11.1 - Where does our water come from?
11.1 DO NOW:
Part 1:
Tell me how your break was AND/OR tell me
how you’re doing today.
Part 2:
What are 3 words that come to mind when you
hear “New York City drinking water”?
11.1 CLASSWORK:
Part A: Fun Facts About NYC Drinking Water
Google some facts about NYC Drinking Water. Write 3 here.
Part B: NYC Drinking Water Treatment
Read about the ways NYC water is treated. Write down what you think the purpose of each
treatment is.
What is it Description Purpose
Reservoir The Catskill watershed contains 19 different
control reservoirs. NYC controls can turn each reservoir
“on” or “off”, controlling which of the reservoirs
water is coming from.
Chlorine Chlorine is a common chemical disinfectant. It
can stop bacteria from growing in the water and
on pipes.
UV Light UV treatment can kill harmful microorganisms
like Giardia that can survive chlorine
disinfection.
Fluoride Fluoride is a chemical that is good for your teeth
and helps prevent cavities.
Sodium Sodium hydroxide is a base and when added to
Hydroxide water, it will make the water have a higher pH.
Food Grade Phosphoric acid will create a film on the pipes
Phosphoric and stop them from leaching metals.
Acid
Which of the water treatments from
the table do you think is most
important? Why?
If you had to stop doing one of the
water treatments from the table,
which would you pick? Why?
Honors: What is one more way to treat
water, something you think should be
added to our water, or something you
think our water should be tested for.
Explain!
Part C: How Do We Get Our Drinking Water in the US?
Everyone in your group should read and annotate sections 1 and 6. Before you start, assign a group
member to sections 2-5 each and just read your assigned section!
How Do We Get Our Drinking Water In The U.S.?
Source: NPR, April 14, 2016, ZHAI YUN TAN
Section 1: ALL
Before you take a gulp of water, try to mentally trace where that water that just
gushed out of your taps has been: How did it go from that weird-tasting raindrop to
the clear, odorless water that is sitting in your glass now?
Safe drinking water is a privilege Americans often take for granted — until a health
crisis like the one in Flint, Mich., happens that makes us think about where it comes
from and how we get it.
Our drinking water comes from surface water (lakes, rivers) and groundwater
(tapping into water that is underground). For most Americans, the water then flows
from intake points to a treatment plant, a storage tank, and then to our houses
through various pipe systems.
The most common steps in water treatment used by nearly every utility
company:
A typical water treatment process.
1. Coagulation and flocculation - Chemicals are added to the water. They bind with the dirt
and dissolved particles, forming larger particles called floc.
2. Sedimentation - The floc is heavy, so it settles to the bottom of the tank.
3. Filtration - The clear water on top passes through filters composed of sand, gravel and
charcoal to remove dissolved particles such as dust, parasites, bacteria, viruses and
chemicals.
4. Disinfection - Chlorine or chloramine is added to kill parasites, bacteria, viruses and
germs. Fluorine is added to prevent tooth decay.
Various other chemicals can be added to adjust for hardness and pH levels or to
prevent corrosion, based on the water source. But depending on where you are in the
United States, there can be different challenges, and corresponding methods of
treating drinking water. For example:
Section 2: _________________
Lead Pipes Are Common In The Northeast And
Midwest
(Top) Older pipes can be treated with a chemical to prevent
corrosion and contamination of the water supply.
(Bottom) When Flint, Mich., changed its water source, it didn't treat
the water to prevent corrosion of the pipes, which contributed to high
lead levels in the water.
Lead pipes or fittings are a culprit in the current water crises in Flint, Baltimore and
other cities. Many old water pipes are made of lead, which may leach into the water
supply if preventive measures aren't taken. According to EPA, even low levels of lead
can cause behavior problems, slow growth and affect IQ levels.
While the most effective solution might be to replace lead pipes entirely, water
utilities usually add some form of phosphate to the water supply. That forms a
protective film between the lead pipe and the water flowing through it.
Flint failed to add orthophosphate to control corrosion when it switched water sources
from the city of Detroit to the Flint River; water from the Flint River has eight times
more chloride than Detroit's, which is highly corrosive to the pipe.
Section 3:_________________
Agricultural States May Suffer From High Levels Of Nitrate
In farming communities across the country, water can be
contaminated by fertilizer and livestock. Nitrate runoff in
rivers and groundwater can be common in places with high
levels of farming activities. Fertilizers, manure storage and
septic systems are sources of this pollution. High levels of
nitrate in drinking water can cause "blue-baby syndrome,"
where infants younger than 6 months suffer from shortness of
breath. If untreated, it might lead to death.
Des Moines often has to deal with treating high levels of nitrate in its rivers. The Des
Moines Water Works utility removes it through an ion exchange process in one of its
treatment plants.
Section 4:_________________
Many Western States Drink Saltier Water
Water with high salinity is prevalent in the western
part of the United States. In some places, the water
can be too salty for drinking or other uses and needs
to undergo desalination. These saline water sources
include seawater and brackish groundwater.
Turning seawater into drinking water is a relatively
new concept. The Carlsbad plant in California that
opened last year is the largest seawater desalination plant, and some see it as a
possible solution to the statewide drought.
Brackish groundwater has high levels of salt but not as much as seawater. Texas
relies heavily on brackish groundwater as a water source.
There are two methods plants may use for desalination. One, used by Carlsbad, is
called reverse osmosis; it forces water through semipermeable membranes under very
high pressure.
The other is a thermal process that heats the water to form water vapor, which is then
condensed and collected as freshwater, leaving the salt behind.
Section 5:_________________
Waterborne Diseases Can Happen Anywhere
According to the Centers for Disease Control and Prevention, there were 32 cases of
drinking-water associated outbreaks from 2011 to 2012, the most recent time period
for which they have been reported.
Most of it was Legionellosis, a disease typically spread by water droplets in the air.
The remaining cases were associated with bacteria and viruses that can be killed by
chlorine. To prevent such outbreaks, CDC emphasized the importance of ensuring a
sufficient level of disinfectant, such as chlorine, is present in the water from the time
it leaves the treatment center to when it arrives in our pipes.
Some utilities use ozone as a disinfectant to kill bacteria and viruses, a method some
say is more effective than the usual route of using chlorine. Ozone is bubbled into the
water in huge tanks, destroying illness-causing microorganisms. It also gets rid of
taste and odor in the water.
Milwaukee, Wis., started using ozonation after an outbreak of Cryptosporidium in
1993 killed 69 people and sickened up to 403,000 residents. It was one of the largest
outbreaks caused by a contaminated public water source, according to the CDC.
Section 6: ALL
Some States Try To Protect Their Water At The Source
Watersheds are the areas where rivers, lakes and ponds drain into, and they're a
source of drinking water. Some cities, such as Seattle and
New York, are famous for the regulations and programs
they put in place to protect their watersheds.
New York City gets its water from multiple watersheds that are well-
protected. The quality of the water is so good that it does not need to
undergo filtration at the treatment plants.
In fact, New York City's watershed protection is so good that it's one of the five large
cities in the country where the drinking water supply does not need to undergo
filtration. The city works with farmers and landowners upstream to reduce pollution
and manage land. The Conservation Easement Program sells or donates land to
conservation organizations, limiting the type of development that can occur on it
permanently.
Although the water doesn't go through filtration, it is still disinfected with chlorine
and ultraviolet light, with the usual sludge of chemicals added to control pH and
prevent corrosion.
The EPA regulates approximately 155,000 public water systems in the country,
requiring utilities to conduct tests according to schedule and submit water quality
data. On the other hand, over 15 million Americans rely on unregulated private wells.
From the lake to the tap, water goes through many steps to become safe for us to
drink. It is a crucial process that requires constant monitoring, and — as both history
and current events show — it's one that can be easily threatened by bacterial
outbreaks, natural disasters and human activity.
Section ALL: What are some
important vocabulary words
found in this reading?
Section 1: What are 2 ways -
that water in the US is
typically treated?
Section 2-5: Fill out the table below for each section.
Section 2: Section 3:
Lead Pipes Agricultural
are States May
Common in Suffer from
the Higher
Northwest Levels of
and Mideast Nitrates
Problem(s): Problem(s):
Solution(s): Solution(s):
Section 4: Section 5:
Many Waterborne
Western Diseases
States Drink Can Happen
Saltier Anywhere
Water
Problem(s): Problem(s):
Solution(s): Solution(s):
Section 6: What is special
about NYC drinking water?
What is one more question,
thought, interesting thing
you learned, or reaction that
you have to this article?
Honors: Where and how do
you think Indigenous people
in the US or early colonists
got their drinking water
from? What do you think
might have been some pros
and cons of these systems
compared to how we get our
water today?
