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Now we will discuss Bacteriological Sampling.
Now...diseases are transmitted by unsafe water. Some of the diseases that are transmitted by unsafe water is typhoid, paratyphoid,
bacillary dysentery, amoebic dysentery, cholera, cryptosporidiosis, and giardia.
The last two being chlorine resistant. So it is very important in order to test the water for diseases
in order to disinfect to properly treat the water to a quality for human consumption.
Now, is it difficult to test for pathogens or do we test for all possible pathogens.
When you think in one drop of water there are millions of bacteria and out of that millions of bacteria, only a small portion are pathogenic.
Pathogenic means disease causing organisms. Very difficult to test for very small out of millions.
So we don't test for all possible pathogens that are present but what we do do is identify an indicative organism group
and once this group is positive or present then it's more like all the other pathogens may be there also. Birds of a feather, flock together.
So the indicative organisms that we use is the total coliform group.
Within the total coliform group, we have the fecal component and we have the non-fecal species.
Of the non-fecal species these are the total coliform bacteria. The fecal species, e-coli being more specific because it indicates
it's from the intestinal waste of warm-blooded organisms there.
When there is a positive coliform present then there is an indication there is a risk of disease.
Generally your coliform group does not cause disease but again it indicates that there may be pathogen bacteria present.
This is a very critical responsibility of water operators to collect the bacteriological samples.
Now first of all you want to make sure that you're collecting from representative sites. Your site should be active and not dormant.
Also you want to make sure you're collecting in a very sterile container which we will discuss a little later.
You want to make sure that you are determining the number of samples based on population
and that you have a written sample-siting plan available.
With the written sample-siting plan you want to make sure it's representative of your system.
So get your distribution map, look at all your looped areas, your dead ends, your size of mains
to make sure that you're collecting again reresentative of the entire utility and not just at the location near the treatment itself.
So the population will determine the number of samples to collect. For instance,
if I'm serving from 25-1,000 individuals that's one routine sample collected per month.
If I have up to 3,300, I'm collecting at a minimum 3 samples per month.
Now your state or territory may require you to do additional samples or increase frequency at their discretion.
Some of the things you want to make sure that you keep in mind when selecting your sample sites, there are a few areas you want to avoid
and some of the sampling points you want to avoid are the swivel-type faucets. You know one valve for hot and cold, not a good sampling site.
If your faucet has leaking packing material around it, again not a good sampling site because of cross contamination.
Make sure you're collecting or pulling from faucets that are not too close to the ground with lots of vegetation around them.
You want to make sure again, with your faucets, that they are smooth on the inside and they don't have the internal threads there.
And if your faucet has an aerator, please remove prior to sample collection
Now the ideal sampling site is to actually tap in directly into the main whereas we know we're
getting the water representative of the treatment process and not our customer plumbing.
We want to make sure we obtain sample containers from the lab. These containers must be sterilized.
If they are older than six months, toss them out, cannot use them.
If the seal is broken, obtain a new container in order to collect your sample.
Within this bottle there is sodium thiosulfate for neutralizing the chlorine; very important.
It's a bacteriological biological analysis we're about to perform and chlorine will impede or mess the sampling up.
Make sure you're sampling from a designated site. Do not take samples on a windy or rainy day and make sure again no leaky faucets there.
So I'm at the sampling site, you want to make sure the first thing you do is flush the line.
Make sure again you have chlorine residual there and that we're actually getting water from the main. We're going to test for chlorine.
If chlorine is present, excellent. We can proceed.
If no chlorine is present you want to make sure you flush some more
in order to make sure you have freshly chlorinated water into that area you're about to pool.
Next go ahead and cut the water off, flame and disinfect the faucet. You can use alcohol,
hydrogen peroxide, or a 50/50 bleach solution for disinfection.
Next, remove the cap and when removing the cap make sure you're not exposing the cap to additional contamination
so keep it turned downward there. Make sure you're not putting your fingers within the water stream to possibly contaminate the sample.
Go ahead and fill it up 100 ml or better, do not over fill the sample bottle because again
there's only enough sodium thiosulfate to neutralize 125 ml of chlorine that may be there.
Cap the sample. Put it in the cooler and keep it cool on ice until it arrives in the laboratory.
You must get the sample to the laboratory for analysis within 30 hours.
Complete the sampling form. Make sure you're putting the location, the date, the time, the person who collected the sample.
The chain of custody is very critical for proper documentation. Please mark it distribution sample also and get it to the lab within 30 hours.
Once it's in the lab, the lab will set the sample up in order to test for microbial contamination.
Within this test, it will come back positive or negative if coliform is present.
If coliform is present, we'll have blue raised dots on the media within a 24-hour period
So, what happens? If it's positive, you must collect at least three repeats for every one positive sample.
You must go back to the original site within 5 connections upstream and within 5 connections downstream.
What are we trying to prove? If the problem is with the distribution system or the actual sampling point.
What does a positive sample look like?
As you can see, we have blue colored dome colonies formed for positive coliform there.
When it's positive and you're collecting your repeat samples, all samples must be collected within a 24-hour period.
If I have only one sampling point, I can collect 4 consecutive days or from the same tap on the same day.
Now, system violations. Monitoring requirements, I exceed my MCL if the routine samples are not submitted
If I'm required to collect 3 samples and I only collect 2, that's a violation.
If I'm collecting more than 40 samples and greater than 5 percent are positive, it's an MCL exceedance.
If I'm collecting less than 40 routine samples and I have more than 1 positive, that too is a violation.
Acute risk will occur if I have any combination of fecal or e-coliform positive,
that constitutes an acute violation which means now I have 24 hours to get that information to my public to ask them to boil their water.
Any total coliform followed by an e-coli is an acute violation. I notify the state first within 24 hours.
I notify my consumers within 24 hours by television, radio, hand deliver or any method that's approved by the state or territory.
Within this notification may be again another notice that tells the consumer boil the water for drinking,
for cooking, for bathing, at least a rolling boil 1-2 minutes.
Now, monthly MCL exceedance will occur if I have a positive total coliform followed by a positive total coliform.
Remember these are the non-fecal species.
EPA says I have 30 days to notify my public when there is just a monthly MCL exceedance
I still will notify the state within a 24 hour period.
In addition, the following month I will be collecting 5 additional samples.
Are there exceptions to the rule? Can a positive coliform be removed from your sampling? And the answer is yes.
How can you have it removed? If your routine sample is positive and all your repeats are negative
and you can prove why that positive is not representative of your distribution system, EPA says you can request invalidating the sample
and have that removed.
In addition to that, reduced monitoring may also be possible if the system has no history of coliform contamination.
That, too, must be put in in a request form to your state.
Other tidbits for bacteriological sampling - worksheets. Very critical. Helps us to insure that the correct number of samples are pulled.
It also helps with the organization of sampling, repeats and followups. It insures that you're always on the straight and narrow
and you're doing what is necessary in order to prove the quality of the water in your distribution system.
This concludes bacteriological sampling and analysis. Thank you.