I don’t think it is a pressure issue if it gets worse over time.
Also “corrosion inhibitor is added to help prevent leaching of lead and copper that might be in household plumbing. Fluoride is added to protect teeth. Powdered activated carbon and potassium permanganate may also be added to the treatment process to remove taste and odor- causing compounds.” From your cities report. Maybe that is causing some issue? Not sure what it is or how it would interact in a membrane.
Also “corrosion inhibitor is added to help prevent leaching of lead and copper that might be in household plumbing. Fluoride is added to protect teeth. Powdered activated carbon and potassium permanganate may also be added to the treatment process to remove taste and odor- causing compounds.” From your cities report. Maybe that is causing some issue? Not sure what it is or how it would interact in a membrane.