Should Water Sediment Filters Come Before or After Water Softener?

Question

My question is:

In a water system, should water filtration come before or after the water softener? Edit: or even before the pressure tank?

At my cottage, we have a shallow well with an above ground jet pump. The "water system" is housed in an external pump house (basically a shed). The current flow is as follows:

well --> pump (pressure switch is on the pump) --> pressure tank --> water filters --> softener --> heater --> cottage

Water is pumped out of the well by the pump, then next is the water pressure tank, followed by three water filters (two for rust - different particle sizes, and the third is a "smell and taste" filter). Next is the water softener, then the water-heater inlet (where hot and cold splits) and then into the cottage from there.

It has been this way for three years, and no issues, but recently a plumber mentioned he would always have water flowing into the softener first and THEN through the rain fresh filters (opposite to what I currently have). I asked why and he couldn't articulate it other than it was what he had always done/was taught.

Based on the above components, is my current flow correct or are they in an improper order?

NOTE: we have incredibly rusty water... so rusty that without filters and softener, it would completely clog faucet aerators and shower heads after a few months. The pump is unhooked and drained before each winter, and every year it is seized from rust by the time I go to hook it up in the spring.

A few photos to give you an idea of what the water filters are:

Answer 1

I'd prefilter (based on your other question calling this "ridiculously rusty water") ahead of your replaceable cartridge filters with a cleanable/dumpable screen filter (a vortex with a permanent screen in the middle and a catch chamber and dump valve on the bottom) between the pump and the pressure tank. That type of filter works best with fast flow.

In fact, I do on my own system. Put a bucket under the valve and it removes what's caught in the chamber and blows the screen clear (since the pressure tank is on the "clean" side of it.)

The cartridge filters will be better on the upstream side of the pressure tank (where they are now) since faster flow does not help them work better.

As for the plumber, sounds like "future plumbing work guaranteed" to me. So the plumber might like it that way - having fought a water softener with valves that got funky in a "rusty water house" I'm not in favor of dumping rusty water into one unfiltered.

Edit - if you WANT to rearrange your filters you could make some small argument for putting the activated carbon (taste and odor) after the softener, but it's a small argument and probably not worth the hassle. You might want to take off the "watering gardens" water before it and the softener, though.

This is the type of filter I use - "spin-down" or "vortex" or "sediment trapper" with a sediment trap below the actual filter screen. water enters and is spun around the outside at high speed, then drawn through the screen - a fair bit of the junk slides down the walls where it's thrown & falls into the trap and thus is not clogging the screen.

I use the 200 mesh (finest) stainless steel element, as I'm dubious about the longevity of polyester screen elements, which go finer. And I very specifically put it between the pump and pressure tank, which is not where the manufacturer suggests, but it makes the best engineering sense (since having the tank upstream means that dumping the sediment trap automatically backwashes the filter, & it does not have to be opened in normal circumstances.) If the water shed is not dark you might want to give it a box or a black bag over it to keep it from growing algae. Look occasionally and dump what it's caught.