So, why the low water pressure?
It didn't take long to find the cause. It was hidden, but we found it!
It took some bending, and leaning, and stretching, and camera extending.
But I was able to get a photo of it!
A very, very clogged whole-house water filter.
What's the problem here?
IT'S INACCESSIBLE!
If you can't see it, out of sight is out of mind.
If you can't get to it, regular replacement is difficult at best.
This filter was so clogged water had a hard time passing through it.
And it was particularly noticeable in the shower.
Do the sellers know there is poor water pressure in the house? Of course!
Do they know why? Probably not.
My recommendation: it pays real dividends to understand your house, and all of the many components therein. A house is a big system of interactivity! Things go together and work together. If there is a problem with the water pressure it has to be for a reason. And the reasons could be many! Or any one of many! If there is a known issue, try to figure it out! If you can't, or the professionals you have asked to help cannot, call a home inspector! We are generalists and know how to investigate! And we will.
Jay Markanich Real Estate Inspections, LLC 
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560
Unbelievable! It took me about 20 tries to get this post up. Each time I would publish it most of it would drop off, and then each further time only one more sentence would pop up to get added.
I had to give up and virtually rewrite it. Nothing would save.
Anyone else experiencing this?
Good mornign Jay. Something was wrong here and not just the filter! Seems AR had a clog this morning! Enjoy your day!
Jay Markanich One would think that the homeowner would be more aware of this filter. I can't imagine the leels of contaminants that the owner ha been ingesting!
They must have put it in that spot and then rearranged things later to hide the filter behind the water heater, Wayne. Not good now though!
S&N - I wondered for how many years they put up with the awful pressure! They must have attributed it to "the house." And that filter has to be ripe with all sorts of microbial crap, as you say.
Yummy, good looking stuff on that filter...lol
Who know what's growing in there! I do not drink tap water, but in that house it must have been really tasty, Fred.
Thank you very much, Jay, for sharing your experience and your photograph.
Ugh, but thanks for uncovering the real problem with the low water pressure.
Came over via reblog by Roy Kelley
It was a big yuck, Mary, after I finally found that filter hiding behind the water heater!