Am I missing something here? ND = “Not detected” however they have a number after it. If this isn’t the number of what they detected then what is it? It’s under the “Maximum Contaminant Level (MCL): The highest level of a contaminant allowed in drinking water.”
but it’s still read. If this isn’t the amount “in your water” then what is it? What he was saying that it “didn’t need any action” seems to be a viable and correct thought.
Looking at Altrazine 3 ppb is allowed while they detected .2 ppb. To me that seems like it’s in the water. Although small what other explanation is there?
ND means that it was not detected down to a level of 0.2 ppb, not that is
was detected at 0.2 ppb (if it was detected at 0.2 ppb, the ND flag would not appear next to the value in the table). It’s as simple as that. The only question that remains is if there is atrazine present at some level below 0.2 ppb, what is that level? But I am not going to get into the "If a tree falls in the woods with nobody there..." discussion because it is patently absurd to go there.
The Maximum Contaminant Level (MCL) for atrazine is the federally mandated (Safe Drinking Water Act) maximum amount of atrazine that the EPA has decided is safe for your drinking water. For atrazine the MCL is 3 ppb. Now that is where the problems begin. A lot of people do not trust the EPA and do not accept that 3 ppb atrazine in your drinking water as being safe. Please realize that I do not want to drink water with 3 ppb of atrazine and I am not promoting the MCL concept, I am just trying to tell people how the system works. When I see a ND of 0.2 ppb and an MCL that is 15 times higher than the detection level (3 ppb), it is the end of the story for me and I am drinking my tap water. If atrazine was detected at any level (below or above the MCL) I would be worried, but I have never seen any positive hits, and the detection limit have been low, so as far as I am concerned,; it is not there. However, If they detect atrazine above the MCL (say 4 ppb), somebody is going to pay for the cleanup. Luckily for me, I am the one that gets paid to do the cleanup.
A couple of other points:
You can have high detection limits due to shoddy lab work or, most likely, due to multiple dilutions of the water sample. This can be a real problem. Detections levels are not static and can change with every test. Say you get a ND (4 ppb) and the MCL is 3 ppb. That means that it was not detected at 4 ppb, but the MCL is lower than that. Again, you avoid the "tree in the woods argument" and simply re-test the water until you get actual detects, or non-detects under 3 ppb.
Just because atrazine is on the MCL list, it doesn’t mean that there has ever been a problem with atrazine in the drinking water in your area. The MCL list is what every public water supply system has to test for.
The MCL list is really short. There are hundreds of thousands of other chemicals out there that are not on the list and are not tested for (how does that make you feel?).
A
public water supply has a strict definition. If you live in a small community with a limited tie-ins, or rely on a private supply well, nobody is testing the water.