Here's the link (water.phila.gov) - it even tells you you have 3 plants from which to choose. Regardless, you're drinking water sourced from a local river.
Sad news though - your water commissioner is a nigger.
Naw, the letter says the 'lead' isn't from the plant, it MAY be from the connection to the main
Go back to the beginning and re-read what I wrote - specifically why you are looking for information on the pH of the water exiting the plant. That's why knowing which plant serves you is important.
Trying to help you here...