Private Water Well Analysis

If your drinking water comes from a household well, then you are

on a private water supply. Federal and Oklahoma governments do

not regulate privately-owned wells in Oklahoma; therefore, you ,

as the homeowner, are responsible for assuring your water is

safe and of adequate quality for your needs. For this reason,

routine testing for a few of the most common contaminants is

highly recommended.

This fact sheet explains some of the testing that was performed

on the water sample from your well or tap. The results should

establish a baseline of the current quality of your drinking

water. This guidance will assist you with interpreting the

results from a Routine Chemical test panel that includes

alkalinity, chloride, nitrate/nitrite, conductivity, pH, sulfate, total

dissolved solids (TDS), and total hardness, or other individually-

requested tests.

Note that the Routine Chemical panel does not include all of the

Environmental Protection Agency (EPA) primary and secondary drinking

water standard parameters.

Interpreting Your Results

Test results should be compared against the current EPA maximum

contaminant levels (MCLs) and secondary standards (SMCLs) for

the contaminant.

EPA has established MCLs for certain contaminants

which, when present at excessive levels, may have an

adverse effect on human health. MCL concentrations are

the highest concentration of a contaminant allowed in

drinking water.

Note that not all contaminants have MCLs.

EPA has also established National Secondary Drinking

Water regulations that set non-mandatory and non-

enforceable secondary water quality standards for some

contaminants that can make the appearance, taste or

odor of drinking water less pleasing to a consumer.

SMCLs are established as guidelines to assist public

water supply systems in managing their drinking

water for aesthetic considerations. Secondary standard

contaminants are not considered to present a risk to human

health in concentrations at or below the SMCL.

If your tests show a less-than symbol (<) followed by a value, the concentration

of that contaminant in the sample is lower than the lowest concentration the lab

can detect and report. In such cases, it means no signicant concentration of the

contaminant was detected in the sample.

This publication is issued by the

Oklahoma Department of Environmental

Quality authorized by Scott A. Thompson,

Executive Director. Copies have been

prepared at a cost of $0.159 each. Copies

have been deposited with the publications

clearinghouse of the Oklahoma

Department of Libraries.

(Fact Sheets\SELS\Private Well Analysis.

indd 7/2022)

Routine

Chemical Tests

Contaminant

Maximum

Contaminant

Level

Primary

Standards (MCL)

Nitrate (as N) 10 mg/L

Nitrite (as N) 1 mg/L

Secondary

Standards

(SMCL)

Chloride 250 mg/L

pH 6.5 to 8.5 SU

Sulfate 250 mg/L

Total Dissolved Solids

(TDS)

500 mg/L

Private Water Well Analysis

Total Alkalinity

Total alkalinity is a measure of the

buffering capacity of water or its ability to

resist sudden changes in pH. Comparing

the alkalinity and the pH can provide an

indication if your water exhibits tendencies

of either corrosion or deposition.

See Calcium Carbonate Equilibrium for

further information.

pH can range from 0 to 14 standard units

(SU) and is a measure of how acidic or basic

water is. A pH of 0 would be extremely

acidic and a pH of 14 would be very

alkaline. A pH of 7 is considered neutral.

The optimum range for pH in drinking water

is between 6.5 to 8.5 SU.

Chloride

The recommended upper limit for chloride

is 250 mg/L. Chloride is the greater part

of table salt and may impart a salty taste

to water.

Nitrate

The maximum allowable level for nitrate in

a domestic well, a public water supply, or

other primary source of drinking water is

10 mg/L. Nitrates are of particular concern

to pregnant women and infants under six

months old since drinking water high in

nitrates may cause blue baby syndrome,

methemoglobinemia. Nitrates are typically

of little concern for adults or older children.

Sources of nitrates include soil, sewage,

and fertilizers.

Conductivity

Conductivity is typically reported in units of

µmhos/cm, and is a measure of the ability

of water to conduct an electrical current.

Some level of conductivity is normal in

well water. Conductivity increases with

increasing amounts of certain ions such as

chloride, nitrate, sulfate, phosphate, sodium,

magnesium, calcium and iron. Elevated

conductivity beyond usual baseline levels

can be an indicator of water pollution. There

is no EPA MCL for conductivity.

Total Dissolved Solids

The recommended upper limit for total

dissolved solids is 500 mg/L. Water over

that level should not be used if better quality

water is available. Palatability of the water

may be affected. Chloride, sulfate and

alkalinity are primarily responsible for the

dissolved solids content of water.

Sulfate

The recommended maximum for sulfate

is 250 mg/L. Excessive concentrations

of sulfate may act as a laxative to

unaccustomed consumers. A bitter or

gyp taste is often associated with high

sulfate concentrations.

Hardness

Hardness is generally derived from contact

of water with natural accumulations of salts

in soil and geological formations, primarily

limestone, dolomite and gypsum. It is

reported as mg of calcium carbonate per liter

(mg/L). Water hardness can be expressed in

four ways:

• Soft – less than 75 mg/L

• Moderately Hard – between 75 and

150mg/L

• Hard – between 150 and 300 mg/L

• Very Hard – greater than 300 mg/L

Hard waters can still be as satisfactory for

drinking as soft waters depending upon

the tastes of the user. Excessive hardness

may, however, cause laundering difculties

or produce scale build-up in hot water

tanks, xtures, and cooking utensils. When

considering the type and effectiveness of a

water softener it is important to know what

form of hardness is present.

Calcium Carbonate Equilibrium

This table should be used to compare the pH

of water to its total alkalinity to determine

if the water is considered either corrosive

or depositive. Water samples with a pH and

alkalinity in the deposition zone are likely

to result in calcium carbonate, or lime,

precipitating out of the water and forming

a protective coating inside the lines of a

water distribution system. This coating is

desirable up to a point, as it will help protect

a metallic water line from corrosion. Excess

deposition of calcium carbonate, however,

can eventually clog a water line.

A water sample with a pH and alkalinity

in the corrosive zone are likely to result in

corrosion of metal service lines, tanks, and

xtures. This corrosive effect allows metals

present in your water or lines and xtures

to dissolve into the water. If iron is present

in your water, this may result in reddish-

colored water and red staining of xtures.

These stains may cause the water to have a

less appealing appearance but are not usually

a danger to health. Corrosion can also cause

additional metals, such as lead or copper, to

dissolve into your water.

If you have additional concerns or questions,

or if you are experiencing other problems

which you feel may affect your water,

contact the DEQ’s State Environmental

Laboratory at (405) 702-1000 or (866)

412-3057, or email [email protected], to

discuss your needs and testing options, and

to coordinate additional well water testing.

Additional Information

Visit our webpage at http://www.deq.state.

ok.us/csdnew/index.htm for additional

information.

• Home Water Testing FAQ has additional

information about private wells, well

testing, recommended tests, and private

water treatment options.

• State Environmental Laboratory

Analytical Fee Schedule contains current

pricing for analytical services.

Private Water Well Analysis

Calcium Carbonate Equilibrium

50 100 150 200 250 300 350 400 450 500 600 650

Total Alkalinity

Corrosive Zone

Deposition Zone