The Portland Water Bureau treats Portland's water with chloramination. This process starts with chlorine to disinfect the water. Next the city adds ammonia to ensure that disinfection remains adequate throughout our distribution system.
The Portland Water Bureau also adds sodium hydroxide to increase the pH of the water to reduce corrosion of plumbing systems. This treatment helps control lead and copper levels at customers' taps should these metals be present in the customers' home plumbing.
Portland's water is currently not filtered. The Bull Run source meets the filtration avoidance criteria of the 1989 Surface Water Treatment Rule and has had a waiver from the requirement to filter since 1991.
pH adjustment for corrosion control
The Oregon Health Authority has set water treatment targets for the Portland Water Bureau. These targets reduce corrosion in plumbing through adjusting the pH of the water. We have measured at least a 50 percent reduction in lead at the tap with pH adjustment.
In January 1997, the Portland Water Bureau began corrosion control treatment, raising the pH of the water to to make it less acidic and less likely to leach metals. The treatment consists of adding 4-5 milligrams per liter (parts per million) of sodium hydroxide as part of the water treatment process. The target pH range is 7.8 to 8.0.
Adjusting pH helps reduce levels of lead and copper in tap water in some homes and businesses, and in wastewater treatment discharges.
For water-related activities or hobbies affected by changes in pH, consumers should always follow professional instructions from the product manufacturer or hobby consultant. This includes swimming pools, hot tubs, aquariums, beer or wine making, pet fish, etc.
Testing Your Drinking Water
If you are concerned about the quality of water in your home, you may want to have your water tested. For a fee, private laboratories will test your tap water. Not all labs are accredited to test for all contaminants. For information about accredited labs, call the Oregon Environmental Laboratory Accreditation Program at 503-229-5505 or find the list on the website.
Call The LeadLine for information about free lead in water testing. The program targets testing the water in households most at risk from lead in water: homes built between 1970 and 1985 with pregnant women or children age six or younger in the home.
Related site: Recent water quality monitoring reports