Borehole help in diagnosing why radical change in water quality

We purchased a property in Perthshire in Dec 25 which had a Borehole installed Nov 2024 due to the former spring becoming unreliable. all water tests good in 25.

Basic set up of arsenic tank and cartridges at the borehole, water pumped 100 m to the house storage tank and then transfer pump through UV and further cartridges to attic tank and gravity fed.

Serviced and water tested at kitchen tap June 26 - Aluminium 354 and Iron 220

Retested July 26

raw borehole  Aluminium 936 Iron 536

After treatment Aluminium 1793 Iron 1441

Consultation between filtration installers and manufacturers advised retest at different points of filtration. Installers first ran the borehole direct into our run off for 40 mins and it turned orange.  Advised to keep running it until it went clear.  This took several days and then they tested.

The results confirm that virtually all the iron and aluminium is particulate rather than dissolved.

The raw borehole water has total aluminium of approximately 1,350 µg/L and iron of 830 µg/L, whereas dissolved aluminium is below 8 µg/L and dissolved iron is below 7 µg/L.

Being advised by filtration company to add Turbidex backwashing filter before arsenic tank and ultrafiltration at the house.  Total cost £8250exc vat

My concern is they seem keen to make it clear that they cannot guarantee this will fix the issue.

Also nobody can give explanation as to why the levels seem to be going up after filtration other than a suggestion that the water is fluctuating in its make up and just so happens that both times it surged in higher particulate when tested after filtration or it was inadequately flushed. This seems a stretch that its gone up after filter cartridges in two separate tests?

So a very expensive option to run what they are saying is a filtration trial.

If it’s required I will of course go for it.  We then have multiple issues with needing extra backwash capacity and where to run of the chlorinated water as well as the pressure we will be left with after all the filtration.  Hoping to put a whole house booster on with pressure vessel so not sure if this will work with this new ultrafiltration system. This is secondary however to trying to get clean drinking water which we have now not had for 4 months!

My question is could there be a failure somewhere in the borehole itself that means more sediment or the like getting in or stirred up and will all the new filters simply become overwhelmed.  We can't seem to get a straight answer on this from the installation company who keep repeating no its the supply water that changed. Is the borehole pump going to be getting choked up with the change in the level of particulate or is it common for them to run in high particulate water.  Do Aquifiers frequently change in this way in a short space of time just due to natural changes and require a change in filtration? Is it common to refuse to guarantee a £10k install despite all the testing that has been done.

There has been no change to our close 2 neighbours water quality and no obvious changes in the land around us.

Help! have not had a private water supply before and had hoped we would get a few years on such a new instal before expenses like this came in.