The safety of drinking water is one of the most important
public health issues in the United States or for that matter anywhere. During
the 20th century efforts to achieve safe drinking water lead to developing
drinking water quality regulations under the U.S. Environmental Protection
Agency Safe Drinking Water Act (EPA SDWA). During that time providing safe
drinking water focused on water filtration and treatment to kill bacteria. It
was felt that simple reliable treatment could address any deterioration in
source water quality. Unfortunately, in
our country where population is increasingly concentrated around crowded urban
centers this may no longer be true.
Variations in water quality have undermined the ability of
even advanced water treatment plants to control water quality and treatment and
provide safe drinking water consistently and effectively. The rain and snow
melt carrying pollutants from the air moves through the watersheds into streams
and rivers and picks up additional contaminants along the way. As the water
travels over the land surface or through the ground on its way to the rivers,
it dissolves naturally occurring minerals and vegetation (organic matter) as
part of the natural process. The water also picks up surface contaminants including
pesticides, herbicides and other
synthetic/volatile organic chemicals from agricultural land, golf courses, or
residential and urban lands. Additionally,
some previously unrecognized contaminants in trace amounts, pass through the
treatment plant. There is a need for source water quality protection as an
additional “barrier” to contamination and additional treatment may be necessary
to deliver water free from chemical contamination.
Regionally, the Washington Suburban Sanitary Commission
(WSSC), the Washington Aqueduct, Fairfax Water and Loudoun Water treat raw
water obtained from the Potomac River, Patuxent River and Reservoirs and
Occoquan Reservoir. Potential sources of
contamination in the region include transportation, petroleum pipelines,
agriculture, onsite septic systems, wastewater treatment plant discharges, developed
areas, and minor permitted discharges, storage tank leaks and spills. Contaminants
of particular concern to the water companies include; phosphorus, agricultural runoff,
natural organic matter and disinfection byproduct (DBP) precursors, pathogenic
microorganisms (Cryptosporidium, Giardia, fecal coliform), taste and
odor-causing compounds, ammonia, sediment/turbidity and algae.
Water drawn from the Occoquan Reservoir, the Potomac River, the Patuxent River
Reservoirs is treated in the regional water treatment plants and is
continuously tested for the contaminants regulated under the Safe Drinking
Water Act before being sent to homes and businesses through the region. The first
step is coagulation and flocculation (to make small particles and
microorganisms in the raw source water adhere to each other); sedimentation (to
remove most of those particles and microorganisms); filtration (to remove
nearly all the remaining particles and microorganisms); disinfection (which
varies across the treatment plants but kills bacteria and microbial pathogens);
corrosion inhibitors/ pH adjustment (to minimize the potential for dissolving
lead solder used in older homes and laterals lines); and fluoridation.
Orthophosphate is also added to help minimize lead corrosion and copper pipe
pinhole leaks in home plumbing by creating a protective film in pipes.
To ensure that tap water is safe to drink, EPA prescribes
regulations, which limit the amount of certain contaminants in water that
public water systems provide. The Safe Drinking Water Act regulates almost 90
substance, but that is a tiny fraction of the chemicals in use in a modern
industrialized society. The quality of the water being produced at all our
regional water treatment plants meets or exceeds all the US EPA standards and
requirements. However, not all potential contaminants are regulated under the
Safe Drinking Water Act.
Traces of pharmaceuticals, hormones and personal care
products associated with everyday life in the United States are finding their
way into groundwater and streams through septic systems and wastewater
treatment plants and these micro pollutants can find their way into drinking
water supplies. Drugs that people take are not all metabolized, and the excess
ends up in our wastewater leaving homes and entering the sewage-treatment
plants. These drugs have been detected in streams miles downstream from
wastewater-treatment plants because most plants do not routinely remove
pharmaceuticals from water. Antibiotics and drugs are also used in the
livestock industry, and for streams receiving runoff from animal-feeding
operations, pharmaceuticals such as acetaminophen, caffeine, cotinine,
diphenhydramine, and carbamazepine, have been found in USGS studies.
Other problems are showing up as well, the Environmental
Working Group (EWG) released the results of a new analysis, they commissioned
of tap water samples from throughout the Northern Virginia region. The results detected
some PFAS contamination in 19 samples of tap water ranged from about 6 parts
per trillion, or ppt, in a state park in Fairfax County, to about 62 ppt in a
public park in Prince William County. These levels though much higher than
samples previously taken in Northern Virginia, are still below the U.S.
Environmental Protection Agency’s (EPA) health advisory level of 70 ppt, that
level is screening level, not a health based maximum contaminant level (MCL)
for drinking water. The EPA has decided to move ahead and regulate PFOS and
PFOA two of the group of chemicals called PFAS that are known as “forever
chemicals” because they build up in our blood and organs, bioaccumulate, and do
not break down in the environment.
Fairfax Water says “There are no treatment processes available for drinking water
utilities that would not significantly increase water rates for customers. Nor
would such treatments produce a demonstrated health benefit.”
Changing the water treatment chain at the Corbalis and Griffith water treatment
plants would be necessary to treat the source water to remove PFAS. According
to Fairfax Water this would "significantly" increase the cost of
water for all the residents of Fairfax and Prince William Counties and unless
there is a demonstrated health benefit they cannot justify the cost to the
customers. So, they will wait for the EPA to develop a health based MCL. In
the meantime we need to better protect the Occoquan Reservoir from chemical
spills and accidental releases that are believed to have caused the PFAS
contamination increase.
The Maryland Department of the Environment (MDE) has recently
announced a settlement with
Verso Corporation, owners of the Luke Paper Mill in Western Maryland, for
seepages into the North Branch Potomac River. Samples of the substance being
released to the river suggested the presence of ‘black liquor,’ possibly mixed
with coal ash. Black liquor, a caustic mix of chemicals and wood waste from the
paper-making process at the now closed plant, has a high pH, and contains
hazardous constituents at concentrations that are harmful to aquatic life and
humans. Coal ash contains a range of harmful constituents, including arsenic,
mercury and boron, all of which were found in the Potomac Riverkeepers
sampling. A petroleum odor was also noted by MDE.
The former Luke Paper Mill is upstream of the
intakes for all the regional water treatment plants and though well diluted by
the Potomac can still enter our drinking water treatment plants. Protecting the
Potomac River from chemical spills and releases is necessary to ensure that our
dinking water remains safe. The time has come to limit the life of storage tanks, require removal are remediation of all closed manufacturing plants, and provide a natural barrier to pollution by limiting development in our essential watersheds. Development impacts water quality. Minimizing impervious surface cover and maintaining the tree canopy is critical to the protection of the region’s streams which flow to the Potomac River and Occoquan Reservoir. There is a direct correlation between stream health and impervious surface cover and tree canopy. According to the Northern Virginia Regional Commission, watersheds with impervious surface cover of 10 to 15% show clear signs of degradation, and when impervious surface cover is greater than 25% no longer can support a diverse stream ecology and are dying.