W ater: D rin kin g W ater C o n ta m in a n ts C o ntact U s

Yo u are here: Water D rinking Water D rinking Water C o ntaminants Seco ndary D rinking Water Regulatio ns: Guidance

for N uisance C hemicals

Seco n d ary D rin kin g W ater R e g u latio n s: G u id a n ce for

N u isa n ce C h em icals

816-F- 10- 079

W h at are Seco n d ary Sta n d ar d s?

The U .S. Enviro nmental Protectio n A gency (EPA ) has establis hed N atio nal Primary D rinking Water Regulatio ns that set

mandatory w ater quality standards for drinking w ater co ntaminants. These are enforceable standards called "maximum

co ntaminant levels" or "MC Ls", w hic h are establis hed to protect the public against co ns umptio n of drinking w ater

co ntaminants that present a risk to human health. A n MC L is the maximum allow able amo unt of a co ntaminant in

drinking w ater w hic h is delivered to the co ns umer .

In additio n, EPA has establis hed N atio nal Seco ndary D rinking Water Regulatio ns that set no n-mandatory w ater quality

standards for 15 co ntaminants. EPA does not enforce these "seco ndary maximum co ntaminant levels" or "SMC Ls." They

are establis hed o nly as guidelines to assist public w ater systems in managing their drinking w ater for aesthetic

co nsideratio ns, s uc h as taste, color and o dor. These co ntaminants are not co nsidered to present a risk to human health

at the SMC L.

W h y Set Seco n d ary Sta n d ar d s?

Since these co ntaminants are not health threatening at the SMC L, and public w ater systems o nly need test for them o n a

voluntary basis, then w hy it is necessary to set seco ndary standards?

EPA believes that if these co ntaminants are present in yo ur w ater at levels above these standards, the co ntaminants may

cause the w ater to appear clo udy or colored, or to taste or smell bad. This may cause a great number of peo ple to sto p

using w ater from their public w ater system even tho ugh the w ater is actually safe to drink.

Seco ndary standards are set to give public w ater systems some guidance o n removing these c hemicals to levels that are

below w hat most peo ple w ill find to be noticeable.

W h at p ro b le m s are ca u se d b y th ese co n ta m in a n ts?

There are a w ide variety of pro blems related to seco ndary co ntaminants. These pro blems can be gro uped into three

categories: A esthetic effects -- undesirable tastes or o dors; C osmetic effects -- effects w hic h do not damage the bo dy

but are still undesirable; and Tec hnical effects -- damage to w ater equipment or reduced effectiveness of treatment for

other co ntaminants. The seco ndary MC Ls related to eac h of these effects are given in Table 1.

A e st h e t ic Ef fe c ts

Odor and Taste are useful indicators of w ater quality even tho ugh o dor-free w ater is not necessarily safe to drink. Odor

is also an indicator of the effectiveness of different kinds of treatment. H ow ever, present metho ds of meas uring taste

and o dor are still fairly s ubjective and the task of identifying an unacceptable level for eac h c hemical in different w aters

requires more study. A lso, some co ntaminant o dors are noticeable even w hen present in extremely small amo unts. It is

us ually very ex pensive and often impossible to identify, muc h less remove, the o dor- pro ducing s ubstance.

Standards related to odor and taste: C hloride, C o pper, Foaming A gents, Iro n, Manganese pH , Sulfate, Thres hold

Odor N umber (TON ), Total D issolved Solids, Zinc.

C olor may be indicative of dissolved organic material, inadequate treatment, high disinfectant demand and the potential

for the pro ductio n of excess amo unts of disinfectant by- pro ducts. Inorganic co ntaminants s uc h as metals are also

commo n causes of color. In general, the point of co ns umer complaint is variable over a range from 5 to 30 color units,

tho ugh most peo ple find color o bjectio nable over 15 color units. Rapid c hanges in color levels may provoke more

citizen complaints than a relatively high, co nstant color level.

Standards related to color: A luminum, C olor, C o pper, Foaming A gents, Iro n, Manganese, Total D issolved Solids.

Foaming is us ually caused by detergents and similar s ubstances w hen w ater has been agitated or aerated as in many

faucets. A n off-taste described as oily, fis hy, or perfume-like is commo nly associated w ith foaming. H ow ever, these

tastes and o dors may be due to the break dow n of w aste pro ducts rather than the detergents themselves.

Standards related to foaming: Foaming A gents.

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C o sm e t ic Ef fe c ts

Skin discoloration is a cosmetic effect related to silver ingestio n. This effect, called argyria, does not impair bo dy

functio n, and has never been fo und to be caused by drinking w ater in the U nited States. A standard has been set,

how ever, because silver is used as an antibacterial agent in many home w ater treatment devices, and so presents a

potential pro blem w hic h deserves attentio n.

Standard related to this effect: Silver.

Tooth discoloration and/or pitting is caused by excess fluoride ex pos ures during the formative perio d prior to eruptio n

of the teeth in c hildren. The seco ndary standard of 2.0 mg/L is intended as a guideline for an upper bo undary level in

areas w hic h have high levels of naturally occ urring fluoride.The level of the SMC L w as set based upo n a balancing of the

beneficial effects of protectio n from tooth decay and the undesirable effects of excessive ex pos ures leading to

discoloratio n. Informatio n abo ut CD C ’s recommendatio ns regarding o ptimal fluoridatio n levels and the beneficial

effects for protectio n from tooth decay can be fo und at: http://w w w .c dc.gov/fluoridatio n/.

Standard related to this effect: Fluoride.

T e c h n ical Ef fe c ts

C orrosivity, and staining related to corrosio n, not o nly affect the aesthetic quality of w ater, but may also have

significant eco nomic implicatio ns. Other effects of corrosive w ater, s uc h as the corrosio n of iro n and co pper, may stain

ho usehold fixtures, and impart o bjectio nable metallic taste and red or blue- green color to the w ater s upply as w ell.

C orrosio n of distributio n system pipes can reduce w ater flow .

Standards related to corrosion and staining: C hloride, C o pper, C orrosivity, Iro n, Manganese, pH , Total D issolved

Solids, Zinc.

Scaling and sedimentation are other processes w hic h have eco nomic impacts. Scale is a mineral deposit w hic h builds up

o n the insides of hot w ater pipes, boilers, and heat exc hangers, restricting or even blocking w ater flow . Sediments are

loose deposits in the distributio n system or home plumbing.

Standards related to scale and sediments: Iro n, pH , Total D issolved Solids, A luminum.

T a b le I. Seco n d ary M axim um C o n ta m in a n t Levels

C o n tam i n a n t Seco n d ary M C L N ot icea b le Ef fec ts a b ove t h e Seco n d ary M C L

A luminum 0.05 to 0.2 mg/L* colored w ater

C hloride 250 mg/L salty taste

C olor 15 color units visible tint

C o pper 1.0 mg/L metallic taste; blue- green staining

C orrosivity N o n-corrosive metallic taste; corro ded pipes/ fixtures staining

Fluoride 2.0 mg/L tooth discoloratio n

Foaming agents 0.5 mg/L frothy, clo udy; bitter taste; o dor

Iro n 0.3 mg/L rusty color; sediment; metallic taste; reddis h or orange

staining

Manganese 0.05 mg/L black to brow n color; black staining; bitter metallic taste

Odor 3 TON (thres hold o dor number)"rotten-egg", musty or c hemical smell

pH 6.5 - 8.5 low pH : bitter metallic taste; corrosio n

high pH : slippery feel; so da taste; deposits

Silver 0.1 mg/L skin discoloratio n; graying of the w hite part of the eye

Sulfate 250 mg/L salty taste

Total D issolved Solids

(TD S)

500 mg/L hardness; deposits; colored w ater; staining; salty taste

Zinc 5 mg/L metallic taste

* mg/L is milligrams of substance per liter of water

H o w ca n th ese Pro b le m s b e C orrecte d ?

A ltho ugh state health agencies and public w ater systems often decide to mo nitor and treat their s upplies for seco ndary

co ntaminants, federal regulatio ns do not require them to do this. Where seco ndary co ntaminants are a pro blem, the

types of removal tec hnolo gies disc ussed below are corrective actio ns w hic h the w ater s upplier can take. They are

us ually effective depending upo n the overall nature of the w ater s upply.

C orrosion control is perhaps the single most cost-effective metho d a system can use to treat for iro n, co pper and zinc

due to the significant benefits in (1) reductio n of co ntaminants at the co ns umer's tap, (2) cost savings due to extending

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the useful life of w ater mains and service lines, (3) energy savings from trans porting w ater more easily thro ugh

smoother, uncorro ded pipes, and (4) reduced w ater losses thro ugh leaking or broken mains or other plumbing. This

treatment is used to co ntrol the acidity, alkalinity or other w ater qualities w hic h affect pipes and equipment used to

trans port w ater. By co ntrolling these factors, the public w ater system can reduce the leac hing of metals s uc h as co pper,

iro n, and zinc from pipes or fixtures, as w ell as the color and taste associated w ith these co ntaminants. It s ho uld be

noted that corrosio n co ntrol is not used to remove metals from co ntaminated so urce w aters.

C o nventio nal treatments w ill remove a variety of seco ndary co ntaminants. C oagulation/ flocc ulation and filtration

removes metals like iro n, manganese and zinc. A eration removes o dors, iro n and manganese. Granular activated carbon

w ill remove most of the co ntaminants w hic h cause o dors, color, and foaming.

N o n-co nventio nal treatments like distillation, reverse osmosis and electrodialysis are effective for removal of c hloride,

nitrates, total dissolved solids and other inorganic s ubstances. H ow ever, these are fairly ex pensive tec hnolo gies and

may be impractical for smaller systems.

N o n-treatment o ptio ns include blending w ater from the principal so urce w ith unco ntaminated w ater from an alternative

so urce.

W h at C a n Y o u D o?

If yo u are co ncerned abo ut the presence of seco ndary co ntaminants in yo ur drinking w ater s upply, here are a few

s uggestio ns:

FI R S T , i d e n t i fy yo u r local p u b lic w ater s ys tem . If yo u pay a w ater bill, the name, address, and telepho ne

number of yo ur s upplier s ho uld be o n the bill. If yo u do not pay a w ater bill, then co ntact yo ur landlord, building

manager, or the local health department -- they s ho uld k now .

SE C O N D , co n tac t yo u r local p u b lic w ater s ys tem . Inquire abo ut yo ur s upplier's mo nitoring for seco ndary

co ntaminants. A sk for the list of seco ndary co ntaminants w hic h are being mo nitored in yo ur w ater s upply. D oes

the w ater being delivered to the public meet these SMC Ls? If yo u have not yet received notice from yo ur s upplier,

ask how yo u can get a co py of the mo nitoring res ults.

T H I R D , i f yo u receive a p u b lic n ot ice f ro m yo u r local p u b lic w ater s ys tem regarding other drinking

w ater standards -- READ IT C A REFU LLY -- and follow any instructio ns closely. If yo u have questio ns or

co ncerns, co ntact the perso n from the w ater system w ho is indicated in the notice. If that perso n is unavailable,

co ntact either the state drinking w ater pro gram or yo ur local health department.

F O U R T H , co n tac t yo u r s tate d ri n ki n g w ater p ro g ram if yo ur w ater s upplier is unable to provide the

informatio n yo u need. A sk if yo ur w ater s upplier is co nsistently in compliance w ith both primary and seco ndary

drinking w ater regulatio ns. Request a co py of mo nitoring res ults that w ere s ubmitted to the State by yo ur

s upplier. Yo ur state drinking w ater pro gram is us ually located in the state capital (or another major city), and is

often part of the department of health or enviro nmental regulatio n. C o ns ult the blue "government pages" of yo ur

local pho ne book for the pro per address and pho ne number, or call the Safe D rinking Water H otline.

FIF T H , s u p p ort rate i n c reases for yo u r local w ater s u p p lier, w here necessary, to upgrade yo ur s upplier's

treatment facilities to meet drinking w ater standards.

FI N A LL Y , i f yo u h ave a p rivate w ell and yo u think that the w ell may be near a so urce of co ntaminatio n or

may have been co ntaminated -- H A V E YOU R WA TER TESTED by a certified laboratory. A list of certified labs is

available from yo ur state's laboratory certificatio n officer. A list of the certificatio n officers can be o btained

from the Safe D rinking Water H otline.

For M ore In form atio n

For more informatio n o n seco ndary co ntaminants, w rite or call the EPA . A sk for a list of the primary and seco ndary

co ntaminants, abo ut mo nitoring requirements for these, and for a list of the health advisories available for these

co ntaminants.

or call the Safe D rinking Water H otline

at 1- 800- 426- 4791

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