Do you monitor your equipment to ensure your customer’s results are accurate?

Yes, our Laboratory Technicians run Quality Control samples on a daily basis. See our certification page.  For more information, please contact our Lab Service Representative by phone (715) 962- 3112or by E-mail.

E. Coli is generally killed at what temperature?

Always cook meat, especially ground meat, until the juices run absolutely clear, pink is not good enough.  It is generally good for the internal temperature of a hamburger patty to reach 160 degrees F to kill all contaminating E.Coli.

How can I tell if I have lead in my water?

Your local public water supply is required to test for lead on a regular basis.  You can call them or ask for the latest issue of their Consumer Confidence Report (this will list all the constituents the supplier must test for and whether or not any contaminants were found).  If you live in an older house, one which may have lead pipes or lead based solder call our lab for specific instructions and special sample bottles to have a sample analyzed.

I have a nitrate result greater than 10 PPM (MG/L). Is my water safe to drink? What can I do to make my water safer to drink as far as nitrates are concerned?

The USEPA and the State of Wisconsin have set a Maximum Contamination Level (MCL) of 10 ppm (mg/L) nitrate for public drinking water supplies and as a guide for private water supplies. A MCL is the highest level of a contaminant that is allowed in drinking water. Nitrates are dangerous especially to infants under the age of 6 months. Some symptoms include shortness of breath and blue-baby syndrome.  Most adults are not overly affected by nitrates.


Water Care Specialist, Plumbers, and Well Installers are all good sources for treatment systems for nitrates. There are several systems available to treat water for nitrates, and these professionals will be able to suggest the best system for your needs.

I have a white (or some other color) buildup around my sink drain and shower stall. Is this coming from my water?

What you are most likely seeing is a build-up of hard water scale. Look in your tea kettle and see if you find the same substance there.  Hard water scale is the result of water precipitating the natural calcium or magnesium compounds from your water.  Water that is hard is not a health threat, it is more an esthetic issue.  Some people prefer the taste of hard water to softer water.  The colors you may be seeing are the iron (reddish) or copper (greenish) also precipitating out of your water.  If you have your water tested for hardness you can interpret the results as follows:


0 ppm Very Soft
50 ppm Soft
125 ppm Hard
200 ppm White buildup will occur
250 ppm Very Hard 

If I wanted to send you a water sample from my home, how would I send it?

E-mail CTL Lab Service Representative and request a water testing kit.  Please let our Service Representative know if you are sending a sample from your home, your business, or a state agency.  There are different requirements for each.

If I’m unable to read or understand the test results, will you have experienced professionals at CTL explain to me what the results mean and answer my questions?

Yes. Feel free to call us at (715) 962-3121 or  E-mail our Lab Sales Representative.

Interesting Facts:

– Non-Detects (ND) – laboratory analysis indicates that the constituent is not found.

– Parts per million (ppm) or Milligrams per liter (mg/l) – one part per million corresponds to one minute in two years, or a single penny in $10,000.

– Parts per billion (ppb) or Micrograms per liter – one part per billion corresponds to one minute in 2,000 years, or a single penny in $10,000,000.

– Parts per trillion (ppt) or Nanograms per liter (nanograms/l) – one part per trillion corresponds to one minute in 2,000,000 years, or a single penny in $10,000,000,000.

– Parts per  quadrillion (ppq) or Picograms per liter (picograms/l) – one part per quadrillion corresponds to one  minute in 2,000,000,000 years or one penny in $10,000,000,000,000.

Is it safe to drink your tap water at home?

If you haven’t tested your drinking water and question if it is safe to drink, contact CTL-Lab by E-mail.  We will send you a CTL  water testing kit along with instructions.

What if I live in another state, not in Wisconsin, and would like something tested. Would I have to get the sample to your company within so many days? And how would I send the sample?

This depends on what type of sample you are sending.  Some samples require overnight mailing whereas other samples do not need to be sent overnight.  The best way to find out how to send your sample is to contact us by E-mail.  Questions regarding how to send your sample and if there is a time limit in getting the sample to CTL will be answered by our Service Representative.

What if I need to send something that needs to remain frozen? How do I send it to you? How would I pack it?

If you mail anything frozen, it is best if you pack it in “dry ice” and send it next day service.  This will keep your product frozen.

A typical food travels an average of 1,100 miles to reach your table.
Source: National Food Processors Association.

What is your office and laboratory hours?

We are open Monday through Friday, from 8:00 a.m. until 4:30 p.m.

What type of clients do you test for?

Animal & Pet Food Manf., Bottle & Breweries, Confectioners, Canning Companies, Dairy Industry, Delicatessens, Drying Plants, Fast Food Industry, Food Distributors & Brokers, Grocery Industry, Fur Farms, Government Agencies & Municipalities, Health Care Facilities, Heavy & Light Industry, Metal Finishers, Pizza Manf., Plastics Industry, Poultry Producers, Public Utilities, Pulp & Paper Manf., Realtors, Restaurants, Sausage Makers, Veterinarians, Water Treatment Companies, Well Drillers, Home Owners, and the list goes on.

When was your company established and how many employees do you have?

For our History, visit our History page.  We currently have 39 employees.  Our Company’s growth has been slow and strong.  We are extremely proud of our employees.  Our Laboratory Technicians are dedicated to their work and to the Company.  Over 70% of our full-time employees have been employed at Commercial Testing Lab for over 8 years.  Commercial Testing Laboratory’s philosophy is to recognize our employees, “they are our Company’s foundation” and to give the highest quality customer service with a personal touch.

Where are you located?

We are located in Colfax, Wisconsin, population 1,100 at 514 Main St.  Colfax in the West Central part of Wisconsin, between Menomonie and Eau Claire.

Who do I contact if I have additional questions?

You can contact our Lab Customer Service Representative via E-mail, phone (715) 962-3121, or fax (715) 962-4030.