Before extrusion, the HDPE can be pigmented to yield color-coded pipe. Common PEX tubing colors are natural (hazy clear, unpigmented), white, black, red and blue. The red and blue colors are used to help plumbers and homeowners distinguish between hot and cold water supply lines.
No, there has never been a US President from an independent party; however, at the time of his presidency, George Washington was not affiliated with a political party at all, as there were no parties in the brand new United States of America.
The last President of the US who was neither Democrat or Republican was Millard Fillmore (1850-1853), who was a member of the Whig party. One could argue that the last (and only) President who wasn't a member of any political party was George Washington.s was also pointed out, the last non Republican or Democrat to become president was Millard Fillmore. You could also argue that John Tyler and Andrew Johnson (as mentioned by Andrew Stein) were not really affiliated with a party while they were in office.