A good idea but is it a flush or drain? Flush you need incoming cold water pressure to clean out the settled sediment. Somewhat off topic but if you're doing plumbing, I put a new 40 gal water heater in to replace a leaking 50 gal and I put a thermostatic blending valve on the outputs to keep the water from leaving the heater at any temp greater than 120f. For safety and lets me store more hot water and blend it down to a safe 120f so my 40 gal acts like a 60 gal.Thanks for all the comments
Definitely going to install a filter. Tying into copper lines, so no plastic valves.
Figured I'd do a water heater flush while I had the water off also.