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Environmental Milk and Water Laboratory

Air, food, milk, water, pollen, mold and much more...

Milk and Water Laboratory

(314) 615-8324






Frequently Asked Questions


Services – Microbiological Analysis of Public Drinking Water (including private wells)


Coliform Presence/Absence


Fecal Bacteria (E. coli)


Heterotrophic Plate Count (total “harmless” microbes)

Services – Dairy Product Testing


Petrifilm™ Aerobic Count


Petrifilm™ Coliform


Pasteurized Milk Containers


Antibiotics (Delvo P-5 Pack, IDEXX Snap, Charm SL-BL)


Direct Microscopic Somatic Cell Count and Electronic Somatic Cell Count


Dairy Process Water (certified through state USEPA program)


Homogenization Effectiveness -- Phosphatase (Fluorophos ALP)


Dairy products tested include:

  • Raw milk (cow, goat, sheep)

  • Finished Products (cream, half & half, cottage cheese, flavored milk, pasteurized milk, eggnog)

  • Square

    Other Dairy Testing

  • Water Adulteration

  • Butterfat Content

  • % Solids

  • Accreditations


    FDA - Food and Drug Administration: http://www.fda.gov/


    MDNR - Department of Natural Resources: http://www.dnr.mo.gov/


    EPA - Environmental Protection Agency: http://www.epa.gov/


    Question:  What is the difference between raw milk and pasteurized milk?

    Answer:  Raw milk is bottled directly from the animal. Pasteurized milk has gone through a rigorously timed process of heating and cooling to specified temperatures in properly maintained and operated equipment. Pasteurization kills potentially harmful bacteria.

    Question:  How can I be sure pasteurized milk is free of antibiotics?

    Answer:  By law, all pasteurized milk is carefully tested by dairies for antibiotics (inhibitors of bacterial growth). People who are highly allergic to antibiotics could experience a severe allergic reaction, even death, to milk adulterated with antibiotics. Under penalty of law, dairies must report, and destroy any milk found to contain antibiotics. The Environmental Health Laboratories continuously performs random, unannounced surveillance testing of raw milk to assure that dairies comply with the Federal Pasteurized Milk Ordinance.

    Question:  Does “organic” pasteurized milk differ from regular cow’s milk.

    Answer:  Organic milk has the same composition, nutritional value, and wholesomeness or safety as regular homogenized milk. Rather, it is normal milk obtained from organically pastured cows under the “Organic Food and Production Act of 1990.”

    Question:  Where can I find additional information about milk and milk product safety?


    Question:  Is natural spring water or well water better for you than municipal tap water?

    Answer:  Not necessarily. Municipal water is highly regulated and tested for many contaminants. Municipal water supplies also add low levels of chlorine or chloramines that are harmless to humans, to protect the public from disease causing bacteria, and prevent the water distribution system from becoming fouled by bacterial film. Many municipal water supplies also fortify the water with harmless levels of fluoride, which has protected the public health from complications arising from tooth decay. Natural spring water and well water do not receive the benefit of testing or disinfection, and may have excessive or deficient amounts of fluoride.

    Question:  Can my well become contaminated with bacteria?

    Answer:  Yes! Well water has no disinfectant. Even one microbe can grow and contaminate the well and the entire water distribution system. Simply opening an unpressurized plumbing system for repair, or opening a faucet while the well pump is turned off, may cause back-siphoning of contaminated water and air at the tap resulting in the contamination of the entire plumbing system. You must keep your faucet aerators clean and free of scale, and replace corroded spigots; chlorine cannot reach bacteria hiding there. Keep taps closed during power outages. If draining pipes for plumbing repair or winterizing, the system must be shock chlorinated when placed back in service.

    Question:  What should I do if my well water tests “Unsatisfactory” for bacterial contamination?

    Answer:  Bacterial contamination of a residential well and plumbing system requires disinfection by shock chlorination with unscented household laundry chlorine bleach. Saint Louis County Health will provide instructions along with the test results.

    Question:  I disinfected my well by shock chlorination, but it still tested “Unsatisfactory” upon retest. Why?

    Answer:  A test result of “Unsatisfactory” after shock chlorination may be due to several causes: a forgotten pressurized leg of the plumbing distribution system, heavy sediment in a holding or pressure tank, structural defect in the well casing or seals, and rarely a contaminated aquifer. Roughed-in plumbing, or caped-off dead-leg plumbing left over from a moved fixture must be sealed at the point where they “T-off” from the main line to prevent the stagnant water in them from re-infecting the entire drinking water system. Makeshift air-hammer arresters (dead-end length of pipe under the sink) should be removed or replaced with authentic arresters. We recommend that you make an accurate schematic of your water distribution system showing all taps and distribution points. If dead-end pluming is found, have a licensed plumber remove it.

    Question:  Can well owners correct their bacterial contamination problems with water purification systems, such

    as UV sterilizers, and RO (reversed osmosis) filters?

    Answer:  Regularly testing and disinfection by shock chlorination whenever contamination arises is much more economical. UV systems only sterilize the water passing through them; downstream contamination as a result of back-flow will still require shock chlorination. Water softeners, carbon filters, and RO membranes can become colonized with bacteria. They must be sanitized separately off-line according to the manufacturer’s instructions at the same time you shock chlorinate your plumbing system.

    Question:  To what temperature should I adjust my hot water tank?

    Answer:  To prevent the growth of harmful bacteria, adjust the hot water thermostat to deliver water between 130 to 140°F as measured with an accurate cooking thermometer after the water has reached its hottest at the tap. There is a significant risk of scalding at water temperatures above 140°F. If you have concern about scalding of small children or the elderly, consider having a plumber install a “master thermostatic mixing valve” to cool the water just before it exits the tap used for bathing.

    Question:  Does County Ordinance or the EPA Safe Drinking Water Act protect private well water sources?

    Answer:  Saint Louis County only regulates private wells at the point of occupancy. The issuance of an occupancy permit requires that the drinking water be potable (fit to drink). Saint Louis County Health assists private well owners in meeting their personal responsibility for the ongoing safety of their drinking water by providing testing, disinfection instruction, and technical advice. The EPA Safe Drinking Water Act regulates only public drinking water systems, which are defined as publicly or privately owned water sources that serve at least 25 people or 15 service connections for at least 60 days per year.

    Question:  How often should I test my well water?

    Answer:  Saint Louis County Department of Health recommends that you test your well water yearly, or after plumbing work, power outages, flooding, or you notice a change in water quality. If your water tests “Unsatisfactory”, The Environmental Health Laboratories will provide you with instruction on disinfecting your well and distribution system by shock-chlorination. Your water is safe to drink when it tests “Satisfactory”.

    Question:  Where can I pick up a sample bottle for water testing?

    Answer:  Sample bottles and instructions for taking water samples may be picked up from 8:00a.m. to 4:30p.m. Monday through Friday at the following locations:

    Main Office

    Environmental Health Laboratories

    6121 North Hanley Road

    Berkeley, MO 63134

    (314) 615-8324

    North County Office

    21 Village Square

    Hazelwood, MO 63042

    (314) 615-7469

    South County Office

    4562 Lemay Ferry Road

    Saint Louis, MO 63129

    (314) 615-4027

    West County Office

    74 Clarkson/Wilson Center

    Chesterfield, MO 63017

    (314) 615-0929

    Question:  Where can I find data on Saint Louis County’s municipal drinking water?

    Answer:  Public water supplies are required to provide annual Consumer Confidence Reports to their customers. Missouri American Water Company customers receive their reports by mail, or you may view the report at any time on the Internet at: http://www.amwater.com/moaw/

    Question:  Where can I find more information on water quality assurance?


    EPA Ground Water and Drinking Water:


    EPA Safe Drinking Water Act:


    National Well Water Association:


    EPA Private Drinking Water Wells:


    Water Quality Report for St. Louis County:


    St. Louis County Basic Water Quality Summary: