A filtration diagram is mostly about sequence. Each stage exists partly to treat the water and partly to protect the stage after it, so the order is not arbitrary and getting it wrong produces a system whose expensive components fail early. Reading one properly means asking what each box is defending.
The order and why it is that order
pH correction first where the water is acidic, because iron oxidation and several media depend on pH. Then sediment removal, a separator or backwashing tank on gritty water, so grit never reaches anything after it. Then iron and manganese treatment, since oxidized iron fouls softener resin. Then softening. Then carbon for chlorine, taste and organics. Then ultraviolet last of all, immediately before distribution, because it only works on water everything upstream has made clear.
Where it connects to the house
The train goes on the incoming main after the meter and main shutoff and before any branch, so every outlet is served, and always before the water heater, since a heater fed untreated water scales and stains from the inside and no downstream filter recovers that. The one branch usually taken ahead of the treatment is the outside tap for irrigation, since garden water does not need treating and consumes capacity for no benefit.
The valves a good diagram shows
Isolation valves either side of each stage, so one component can be serviced without draining everything. A bypass loop around the whole assembly, so the property keeps water during a service or a failure. Pressure gauges before and after the filter bank, which is the only honest way to know when a cartridge is spent rather than guessing on a calendar. And drain connections with air gaps for anything that backwashes or regenerates.
What diagrams leave out
Space, which is what defeats installations in practice. Clearance below each housing equal to its sump depth, or cartridges cannot be withdrawn without cutting pipework. Headroom above media tanks to service the control head. Floor loading for full tanks. Access to the drain and enough fall to it. And frost protection where the equipment lives somewhere unheated. Measure at the intended position before ordering anything. Our well filtration guide covers building a train from a test result.
Questions people ask about water filtration system diagram
What order do filtration stages go in?
pH correction, sediment, iron and manganese, softening, carbon, then ultraviolet last, immediately before distribution.
Where does the train connect to the house?
On the incoming main after the meter and shutoff, before any branch, and always ahead of the water heater.
Which valves should the diagram include?
Isolation valves either side of each stage, a bypass around the whole assembly, pressure gauges, and drains with air gaps.
What do diagrams usually omit?
Space: clearance below housings, headroom above tanks, floor loading, drain access and frost protection.