Water Quality Analysis

Constituents in red were NOT detected.  They are presented at the level in which detection is possible with available technology.

Supplementary Information

#Why are some concentrations different in the untreated vs. treated water

 

Portland Water District Analysis of Water Supplies
(as tested on February 25, 2008, unless otherwise noted)

 

Constituent

Units

Greater Portland Untreated

Greater Portland Treated1

Central Fire
South Portland (Distribution)

Steep Falls Untreated

Steep Falls Treated1

MCL (for comparison only)2

Physical

Color

SU

10

5

5

<5

<5

15

Conductivity

µS

47

69

72

235

205

**

Total Residue

mg/L

12

21

33

109

83

500

Turbidity

NTU

0.2

0.2

0.2

0.1

0.1

1

Inorganic Non-metals

Residual chlorine

mg/L

N/A

1.8

0.8

N/A

0.7

4.0

Alkalinity(as CaCO3)9

mg/L

4.8

9.3

8.8

13

21

**

Carbon dioxide

mg/L

2.1

1.0

1.0

17

1.4

**

Ammonia – N

mg/L

<0.02

0.4

0.2

<0.02

<0.02

**

Nitrite – N

mg/L

<0.005

<0.005

<0.005

<0.005

<0.005

1

Nitrate – N

mg/L

ND

0.1

0.1

1.2

0.9

10

Chloride

mg/L

7

9

9

11

8

250

Dissolved Oxygen

mg/L

14.2

16.8

13

9.3

12.7

**

Fluoride

mg/L

0.06

1.04

1.01

0.08

1.01

4
Hardness(asCaCO3)

mg/L

9

9

10

26

25

150

pH

SU

6.4

7.9

7.6

6.7

7.7

8.5

Silica

mg/L

2.7

3.0

3.1

8.8

9.6

**
Phosphorus mg/L 0.0 0.68 0.65 0 0 **

Sulfate3

mg/L

N/A

5

N/A

N/A

6

250

Inorganic Metals

Arsenic4

mg/L

N/A

<0.0005

N/A

N/A

<0.0005

0.05

Barium4

mg/L

N/A

0.0034

N/A

N/A

0.0080

2.0

Cadmium

mg/L

<0.0003

<0.0003

<0.0003

<0.0003

<0.0003

0.005

Calcium

mg/L

2.7

2.8

2.8

7.6

7.0

**

Chromium

mg/L

<0.002

<0.002

<0.002

<0.002

<0.002

0.05

Copper

mg/L

<0.02

<0.02

0.03

<0.02

<0.02

1.3

Iron

mg/L

0.02

0.03

0.04

0.07

0.02

0.3

Lead

mg/L

<0.002

<0.002

<0.002

<0.002

<0.002

0.015

Magnesium

mg/L

0.57

0.57

0.6

1.8

1.8

**

Manganese4

mg/L

N/A

0.0014

N/A

N/A

0.006

0.05

Mercury

mg/L

N/A

<0.00005

N/A

N/A

<0.00005

0.002

Nickel

mg/L

<0.002

<0.002

<0.002

<0.002

<0.002

0.1

Potassium

mg/L

0.44

0.48

0.49

1.93

1.67

**

Selenium4

mg/L

N/A

<0.002

N/A

N/A

<0.001

0.05

Silver

mg/L

<0.0003

<0.0003

<0.0003

<0.0003

<0.0003

0.05

Sodium

mg/L

4.4

8.8

9.1

32

28

100

Zinc

mg/L

<0.02

0.16

0.13

<0.02

<0.02

5

Aggregate Organic

Carbon, total organic5

mg/L

2.6

2.4

N/A

0.6

0.6

**
Pesticide/Herbicide6
  µg/L

N/A

ND

N/A

N/A

ND
Asbestos7
(million fibers/L) 106f/L

N/A

< 0.12

N/A

N/A

N/A

7
Radionuclides
Gross alpha8

pCi/L

N/A

0.117

N/A

N/A

5.48

15

 1. Chlorine and pH vary throughout the distribution system so values at your tap may differ from this locale.  Also, iron, copper and lead can be affected by the condition of distribution pipes and interior plumbing.
 2 MCL= Maximum Contaminant Level. The highest level of a contaminant that is allowed or recommended in drinking water.
3 Sulfate – Greater Portland analyzed in June 2007.  Steep Falls analyzed June 2005
4 Arsenic, barium, manganese, mercury and selenium analyzed in June 2007. Steep Falls analyzed June 2005.
 5 TOC analyzed in December 2000.
 6 Pesticide/herbicide analyzed in June and September 2005 (Gr. Portland) and June 2005 (Steep Falls).
 7 Asbestos analyzed in June 2002 in Cumberland area.
 8 Gross alpha analyzed in May 2006
9 Alkalinity Greater Portland Untreated analyzed April  2008
** - MCL does not exist for these constituents
NA – Not analyzed
ND – None detected

 

Why are some concentrations different in the untreated vs. treated water?

Constituent concentrations in the raw, untreated water are extremely stable throughout the year and from year to year.  However, constituent concentrations in the treated water may be modified as part of the treatment process.  Therefore, the treated water concentrations are accurate as tested on February 25,2008 (or date specified).   A distribution system sample site at the Central Fire Station in South Portland has also been included for your information.  Constituent concentrations in the treated water may change slightly with passage through the distribution system so water from your tap will be similar, but not necessarily identical to that at this South Portland site.

 

 

How is the water treated?

Greater Portland: Up to 52 million gallons per day (normally 23 MGD) can be pumped from Sebago Lake through the ozone contact tanks.  Each contact tank has five chambers where ozonated air can be bubbled up through the water.  It is the contact of ozone with the water that accomplishes disinfection.  The ozone concentration is measured in each chamber.   By the time the water reaches the end of the contact tanks, the primary disinfection is complete and the ozone has converted back to oxygen.  Chlorine and ammonia are then added to provide long lasting, continued disinfection in the water mains.  Other chemicals are also added at this point to help reduce corrosion.  They include sodium hydroxide for pH adjustment, and zinc orthophosphate for corrosion control.  Fluoride is added for dental health.

Steep Falls: This well system supplies the community with approximately 28,000 gallons of water each day.  Water is drawn from the wells by a vacuum system then pumped to a series of three tanks where the water is aerated for radon removal.  Chlorine is added to maintain a disinfectant residual in the system and sodium hydroxide is added for pH adjustment.  Fluoride is added for dental health.

 

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