipe out of round and cause a restricted flow and low spots can cause the pipe to sag or break.
If you are burying copper pipes under concrete you should check with your local plumbing inspector. Some areas still require that copper line be protected from the concrete by wrapping the copper or installing the copper in a another pipe to prevent corrosion from being in contact with the concrete. This is not required in all areas.