Product review (2 stars): The EcoAqua EFF-6025A fits perfectly, for $11.
EcoAqua filter is virtually identical for a fraction of the price.
Given how much Miele charges, I figured I had nothing to lose trying an $11 replacement.  the EcoAqua EFF-6025A says on its packaging that it is compatible with Bosch UltraClarity, but doesn't mention Miele.  I bought both the Miele and the EcoAqua, just in case the EcoAqua didn't fit.  It fit exactly the same as the Miele, and now that is all I buy.  I have no idea why there are so many reviews suggesting that it doesn't fit - it fits exactly the same as the original - spend $11 and try it for yourself.  Nobody in the house has noticed a difference in taste, which isn't surprising - the filter material is the same.