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We are looking to standardize a procedure for disinfecting the spigot of our permanent sampling stations. There are pros and cons to each of the methods we are considering. What are the methods that work best for you?
Best answer:
Alcohol is the best universal disinfectant for this application due to practically instant disinfection. Sodium hypochlorite (12%) is okay but needs some contact time. Heat/flame is probably the most efficient but as noted earlier can be easily "overused". Improper disinfection of sampling spigots can lead to additional costs for re-sampling, so it's important to get it right the first time. Pre-packaged disinfecting wipes may generate waste but they are sterile and do a great job of disinfecting the area. When I was an operator, I used bottled rubbing alcohol and lint-free wipes (eg. Kim Wipes) - a fresh wipe was used for each sampling location. In my opinion, the importance of sterility trumps the concern over solid waste so any standard procedure should ensure first and foremost that the sample spigot is properly disinfected and repeats are not required.
I just poured it onto the wipe at that time, but a spray bottle would be an excellent idea.
i am also interested in this. we currently use 12% hypo in a spray bottle, but the spray function gets inoperable quickly. We also from time to time use a torch for disinfection but some operators get a little zealous and melt the equipment.
I was also wondering if anyone is using alcohol swabs and how is that working for them? They seem to cause a lot of waste with having to tear open those little packages and then having to dispose of the wipe each time. Does anyone use an alcohol spray?
Nalgene squeeze bottle (that can be used upside down) 12.5% Cl2, squirt inside ant out let sit for 3-5 minutes then flush sample tap for 3 minutes, you can also flame it with propane torch, But I wouldn't only use a flame.
When you are using the hypochlorite, are you not having to deal with corrosion on your fixtures?
If you have concerns about fixtures corroding I would just rinse it off after the samples are collected...
We use a combination of 12% hypochlorite and torch. We flush the sampling port for a minimum of 4 minutes, turn off the port and thoroughly wet the port with the hypochlorite solution. We then flame the port until the solution is dry and then rewet the port. We then take the sample. We have not had any false positives in over 20 years of using this technique.
I use a propane torch for the tap itself, but an issue we've had with inexperienced operators that everyone should be aware of is personal sanitation.
Wash your hands, use hand sanitizer, wear gloves, and for BACTs only open the bottle when you are ready to fill, only long enough to fill it, seal it properly, and DO NOT touch it anywhere near the cap or opening, and do not even breathe towards an open sample bottle.
In my 2+ years of operation every coliform positive result we've had was directly traceable to improper sanitation of the sampler or the tap, but that doesn't get us back the time/effort/$ lost to mandated resampling.
Like so many, many things, the root cause and concern is proper training.
Thanks for this reminder. It's amazing how easy a micro sample can be contaminated.
Up until now I have been flaming the taps for my Bac-T's. I just started using a Lab rinse bottle with alcohol (70% Isopropyl). Will see how that works out. I hope it works as I am tired of fooling with a propane torch.
I had a false positive once due to sediment buildup in the finish water sample tap at our plant. Took the faucet apart and couldn't believe the buildup in it. A nuisance as I had to find sample sites up and down from the plant, how embarassing.
I have one sample site where the customer has one of those backflow preventer things on the end of the faucet. I've halfway melted the plastic parts inside it and am very tempted to remove it. I don't think they even know about it as most folks will go with whats ever there and not think twice about it. Alcohol won't reach inside it very well and I feel I'm asking for a bad sample by leaving it.
Down here in Georgia we do have a lot of spiders, ants and other bugs which I chase off with the torch,as well as clearing spider webs. I guess I can squirt them with alcohol and watch them scurry off.
Thanks meier4995. Did you use the rubbing alcohol in a spray bottle or just pour it into the wipe?