There's always black grit in my water

Essential
Essential Forum Participant Posts: 51
edited November 2012 in Caravans #1

I don't use the onboard water tank, preferring to use water direct from the aquaroll.  I sterilise and flush the pipes and taps through at least twice a year and do the same with the barrels but I still get little black specks in the bottom of the washing
up bowl.  Is there something I am missing?