Installation of First Flush on catchment tank

[ef9]

I plan to install a First Flush on my catchment system.

The catchment system is all in place when the home was purchased. I have to cut a section of the existing piping to fit the "T" into place.

Is there a recommended method of cutting the existing PVC to insert the "T" section into place? I was afraid of getting PVC shavings into the catchment tank. Or is this okay and I just use a swimming pool vacuum to suck up the rubbish?

Thanks in advanced,

Stan