the water from my apec system tastes weird or has a bad odor after i changed the filters

Diagnosis

The strange taste or "chemical" odor following a filter change on the APEC ROES-50 is typically caused by "carbon fines." The pre-filters and the post-carbon polishing filter contain activated carbon in granular or block form. During shipping and installation, tiny particles of carbon dust break off. If these particles enter the membrane or the storage tank, they can impart a metallic or bitter taste to the water. Additionally, new filter cartridges introduce air pockets into the system. As water pushes through these pockets, it can create micro-bubbles that alter the surface tension and taste of the water, or trap organic compounds that were sitting in the lines. If you smell a "sulfur" or "plastic" scent, it is often the result of the new filter materials reacting with stagnant water in the lines or the RO membrane being momentarily exposed to air during the swap. You can confirm this by taking a sample of water directly from the RO membrane output (before it hits the tank); if that tastes fine but the faucet water tastes bad, the issue is localized in the storage tank or the final polishing stage.

How to Fix It

To eliminate these contaminants, you must perform a full system purge. Do not simply run a few glasses of water; you must bypass the storage tank to ensure the new filters are fully saturated and flushed.

1. Close the blue valve on top of the pressurized storage tank by turning it 90 degrees to the "off" position.
2. Open the RO faucet on your countertop and let the water flow. Because the tank is closed, the flow will be a very slow trickle. This is normal.
3. Allow this trickle to run for 15 to 20 minutes. This forces water through the new sediment and carbon pre-filters, flushing the carbon fines directly into the drain line rather than into your drinking water.
4. Close the RO faucet.
5. Open the storage tank valve slowly to allow the system to refill.
6. Wait for the tank to fill completely (usually 2-4 hours depending on your water pressure).
7. Once full, open the RO faucet and drain the entire tank completely. You will notice the flow is fast at first and then slows down.
8. Repeat the tank drain process one more time. This ensures that any carbon dust that migrated into the tank during the initial refill is completely purged.

If That Didn't Work

• Check the Post-Carbon Filter Installation: Ensure the final stage polishing filter (the horizontal one before the faucet) is seated perfectly. If the O-rings are pinched or skewed, air can leak into the line, causing a "stale" taste. Remove the filter, lubricate the O-rings with a tiny drop of food-grade silicone grease, and re-insert it firmly.
• Sanitize the Storage Tank: If the odor persists, the storage tank may have developed a biofilm or trapped air during the downtime of the filter change. Add a teaspoon of unscented household bleach to the tank via the top port (if accessible) or simply drain and refill the tank three consecutive times to "scrub" the interior bladder.
• Verify Membrane Seal: If the taste is salty or brackish, the RO membrane may have been damaged or shifted during the filter change. Check the membrane housing for leaks. If the TDS (Total Dissolved Solids) reading is significantly higher than usual, the membrane may need replacement.
• Inspect for "Cross-Contamination": Ensure that the tubing from the pre-filters is not touching any non-food-grade surfaces or that no lubricant was used on the filter housings that could have leaked into the water stream.

Heads Up

• Always replace the sediment filter (Stage 1) every 6 months to prevent debris from clogging the carbon blocks, which can lead to "channeling" and poor taste.
• When installing new filters, always ensure the housings are tightened by hand first, then give them a quarter-turn with the wrench. Over-tightening can crack the plastic housings or deform the seals.
• If you have high chlorine levels in your municipal water, the carbon filters will saturate faster. If the taste returns prematurely, consider adding a second carbon pre-filter.
• Never use petroleum-based lubricants on the O-rings of the ROES-50 system, as these will leach chemicals into your drinking water and cause a permanent chemical taste.