CORROSIVE WATER, LEAD, AND COPPER IN
PRIVATE WATER SUPPLIES OF PENNSYLVANIA
A Quick Refresher
Water Quality Units of Measure
•Milligram per liter (mg/L) = parts per million (ppm)
•Most common unit for larger concentrations
•Commonly used to report copper concentrations (sometimes lead)
•Microgram per liter (µg/L) = parts per billion (ppb)
•Smaller unit used mostly for trace metals and organics
•Commonly used to report lead concentrations
•Factor of 1,000 difference so move decimal 3 places
•0.050 mg/L = 50 µg/L
•100 µg/L = 0.100 mg/L
•Corrosivity is measured using a unit-less corrosion index
A Quick Refresher on Drinking Water Standards
•“Acceptable” level of the pollutant in drinking water
•Enforced for public water supplies by PA DEP
•Primary Standard or MCL
•Pollutants that cause a health problem in drinking water
•Lead MCL = 0.015 mg/L or 15 µg/L
•Copper MCL = 1.3 mg/L
•Secondary = aesthetic (RMCL or SMCL)
•Copper RMCL = 1.0 mg/L
WHAT IS CORROSIVE WATER?
•Water that is aggressive toward metal plumbing
components causing metals to dissolve into the
water
•Causes no direct health effects by drinking
•Causes indirect health problems due to
dissolution of copper, lead or other metals from the
household plumbing
•Can be caused by water quality (corrosive water)
or electrical current (galvanic corrosion)
•Water quality problems can be naturally occurring
or due to land use (mining, etc.)
Scale Formation
The opposite of corrosion
Moderate scale deposition
Severe scale deposition
Caused by deposition of calcium carbonate (hardness)
Corrosion Tendencies
• Rainwater cisterns – most corrosive
• Springs
• Wells
• Varies by aquifer type
Geology and Groundwater
of Pennsylvania
More on Drinking Water Standards
• Corrosivity
– Recommended MCL = “non-corrosive”
– Neutral or positive corrosion index
• Copper
– Primary MCL (gastrointestinal) = 1.3 mg/L
– Secondary MCL = 1.0 mg/L (metallic taste threshold, green stains, )
– Health effects – rare due to taste avoidance above 5.0 mg/L but most
often gastrointestinal. Long term liver and kidney damage
• Lead
– Primary MCL – 0.015 mg/L (15 µg/L)
– From a pure health perspective, standard should be lower
– Health effects – neurotoxic, irreversible brain damage, gastrointestinal
upset, lethargy, paralysis
Water Testing Techniques
• Corrosivity
– Collect water after flushing the lines for 5-10 minutes
– Corrosivity is calculated based on water tests for pH, total dissolved
solids (TDS), alkalinity, hardness, temperature
• Copper
– Standard method is a “first draw sample”
– Collect water from drinking water faucet first thing in the
morning before running any water
• Lead
– First draw sample
– Dissolved versus total
Dissolved vs. Total Lead
300
Total lead = 6 to 20 µg/L higher than dissolved lead
Total Lead (µg/L)
250
200
150
100
50
0
0
50
100
150
Dissolved Lead (µg/L)
200
250
Measuring Corrosive Water
Langalier Saturation Index (LSI)
•
•
•
•
Corrosivity is MUCH more complex than just pH!
The index is calculated based on various water quality results
Measure of waters ability to dissolve or deposit calcium carbonate
Determine pH of calcium carbonate saturation and compare to actual pH
of water sample to determine corrosivity
– LSI = pH(actual) – pH(saturation)
– pHs = Temperature factor + TDS factor – Hardness factor - Alkalinity
• LSI < 0 = aggressive water (corrosive)
• LSI = 0 = water is balanced
• LSI > 0 = water is scale forming
• -0.5 to -1.0 – mildly corrosive
• -1.0 to -2.0 – moderately corrosive
• Below -2.0 = highly corrosive
LSI Limitations
• LSI is NOT a perfect indicator of corrosivity
• LSI generally works well to predict water corrosivity under typical
conditions for Pennsylvania groundwater supplies
• LSI is most predictive of corrosivity for water containing more than 40
mg/L of alkalinity and pH of 6.5 to 9.5
• Unusual water supplies (i.e. soft+high pH, unusual calcium complexes,
etc.) can be poorly predicted by LSI
Online LSI Calculators
• There are many online calculators that you
can use to calculate the LSI based on water
quality inputs
• http://www.advanced-watersystems.com/technical/calculations_and_tabl
es/langlier.html
• http://www.csgnetwork.com/langeliersicalc.h
tml
How Common are the Problems?
Data Sources
• Penn State University (Dr. Bill Sharpe) - 1983
– 695 samples throughout Pennsylvania
– Included pH, corrosivity index, copper
• Penn State (Swistock, Sharpe and Robillard) - 1990
– 1,600 samples across PA
– Testing included first draw lead
• Penn State (Swistock et al. 2007)
– 701 samples across PA
– Testing included first draw lead, pH and hardness
• Penn State Ag Analytical Laboratory
– 1,506 samples across PA from 2007 through 2014
– Testing included pH, corrosivity, copper (running water and first draw) and lead (running
water and first draw)
Removing Lead from Plumbing
• SDWA – Section 1416 (1986)
– Solders and flux <0.2% lead
– Fixtures < 8% lead
• SDWA – 2011 – Revision of Section 1416
– Effective January 2014
– Redefines lead-free
– Reduces 8% to 0.25% by weight
– Provides exemptions for non-potable plumbing
Overall = 18% below RMCL, 2% above RMCL
Overall = 30% soft, 31% moderately hard, 15% hard, 24% very hard
Frequency of Corrosive Water
70
Percent Failing Standard
60
1983
2007
50
40
30
20
10
0
Lots of corrosive waters have a good pH
Corrosivity and pH
4
Corrosivity Index (LSI)
2
0
-2
-4
-6
-8
4
5
6
7
8
pH
9
10
11
12
Prevalence of Copper
• Sharpe et al., 1985 reported copper above the MCL in 2% of 695 running
water samples across PA
• Penn State AASL lab reports 0.9% of running water samples exceed
copper standard in 2013-14.
• These %’s may be biased high due to non-random samples, unconfirmed
sample collection protocols, etc.
• Penn State AASL lab reports
– 21.9% of first-draw samples exceed 1.0 mg/L of copper
– 19.2% of first-draw samples exceed 1.3 mg/L of copper
– 4% of first-draw samples exceed 5.0 mg/L of copper
• Overall – not unusual to find copper above MCL in first-draw samples
presumably due to corrosion
Corrosivity and Copper
14
1,506 samples
2007 to 2014
Penn State AASL lab
Copper (first draw) – mg/L
12
10
8
6
4
2
0
-6
-4
-2
0
Corrosivity Index (LSI)
2
4
Prevalence of Lead over Time
Percent Failing Standard
100
80
1990
First draw samples
More random sample sets
Reduction perhaps due to 1991 Federal Copper and Lead Rule
2007
60
40
20
0
19
12
Regional Occurrence of Lead
(1990 Penn State Study)
Percent above 15 µg/L
100
80
60
40
20
Low # of
samples
0
State
NC
NE
NW
SC
SE
SW
Correlation Between Corrosion and Lead
•
•
•
•
•
•
•
701 water wells
84 (12%) contained lead above 15 ppb
Statistically significant factors correlated to lead were geology and household
plumbing type (metal vs. plastic)
93% of lead levels above 15 ppb occurred in water supplies with a pH <7.0
80% of lead levels above 15 ppb occurred in water supplies with “soft” water
70% of lead levels above 15 ppb occurred in homes with plumbing installed before
1991
Only 1 out of 84 homes with elevated lead could not be linked to corrosion in any
way (noncorrosive water, new plumbing, plastic components).
Testing is Critical!
Awareness of Lead is Very Low
% Aware of Problem in Their Water
60
701 water well samples, 2006-2007
50
40
31
30
18
20
20
11
8
10
0
0
Coliform
Bacteria
E. coli
Bacteria
pH
Nitrate
Lead
0
Arsenic
Pesticides
IF Copper and Lead originate from
corrosion, can we simply run the
water to avoid these issues?
Effect of Running Water on Copper/Lead
•
•
•
•
•
85 of 89 samples (96%) with high first-draw copper were reduced below 1.0 mg/L
after running the water
76 of 79 samples (96%) with high first-draw lead were reduced below 0.015 mg/L
after running the water
But…
Running water is wasteful unless it is done once in the morning to store water
Running water does not protect the plumbing from eventual leaks due to
corrosion
First Draw vs Running Copper
14
Copper (first draw) – mg/L
12
10
8
6
4
2
0
0
2
4
6
8
10
Copper (running water) – mg/L
12
14
Water Treatment
anion exchange
disinfection
oxidation
cation exchange
pH adjustment
filtration
adsorption
demineralization
Match the pollutant with the correct process!
WATER TREATMENT
Percent of Survey Respondents
40
30
20
10
0
53% have some water treatment
Average cost = $1,127
About 10% unnecessary
WHOLE HOUSE (POE)
TREATMENT
Process
Treats
UV light
bacteria
Chlorine
Bacteria, iron, sulfur
Softener
Hardness, some iron
Carbon filter
Organics, radon, sulfur
Sediment filter
Turbidity
Oxidizing filter
Metals, sulfur
Acid neutralizing filter
Low pH, corrosive water, lead, copper
Soda ash injection
Severe corrosive water
Acid Neutralizing Filter (ANF)
Control
Valve
Neutralizing material
Tank
FAUCET (POU) TREATMENT
•Remove most pollutants but only for small amounts of water
•Not recommended for some pollutants (methane, organics, radon, etc.)
Brita Filter
Reverse Osmosis
WHAT ABOUT PUBLIC WATER SUPPLIES?
• Copper and lead are difficult issues for public water suppliers because
they generally result from corrosion of household plumbing
• Action necessary if more than 10% of tap samples exceed the MCL’s
• Public water suppliers may add corrosion control chemicals to their
treated water to prevent corrosion in homes
General Messages for Private Water System Owners
• Testing is critical because
• Corrosivity and copper are common problems
• Lead lacks any noticeable symptom and is very toxic
• Testing for corrosivity, copper and lead most important for:
•
•
•
•
•
•
Combination of acidic and soft water (especially in crystalline and sand/gravel aquifers)
Homes with copper plumbing systems
Especially copper plumbing installed before 1991
Homes noticing blue green stains in sinks, tubs
Homes with a noticeable metallic taste to water which has sat in pipes
Persistent gastrointestinal symptoms
• Running the water can be used to avoid most issues but treatment is
necessary to avoid stress on plumbing
• Rare issues with copper and/or lead in groundwater require reverse
osmosis or other treatment
For More Information…
Penn State Cooperative Extension Resources
http://extension.psu.edu/water
Questions?