A whole house well water filtration system diagram is really a statement about sequence. Water arrives from the well, and every stage after that either protects the one behind it or depends on the one in front of it, so the layout is not a matter of taste. Read any diagram left to right and ask what each box is protecting.
From the well to the pressure tank
The left hand end of the diagram is the submersible pump, the pitless adapter where the line leaves the casing below frost depth, and the run into the house. Then comes the pressure tank, the pressure switch and a gauge, plus a well head sample tap. Nothing filtering belongs before the pressure tank, because the pump needs to see unrestricted flow and because a clogged filter on the suction side is how pumps get damaged. Every treatment stage begins downstream of the tank.
Sediment, then oxidation, then media
First after the tank is sediment removal, sized for the grit the well produces, because sand chews control valves and blinds every media bed behind it. Next comes whatever converts dissolved metals and gas into particles: an air injection head, a chlorine or peroxide injection point with a contact tank, or a catalytic media that does the oxidation in the bed. Then the filter tank that catches what the oxidation produced. This is the block of the diagram that changes most between wells, and the water test dictates it.
pH correction and the softener
If the well is acidic, an acid neutralizing tank sits before the softener, because low pH attacks copper plumbing and undermines the iron chemistry upstream. The softener then goes after all the iron and sediment work, never before it, since oxidized iron fouls the resin bed. Penn State Extension puts recommended maximums at 0.3 mg/L for iron and 0.05 mg/L for manganese, and describes the narrow window in which a softener alone can handle dissolved iron, which is the reason the iron filter comes first.
Disinfection last, then the tap
Ultraviolet is drawn at the right hand end of the diagram, immediately before the water goes to the house, because it needs the clearest water in the system and offers no residual protection. A chlorine feed appears instead near the beginning with its contact tank and a carbon filter afterwards, which is why the two disinfection strategies sit at opposite ends of the drawing. Finally a point of use unit at the kitchen sink, usually reverse osmosis, handles the last fraction that whole house treatment does not.
The details a good diagram also shows
A proper layout marks a bypass loop around the whole train, isolation valves either side of each stage, sample taps between stages so you can prove which one is failing, drain lines with air gaps for anything that backwashes, and unions so a tank can come out without cutting pipe. It also shows which taps are deliberately left untreated, typically outside spigots. Our well water testing guide covers the panel that tells you which of the middle stages your particular well needs.
Questions people ask about whole house well water filtration system diagram
What order should well water filtration components go in?
Pressure tank, sediment, oxidation and iron or sulfur removal, acid neutralizer if needed, softener, then ultraviolet, with a point of use unit at the sink. Each stage protects the one behind it.
Should the softener come before or after the iron filter?
After. Oxidized iron fouls softener resin, so iron is oxidized and filtered out first. Penn State Extension describes only a narrow set of conditions in which a softener handles dissolved iron on its own.
Can a filter be installed before the pressure tank?
It should not be. Restricting flow on that side stresses the pump and a blocked filter can cause short cycling. All treatment stages belong downstream of the pressure tank.
Why does UV go at the end of the system?
Because ultraviolet needs clear water for the light to reach organisms, and it leaves no residual. Placing it last means everything that could block the light has already been removed and nothing downstream recontaminates it.