Well Water Sampling

Well Water Sampling

Well Water Sampling bottles are available at the Bureau for home owners to sample their private wells. New wells and recently repaired wells must be tested for coliform bacteria and have a partial chemical analysis.

Information provided by the Michigan Environmental Health Association:

Printable version (pdf)

Note:

Unless your water well is properly designed, constructed, and maintained, a test result conforming to state standards may give you a false sense of security. A defective well can produce intermittent satisfactory bacteriological tests, but it's continued safety, cannot be assured.

While coliform bacteria and partial chemical testing are good screening tools, they do not detect petroleum products, industrial solvents, heavy metals, herbicides and pesticides. More complex and expensive testing may be appropriate for your site. Your local health department can assist you in deciding what type of testing is needed.

Tips for Water Sampling

Bacteriological Analysis

Partial Chemical Analysis

Tips for Water Sampling:

Use a clean, indoor faucet

Try to avoid threaded taps, leaky or swing-type faucets

Do not use a dirty or contaminated tap

Do not sample through a hose or treatment device

Always sample the cold water

Allow the water to run in a steady stream at least 5 minutes before collecting the sample or until the pump runs.

Do not set the bottle cap down

Do not touch the inside of the cap or bottle

Do not allow the cap or bottle to touch the faucet

Do not rinse the bottle

Maintain a steady low-flow stream

Fill the container to the fill line. Do not overfill

Seal the container as soon as it is filled

Enclose submission slip and proper payment with sample

Transport samples to the lab the same day of collection and early in the week.

Bacteriological Analysis
Evaluation of the bacteriological quality of drinking water is done using "coliform" testing. Coliform bacteria are found in the intestinal tract of warm-blooded animals, surface water; some soils, and decaying vegetation. Coliform bacteria are used as "indicator" organisms. If they are present, pathogenic, or disease-causing organisms, could be present. The DEQ laboratory and many private laboratories use the "defined substrate method". A positive result may indicate that a water supply is not properly protected from contamination. The "defined substrate method" also detects E. coli, an organism that always originates from mammal or bird intestinal tracts. If E. coli is detected, it is more likely that the water supply may contain disease-causing organisms resulting from fecal contamination.

Results of Coliform Analysis
Result Code	This Means
ND	"Non-Detected" - No coliform organisms were detected in the water sample. The sample met the state drinking water standard for bacteriological quality at the time of sampling. (Similar results may be reported as negative; absent; or zero, "0".)
POS	"Positive" - Coliform organisms were present in the water sample. Safety cannot be assured. Collection of a resample to confirm the original result is recommended. An investigation in to the cause of the problem by a qualified individual is advised. (Similar results may be reported as present or any number from I to 200.)
EC-POS	"E. coli detected" - E. coli organisms were detected in the water sample. E. coli organisms are found in the intestines of warm-blooded animals, and as such, their presence in a water supply is considered an indication of sewage contamination. Precautions are recommended in the use of the water supply. These results are the same as fecal coliform positive; however, E. coli results indicate sewage contamination with more certainty.
COMMENTS	Coliform organisms may die during sample holding time (time from collection to testing). The laboratory will comment that results may not be representative/valid if sample holding time is longer than 48 hours. The federal standard for a coliform holding time limit for public water supplies is 30 hours.


Partial Chemical Analysis
The Michigan Department of Environmental Quality laboratory analyzes eight commonly requested parameters in , a routine procedure called a "partial chemical analysis". Below are two tables of these parameters and associated problems. Table I lists three parameters where the USEPA and the state of Michigan have established drinking water health advisory levels for public water supplies. Parameters listed in Table II are associated with aesthetic water quality problems.

Test results are reported in milligrams per liter (mg/l)

Table I.
Test	Good	Satisfactory	Caution	Problem
Nitrate as Nitrogen	ND-3	4-10	Over 10¹	Methemoglobinemia^2,3 (blue baby) esp. infants
Nitrite as Nitrogen	ND-0.3	0.4-1	Over 1¹	Methemoglobinemia^2,3(blue baby) esp. infants
Fluoride	1.0-1.2	0.7-2	Over 2⁴	Low levels are beneficial in preventing tooth decay. High levels may cause mottling of enamel
Table II.
Test	Good	Satisfactory	Caution	Problem
Chloride	ND-20	20-250	Over 250	Taste, corrosion
Hardness	25-100	Over 250 or Less than 25	Over 250	Scaling of water fixtures, soap scum at high levels, corrosion at low levels
Iron	ND-0.2	0.2-).3	Over 0.3	Staining, turbidity, taste, odor
Sodium	ND-20	20-160	Over 160	Taste, special diets may require water of low sodium content
Sulfate	ND-50	50-250	Over 250 Over 500	Taste, odor, scaling in boilers & heat exchangers May have laxative effect especially for new supply user (traveler's diarrhea)
¹ USEPA drinking water standard
² See DEQ pamplet EQC2033 "Nitrate in Drinking Water" 12/99
³ USEPA requires analysis within 48 hours
⁴ USEPA drinking water standard is 4.0 mg/l for the state of Michigan

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Updated September 21, 2005