Two days in and the filter is brown with dirt. At this rate its going to muck up my membranes. The filter stops anything bigger than 5 microns but anything smaller is still going through
Brown? Mine went a much darker shade of grey than usual.
A few years ago the water was making the sediment filter brown. Apparently, there was a lot more iron in the water than there should have been. So I put an extra iron pre-filter on the front end. After doing that, the sediment pre-filters looked clean when changed. The iron pre-filter was much larger and much more expensive but I only changed it once a year.
However, this may well not be your problem because this only occurred after a lot of persistent rainfall and some flooding - which presumably put more iron into the supply.
If there is a way of getting the mains water analyzed, it may be worthwhile putting another pre-filter on the front end. Not necessarily iron though. I was told at the time that there are a range of pre-filters available for various chemical filtering. They may have to be specially ordered as it's not the sort of thing that most WFP suppliers would stock.
Just a quick question. Has the location of your RO changed in recent months?