Bath Towels Have a Stinky Metallic Smell?

OK I realize this question has been on going on here for years, but here's what I've got. About a 9 months ago our bath towels began having this smell, almost like a pee smell or a strongly metallic type smell. It is absolutely the worst thing to pop out of the shower and bury your face in a towel that smells that way.

My disabled dad said he could smell it in his clothes and beard and as soon as one of his face towels got wet. (These face towels are kept in a separate 1/2 bath in his room, but there is only one full bath in house.) The smell on him is confirmed by a 3rd party. My clothes I don't smell until I break a good sweat, but even then that smell is different. It is more of a musty smell which I know is from having one or two sweaty shirts at the bottom of the pile and then forgetting and not washing for 3 or 4 days. (I am single so its just me doing just my laundry.) My disabled mother has no smell on any of her clothes, but confirms that yes the towels stink. It is not the white ones and I assume it's because they are bleached.

Now a little more history. 1 year ago my father fell ill and came to live with me. He demanded a new septic system for whatever reason which was a disaster from the moment he picked up the phone to call an installer. Needless to say 3 weeks later I noticed the ground was really wet at the back door and so I pulled off some skirting to have a look and wow there was three weeks worth of raw sewage under my house. (No exaggeration, 2100 square ft of 3-4 inches of sewage was not going into tank, but instead blew a clean out off underneath because it was barely on cause it was supposed to become a vent pipe, but was forgotten. The main line was clogged and so the sewer went to the path of least resistance.

I fixed it and dug a trench to drain the sewage only to have it happen again, but this time it pulled the washer drain pipe out of the wall from underneath because of all the weight of sewage again backed up and that pipe runs the full length of the house. So I ran the washer drain and bath tub to its own line and it goes out to the field. (I live really far out in the country and seeing it is classified as gray water the health guy said it was fine.) This reduced the stress on the septic and the leach field and hopefully stopped the clogging.

I left all the skirting off the house over the summer and fall to air it out. There were no more problems. A few months after that we got the smell in the towels. So during the septic issue I had to replace wax rings because of the stress that the 3 week clog put on them. When I did I noticed that the subfloor was black and wet from the wax ring leaking. I couldn't replace it because there was a lot of tile that I just put down over both bathrooms so I soaked it in bleach let her dry for a few and hoped for the best.

So when the smell arrived in the towels I thought it may be from the wood cause of where the towels were stored they could possibly be getting some air from an access shaft or tunnel that was used long ago to retrieve dirty laundry since it wasn't sealed off. When I went in to seal it, yes you could smell the same smell. So it seemed. So I went at it caulking all shelves in the linen closet, all drain holes in the vanity, all supply line holes, all bathroom trim, tub drain, and all.

Still the towels stunk. So we washed a load at my grandmother's and they came back with no smell. I work as a service technician on home appliances so I knew this was no fabric softener or stagnant water smell. Those will gag you. This one just makes you crinkle your nose the whole time, but still unpleasant. So I replaced the water heater. That anode rod inside the water heater was way past deteriorated it was gone completely. You know the one that they put in there that is supposed to keep it from smelling because whatever reacts with the rod instead of reacting with the tank. I am not sure of the chemistry there, but none the less. Oh, I also replaced this because I first drained the tank and was gonna rinse it good and when I drained it the last several gallons were black and it emitted the same smell of pee or metallic smell. It is not a raw sewage smell, but more like a treated sewage kinda or like on of those public restrooms where you walk in and it looks like somebody did the hokey pokey while trying to pee and nobody cleaned it just let it dry, but mixed with a copper penny smell. The rinse didn't help my smell. Maybe a little. So I replaced the tank with a new high dollar one. And it seemed like that worked. Conveniently the washer went out soon after and so I replaced it. My dad got better so he moved back to his home, but not long before he left the smell slowly came back. Some towels, the worst ones never really lost the smell. But the house had begun to smell and it's gone and not came back. But some towels do. Now I don't know if they are new or maybe some of the ones that didn't get so smelly the first time so we saved em or what, but they have the smell and it seems to be slowly getting worse in them.

So I got a new tank, new washer, sealed leaks, and any drain near the towel storage or washer is run to a over land flow system with no smell and completely separate from septic. My grandmother is on same water system where we washed that one load to see if it was our water source. I have lived here for 20 years and before that my great grandfather live here for like 80 years and this is the first time this has happened. What could it possibly be? I don't wanna cover it up or take the smell out so much as find the source and fix it.