parts of beaverton get water from the tualitin river and haag lake (I think), along with hillsboro and aloha, and I think just part of beaverton
but by the time the water gets to you the sediments would mostly settle out, and you might have noticed the difference already if you do have it, because since late june this year the columbia water field has been used to supply as much as 50% of the water supply. Its just bad for me in troudale since I am at the start of the supply pretty much
check this map though, it tells you the water districts around the area
http://www.tvwd.org/images/service_area_map.jpg
and this, unrelated article about contruction, has info on sources,
http://www.beavertonoregon.gov/departments/publicworks/utilities/drinkingwaterprogram.aspx