Ideas for reducing noise on fresh water pumps

The problem usually isn't the pump but is most likely water hammer in the PEX piping leaving the pump. What I have found to eliminate noise in my past few rigs is to move the lines at several locations about 1/2" with hand while pump is running until the noise reduces. I then take nylon zip ties and then use the zip tie to hold and secure the line (in the desired new noise reducing position) to the nearest stud or anything that you can wrap zip tie around. You may find that the PEX lines also hammer in other areas of the trailer, such as beneath sinks or in basement storage, etc.
This is one of the first mods I have made to my last few new rigs (where I had noise issues) and I have been able to eliminate most noises.