DLR: Good News and Bad News

Being new to the blog biz, I made my first mistake on my first blog: I inadvertently cut off the final few sentences. But that gives me the opportunity to expand on that missing topic in today’s blog.
The Detection Level for Reporting (DLR) is a term of art in water regulation. It addresses the physical limitations of our analytical equipment in the laboratory. Yes, there are limits to what our friends in the nice white coats can find! I think of the DLR in these terms: The speedometer on my car goes to 120 mph; what would the speedometer read if I were traveling at NASCAR speeds? 120 mph! There is a physical limit to the upper end of the speed monitoring device in a car.
There is also a physical limit on the lower end. If I were to inch along at less than 1 mph or so, my speedometer would still read 0 mph – despite the fact that the car was in motion.
The same is true for lab instruments. There might be extremely low levels of a substance in the water, but the level is so low that the instrument cannot detect it. What is the lowest level at which an instrument can deliver a reliable, accurate result? The DLR. This number tells us how sensitive the analytical method is. That’s the good news.
The bad news is that we may confuse our customers with the DLR. We are precluded from putting a zero anywhere on our water quality reports. If we find nothing, we report ”In many cases, the result is exactly the opposite of the intent: instead of clearly informing the consumer that the water is safe, the consumer takes one look at the report and gives up.
So that’s the good news and the bad news of the DLR.

Steve McLean

One Response to DLR: Good News and Bad News

  1. avatar Kristina says:

    WHAT UP STEVE–NICE JOB TEACH –HOPEFULLY THIS WILL TURN INTO A GOOD RESOURCE SIGHT FOR INFO AND HELP–THANX AGAIN .. SO FOR THE 1ST QUESTION ANY CLASSES COMING UP YOUR GOING TO TEACH? OR COULD YOU POST AN AWWA SCED OF CLASSES FOR RANCHO AWWA- AND JEREMY AND I WERE WONDERING IF YOUR GONNA GIVE AWAY FREE PIZZA COUPONS FOR FRIDAY.— ERNIE V

Leave a Reply

Your email address will not be published. Required fields are marked *

*