Extremely loud noise when toilet flushes at house water shut off

[Nickm62388]

The last few days whenever we flush toilets, this extremely loud sound comes from this black thing where the water shutoff is for the entire house….it seems to be getting worse, I attached a video for all to hear and try and diagnose and help

 

[GReynolds929]

Can’t see the movie, but it sounds like your describing a pressure reducing valve. They do fail over time and can make noise when they do.

 

[BlueSkyHigh]

The sound is a high pitched squeal and it coming from a black plastic device with the word "Neptune" on it and it is not the typical cone shaped pressure reducer. Can you get a part number off of the Neptune device?