The post-filter (5th stage in-line carbon filter) needs replacement, or the membrane is spent.
- First: Replace the in-line carbon filter (the 5th-stage filter). This is the final "polishing" filter that removes any lingering taste.
- Second: Check your filter change schedule. The sediment (1st stage) and carbon block filters (2nd & 3rd stage) should be changed every 6-12 months. The RO membrane (4th stage) lasts 2-3 years. Old pre-filters can overwhelm the membrane.
- Third: Test the water's TDS (Total Dissolved Solids) level with a meter. A reading higher than normal indicates the membrane is no longer rejecting contaminants effectively and needs replacement.
If that didn't work, the system may be bypassing.
- Ensure all tubing connections are secure, especially at the faucet and the tank ball valve.
- Let the system run for a few minutes to flush any stagnant water from the tank and lines before tasting.
Heads up: The system is certified for feed water TDS up to 2000 ppm. If your tap water is harder than that, it will shorten the membrane's life.