Well, if one is to be concerned about that, one probably should not irrigate
at all.

Even if the water/solution you use is free of contaminants, it goes through
your nose, which is always full of all kinds of microbes. Whatever of the
fluid gets into the sinuses is then carrying microbes from the nose into the
sinuses. I think it is not inconceivable that irrigation could cause
infection in some instances, regardless of whether the original solution was
microbe-free. Normal, uninfected sinuses are supposed to be sterile, I
think. However, no one's nose is sterile, it is full of microbes. In
irrigating you are shooting fluid through the nose, thereby getting full of
microbes, before getting to the sinuses, thereby potentially causing
contamination.

Also, your irrigating equipment can never be 100% contaminant-free. Even if
you wash bleach through your Waterpik or other device once a week, as some
recommend, bacteria will grow in it in between. It is sitting there in
between, wet inside, of course it is not sterile.

I guess the idea is though, that it is better to wash out the accumulated
dried-up junk out of the nose (and perhaps partially from the sinuses), that
keeping it clean from that junk will help prevent infection, even though one
might be exposing the sinuses to more microbes through irrigation. (Not all
ENTs recommend irrigation though. I have been to a couple who recommended
against it, although most seem to be for it.)

For someone who doesn't need to, whose nose and throat seems to clear the
accumulated mucus naturally, it might actually be better not to irrigate,
which could potentially spread infection, inflame and dry the tissue, etc.
But for those of us who get clogged with thick persistent mucus sticking in
our noses, sinuses, throats, it is probably better to wash it out, it
certainly feels better afterwards.

Why so argumentative? Do you really want me to give you a number of doctors?
Do you want me to quote names, addresses, phone numbers?

I guess literally I cannot say "most docs", because I have not interviewed
every doctor in the world (or every ENT and allergist), so that I could make
a definitive statement about how many of those who recommend irrigation,
also recommend that the water be sterilized first. But there is no way that
I can make such a definitive statement about "most docs", so I'll take back
that statement. Does that make you feel better?

I'll put it a different way. Having suffered severely from chronic rhinitis
and sinusitis for my whole life, I have been to many ENTs and allergists
about it. Of those I have seen, a few have recommended that I not irrigate.
However, most thought irrigation was a good idea, most seem to advocate it.
Of those who advocate irrigation, not even told me to sterilize the water
used in irrigation.

I have also read extensively about sinus problems, rhinits, and irrigation,
including this NG for years, and except for a few posts here by people who
thought it best to sterilize, the majority of writers (relaying what their
doctors told them) have apparently not been told to sterilize the water.
(See Steven's post, for example.) And one ENT, who seems to advocate
irrigation more than anyone, who invented irrigation devices, and writes
here regularly, Dr. Grossan--I have never seen a statement from him that the
irrigation water should be sterilized first.

So---the consensus of opinion of irrigation advocates, including doctors,
seems to be that it is not necessary to sterilize irrigation water, at least
in countries where the tap water is considered safe to drink. (Please notice
the word "seems" in the preceding sentence--of course I haven't interviewed
all of them.)

We could do a poll here, although that is also unscientific--asking of
readers who have been told by their docs to irrigate, how many have been
told to sterilize the water first?

Obviously though, there are some who do not agree with that consensus, such
as the doctor who told you to sterilize. And it certainly is possible that
you are right--the majority of opinion is certainly not always correct. It
is possible that you will be better off irrigating with sterilized water,
than those of us who do not use sterilized water. I certainly was not
criticizing you for doing so, just saying that the consensus of medical
opinion vis-a-vis irrigation seems to think otherwise. (Which doesn't make
them right. Often minority opinions end up being seen later as correct, and
majority opinions fallacious.) No reason to get mad at me for stating that.

MS wrote:

You might be right. Again, I was just pointing out that while most eye
doctors seem to say not to use homemade saline solution for the eyes, only
sterilized commercial solutions, most ENTs and allergists who advocate
irrigation (at least of those I've been to and read about) do not say that
the irrigation water for the nose should be sterilized first. I was just
pointing out the paradox there, not sure why there is that difference in
what is generally recommended, but that it is there.

Again, you might well be right, that the water should be sterilized. Just
pointing out that that doesn't seem to be the majority view.