Bellevue's testing was performed to their standards for inclusion for hospital usage. NYU and the Doctors accepted by design alone. So, to answer your question, we did not specifically employ an outside testing facility. If we did, what would the testing procedure be? Test it closed for 4-6 weeks? Test is after being opened every day from showering? You see, it's quite a bit more complicated by design. Our theory is simple and accepted. Anything the patient/consumer can do with ease on a daily basis to reduce/prevent/ameliorate a known risk is a step in the right direction. If your pipes are free from NTM completely and there is low levels in your ground/well water supply to your home, the stopping points are a place of accumulation. That includes every fitting in your plumbing system, every 45 degree elbow, the porosity there within. When you say multiple taps, are you referring to sink faucets? Water for drinking? That is another chapter for discussion. What appears to be the main focus of this thread are Shower Heads which are not only a major culprit in the stopping point and accumulation of NTM and dozens of other harmful bacteria but, a highly publicized and tested transporter. I spent years cutting open traditional shower heads after my mother came down with NTM which was confirmed to be in her shower head as tested by her doctor after I removed it. When you see what I have seen in virtually all enclose shower heads including those in my own home. Regardless of manufacturer, they all basically fail by design as they are all wet, dark, enclosed, have complicated internals made from porous materials. A virtual petri dish that you cannot see inside, you cannot clean inside, you cannot confirm free of NTM or any of the other 50 plus pathogens on a daily basis. No other company of all major household brands has been asked to test for NTM or anything else for that matter. Please feel free to cut anyone you wish open to understand what I am saying. I encourage all. Shower Clear is NOT a cure for NTM, it is merely a step in the right direction in order to take a known cause in this complicated condition and dozens of others out of the equation. As an engineer, large problems get fixed one way. One step at a time. There is no magic wand to fix everything at once. Why do we wash our dishes after every meal? We wouldn't think to let any food remain and use again the next day yet, we take for granted a century old design in a shower head must be fine when in fact it's not and cannot be cleaned like your dishes. I changed that with Shower Clear. I hope this helps. I have over a hundred pounds of documentation including a down play by major manufacturers in public document. I offer and welcome Mayo Clinic a complimentary sample if they would like to test on their own. I hope this helps. It's really not that complicated.