The first thing to do is get a comprehensive water test from a certified lab. If you use a local lab they should be familiar with what additional tests would be a good idea.

At a minimum test for hardness, pH, TDS, sodium, iron, manganese, arsenic, nitrates, and bacteria. I'd want to have the lab identify the black sediment.

With those test results and...
# of people in the home
# of bathrooms
are there any water hogging appliances like a Jacuzzi
what is the water supply line diameter at the softener

The correct softener size can be calculated.

After doing some research and talking to a lab I believe what I have is Iron bacteria. I am having the water tested for it. If the test comes back positive then I will be reassessing my filtering needs altogether. I will follow up here.

Just received results on the Iron Bacteria: 500 cfu/mL. A plumber suggests I install a chlorine injection system in front of my pressure tank to kill the Iron bacteria and then a Terminox filter after the tank to remove any iron. The house has 2 1/2 baths; 4 people. Incoming pipe diam from the pump is 1.5". I welcome any suggestions from the experts.

Where did the sample come from that indicated iron-reducing bacteria? Have you tried chlorine shocking the well? You mentioned that your are finishing up the house - is this new construction with a new well?

Plumbers, with rare exception, know very little about water treatment. Rather than a plumber, you should be talking to water treatment folks.

The sample was drawn from a finished bath and sent to a lab in the area. This is new construction with a new well. Still finishing some aspects of the house prior to moving in. I have not tried any means of treating the water. Just doing research on what might be wide to try. I appreciate your help (and the advice on not starting a new thread).

Are you sure your well casing is deep enough? We had a bacteria problem on a new build/new well and it turned out the well casing was not deep enough. Once it was extended, the bacteria problem went away. Our county office was very helpful.

Casing went down 58 feet which is the depth of the bedrock. I dont think that is the problem. In fact, I may not have a problem altho the presence of a stain on the toilet bowl as well as what appears to be bacterial growth in the tank seems to indicate something is amiss.

One more question: How long did you run the water before taking your sample?

I ran the water for about a minute before filling the sample vile.

The groundwater system I worked at has a big problem with iron bacteria. The old well pipes and casings were steel and every few years they would need to be replaced due to holes and clogging. Every year we had a professional well company shock the wells with EPA/USF approved chemicals and flush for a couple days. They eventally had to rebuild the wells with stainless and pvc components which helped a lot on the water treatment part. Are any of your parts carbon steel or iron?

Also, it's common for there to a high amount of manganese in groundwater that has a large amount of iron. If the black stuff if somewhat grimey and slick it is very likely manganese. Red/brown is almost always iron. Potassium permanganate is what we used for iron/manganese controls then we aerated the water before filtration.

But to second as stated before. Get the water tested by a lab that is certified to test water. Not by a pool store, plumber, or anyone trying to sell you anything.

It would probably be helpful to take some samples directly from the well before it comes into contact with any part of the plumbing system.

The well is new. It uses PVC casing and the pipe from the well head to the house is PVC. The water has been tested by a lab altho I did not have it tested for manganese. Each test costs $50 so I am reluctant to run a battery of tests unless I am relatively certain of the need.

Given your stated conditions, I would look into a chlorine injection system, followed by a contact tank, then a media-bed filter. This will have the dual effect of killing the bacteria as well as removing the iron.

You started this thread wanting a softener. Is that still something you are considering, or have you decided on just the iron/iron bacteria treatment?

I think, given what I know now, that a softener probably is not required. However, if after installing such a system as you recommend, I find the water too hard I can always add a softener. I thank everyone for their insights and if there is anything else you want to add please do.