Water Quality Information | Written By Actual Experts

Anatomy of DC's Tap Water

Hydroviv Water Quality Assessments @ Monday, July 25, 2016 at 1:38 pm -0400
It may seem strange for a water purification company to write a level-headed blog post about municipal tap water, but you have to give credit where credit is due!  Municipalities are tasked with taking water from the sources like the Potomac River and making it comply with federal drinking water standards, and doing this on an enormous scale.

The Washington Aqueduct (Army Corps of Engineers)and DC Water (District of Columbia Sewer and Water Authority or DC WASA) are the two government entities that produce and distribute Washington D.C.’s tap water.  The Washington Aqueduct collects water from the Potomac River, treats it, and sells it to DC Water, and DC Water is responsible for distributing the water to homes and businesses in DC, as well as maintaining water quality standards along the way.  
"Potomacwatershedmap" by Kmusser - Own work, Elevation data from SRTM, hydrologic data from the National Hydrography Dataset, urban areas from Vector Map, all other features from the National Atlas.. Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Potomacwatershedmap.png#/media/File:Potomacwatershedmap.png
The source of all Washington D.C. tap water is the Potomac River. The Washington Aqueduct transforms untreated water from the Potomac River into the water that flows from our taps.  The multi stage treatment process starts by screening out large objects (e.g. sticks & twigs), and allowing large particles (soil, silt, sand) to settle out naturally.    After this step,  aluminum sulfate is  mixed into the water, which causes small suspended particles and colloids to aggregate and settle out.  The water is then passed through a large gravity-fed filtration bed comprised of charcoal, sand, and gravel.  After this step, chlorine is added to the water, which kills microorganisms, and ammonia is added, which converts the chlorine to chloramine.  Finally, fluoride (as hexafluorosilicic acid)  and orthophosphate (a corrosion inhibitor) are added, and this water is purchased by DC WASA to distribute to their customers in The District.   

DC WASA does much more than “keeping the pipes flowing” (which with more than 1300 miles of pipe is a logistical feat on its own), they also employ a team of dedicated water quality experts, all working to ensure that water quality meets or exceeds standards set by US EPA.  This means running 24/7 compliance (tests that they are legally obligated to do)  and voluntary (above and beyond) monitoring programs throughout the city.  One interesting aspect of this voluntary program is maintaining mobile laboratories that are staffed with technicians that can be dispatched to investigate emergencies and respond to customer complaints.  

DC WASA also puts a great deal of time and effort into community engagement and public awareness. DC WASA participates in over 100 community outreach events each year to help customers understand the valuable water services they provide.  One example of these programs is the Clean Rivers Project, where DC WASA promotes best practices practices to minimize the amount of sewer overflow that is discharged into D.C.'s waterways.  In addition to managing a water education program for District students, DC WASA hosts annual town hall meetings in every ward of the city.

Throughout my career, I’ve had the opportunity to work with a number of municipalities (both large and small), and DC WASA does a very good job with information transparency.  I would encourage all residents to check out their website (www.dcwater.com) for more information, which includes things like: water quality reportsoverall strategic planand the role that residents play in maintaining water quality within their own home.

Lead Contamination in Flint, Michigan Drinking Water

Analies Dyjak @ Monday, July 25, 2016 at 1:26 pm -0400

Eric Roy, Ph.D.  |  Scientific Founder

***11/20/2019:  Note from Eric.  It’s been recently brought to my attention that the July 16, 2015 date on this article may have been incorrect, and that the correct publication date is October 14, 2015.  We’ve changed the date listed on the article to reflect this.***

I wanted to take a make our readers aware of a largely unreported disaster that is underway in Flint, Michigan. The residents of Flint, MI are being poisoned by lead in their tap water because the municipality messed up... big time. In this post, I'll focus on the science behind lead contamination, the facts (as we know them) of what happened in Flint, and touch upon another incident in recent history where a similar thing happened.

​All water has impurities in it. Most impurities are harmless (e.g. dissolved oxygen, minerals), some are harmful (e.g. lead, arsenic, mercury).  

Impurities typically enter tap water in 3 ways:

1.  Some are found in the source water (e.g. naturally occurring minerals)
2.  Some are  deliberately added  as part of the treatment process (e.g. chlorine)
3.  Some are picked up along the way from the treatment facility to the tap. 


Lead is almost never found in source water at dangerous levels, and nobody deliberately adds lead to their water supply, because it's toxic.  Lead can, however, be be introduced to tap water as it flows from the treatment facility to the tap.

How is Flint’s drinking water picking up lead in transit?

It’s pretty straightforward:  Nearly all homes with plumbing installed before the 1986 use lead-containing solder to join copper pipes. Lead can also be found in residential plumbing fixtures  manufactured before 1998.   Additionally, some older homes use lead service line pipes to connect water mains to homes.   Proper water quality testing (e.g. pH, chloride, toxic metals) and corrosion control practices (e.g. monitoring chloride levels, maintaining a slightly alkaline pH, adding corrosion inhibitors) are what keep residents with older plumbing and service connections safe from lead contamination.  This is not unique to Flint.  Unfortunately, it's not always done correctly,  and residents suffer.

In Flint, as well as other places where high lead levels have leached into municipal tap water  (e.g.  Washington, DC in the early 2000’s), monitoring and corrosion control measures failed, which allowed lead to dissolve from pipes/fittings/fixtures and poison the residents.

What changed in Flint to cause the lead contamination problem?

In 2014, Flint stopped buying its tap water from Detroit (which has proper corrosion control measures in place), and began collecting their water from the Flint River as part of a plan to switch to a different water supply.  During the changeover process, the municipality failed to implement effective corrosion control measures, and the corrosive water allowed lead to leach from lead-containing plumbing.  
Because proper water quality monitoring procedures were not in place, the Lead problem was not widely discovered until recently.

​What Now?

Flint has announced that it will resume buying water from Detroit, which gets its raw water from Lake Huron and has proper monitoring and corrosion control measures in place.   This is a great first step, but it's important that Flint keeps monitoring their water for lead, because the pipes can continue to leach lead while the corrosion control measures build up the protective layer on the inside of the pipes.  The length of time this takes will depend on the degree of corrosion, and whether or not Flint's water will have "boosters" of the anti corrosion chemicals.

Until lead levels drop, residents are being urged to use a quality water filtration system that effectively removes lead.  Contrary to some of the information out on the internet... boiling water before use does NOT decrease the amount of lead.
  It is critical that Flint residents use a filter that effectively removes lead, and also changes the cartridges on a regular basis.  I would expect that the filtration capacity (in gallons) for lead would be much lower than the manufacturer claims, because the gallon capacity ratings were determined using water with much lower lead concentrations than what is currently being measured in Flint.  

Even though there is a plan moving forward, this type of incident almost certainly caused harm to some residents Flint, and the areas most affected by it were probably homes with older plumbing.  Even though lead contamination is odorless and tasteless, it has devastating effects on human health.  Since Flint began using the Flint River as a water source, numerous children have tested positive for high levels of lead in blood, and a number of schools have recently shut down water fountains due to high lead levels.   When a similar lead contamination issue occurred in Washington DC between 2001-2004, stillbirths shot up during the affected years (Edwards, 2013).   As was the case in Washington, DC, the full extent of harm likely will not be realized for several years.

*** Update June 2016:  We are getting a lot of questions from Flint residents about what to do now.  The message that we want to communicate to people in Flint is that you now have a world leader in Mark Edwards actively working with the city to help fix the problem.  There is quite literally no person on earth with more credibility than Dr. Edwards on this topic, and nobody with a better track for helping people who have been affected by this sort of disaster.  Please listen to him with open ears.  He will not lie to you.  There are a lot of far less credible people who are looking to elevate their status by saying things that will resonate with residents.  Please do not listen to them.  This problem will take longer to fix than it took to create, but understand that you now have the top expert on earth working on the problem.

Sources:​

M. Edwards. Fetal death and reduced birth rates associated with exposure to lead-contaminated drinking water. Environmental Science & Technology. Published online December 9, 2013. doi: 10.1021/es4034952.

Other Articles We Think You Might Enjoy:
Tap Water Chlorination:  The Good, The Bad, The Unknown
Fluoride in Municipal Tap Water:  What You Need To Know
​Disinfection Byproducts:  What You Need To Know

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