From Seattle Public Utilities:

Seattle Public Utilities crews will conduct routine hydrant flow testing near 3084 SW Avalon Way starting at 11:30 pm on Tuesday, September 24, and lasting until 5:30 am on Wednesday, September 25. During and after testing, some customers in the area may experience temporary discolored water. If this happens, the water should clear on its own- or try running the cold tap for a few minutes. If the problem persists, contact SPU’s 24/7 Operations Response Center at 206-386-1800.

That’s the number to use any time you get unexplained brown water, as we’ve reported many times.