Except I have hardish water from my well and no issues.I wonder if users like myself who simply rinse their brushes with no extra cleaning required are living in soft water areas. Brush maintenance is so very simple that for there to be significant numbers of experienced B&B members who are having to clean their brushes then there must be another factor in play. I wonder if they have a hard water domestic supply with a high mineral content which is causing a build up of residue in the knot. If so then simply advising them to rinse their brush thoroughly or wash it out in the shower is pretty useless advice