I had the same question a while back replacing my shower valve with a R10000. I removed it during the soldering phase, just did not want to take any chance. Then when I was done I never put it back as I flushed the lines with no valve in place. Someone commented that in a normal whole house plumbing job it is to catch all crud in the lines when flushed and before the valve is in place. Then there is the plug that you have to use if you do not install the valve right away to prevent crossover, that gets in the way of the screen, so again I did not use the screen again because of this.