This is a long, detailed post about my water problem. I've included all relevant info I can think of.
I bought my first house about 2 years ago, it's a ranch style with a finished basement and a pole building that has a finished area with a small apartment inside. In the last 2 or 3 months our cold water started smelling terribly of sulphur in the house, although not out of every faucet. There is no smell in the hot water, and we have never had this problem before.
We do have well water and our own septic tank. There is a water softener and a tankless water heater in the finished basement, where me & my boyfriend have our own living area. Most of the pipes in the basement are pvc. My mother lives with me and stays on the first level, where in her bedroom the previous owner installed a sink, shower & toilet. My mom has said her cold water in her bathroom sink has always had a slight sulphur smell, but aside from that one sink there was no smell in the house before recently. The smell seems to mostly be in the basement water and in my mom's room, I checked the kitchen sink & don't smell anything from the cold water there or in the other first level bathroom, which is weird. It doesn't make sense that our water would just start smelling badly out of nowhere, unless the previous homeowner was doing something to prevent this smell. I've done research and can't find any info on sulphur smell isolated only to the cold water. Everything I've read is either hot water or both hot & cold.
The only other issue we have had with the water is outside in the pole building apartment there is a standard hot water tank and the water will start to smell of sulphur & get stronger if we don't run the water out there for a few weeks. The previous homeowner said he adds a little bleach to the hot water tank out there whenever it starts to smell, then runs the hot water for a while to flush the tank the next day, and also completely drains the tank to clean it out every spring. I follow his instructions whenever the water starts to smell out there & that takes care of the problem. If I recall correctly it's the HOT water out there that smells.
Here is what we do & have done recently in the house:
-We change the water softener filter as recommended and flush the tankless water heater once a year with vinegar.
-We did change the filter out of a few months back and in doing so we checked the sink water to make sure it was off, when we did this the faucet shot out dirty water & air. After changing the filter we turned the sink back on and let it run for a few minutes to clear the pipes.
-We use the iron fighter salt pellets that the previous homeowner recommended for the water softener.
-This may be coincidence but we did run out of salt somewhere around the time the water started smelling and the softener tank sat empty for maybe a few weeks. Ever since then the water has not seemed soft when I shower, it feels grippy & dry instead of slippery & almost lotion like, even though it's been well over a month since we added the salt.
Anyone have any ideas on what would cause this and what I can do to eliminate the smell? Thanks in advance!