my express water ro5dx is making water taste kinda flat and boring, is this normal?

Diagnosis

The "flat" or "boring" taste you are experiencing with your Express Water RO5DX is a result of extreme purity, specifically a phenomenon known as "aggressive water." The 5-stage reverse osmosis process is designed to strip away nearly 98% of all dissolved solids, including contaminants, salts, and essential minerals like calcium, magnesium, and potassium. While this ensures the water is safe and free of chemicals, these minerals are exactly what provide the "crisp" or "sweet" flavor profile found in spring water. When the Total Dissolved Solids (TDS) count drops too low—typically below 20-30 ppm—the water becomes chemically unstable and slightly acidic. This happens because the RO process removes the alkaline minerals that normally buffer the pH level. As a result, the water can taste "empty," metallic, or even slightly sour to some palates. You can confirm this by using a digital TDS meter on your faucet output; if your reading is significantly lower than your source water (e.g., source is 300 ppm and RO is 15 ppm), the system is functioning perfectly, but it has over-purified the water for your personal taste preference.

How to Fix It

To restore the flavor profile and balance the pH of your water, you need to introduce a remineralization stage. Since the RO5DX is a standard 5-stage system, the most effective solution is to add an inline remineralization filter after the storage tank but before the dedicated RO faucet.

1. Purchase an inline Remineralization Filter (typically containing calcite and magnesium). Look for a filter with a 1/4" NPT or Quick-Connect fitting to match the RO5DX tubing.
2. Shut off the cold water supply valve leading to the system and close the valve on top of the pressurized storage tank.
3. Locate the blue or white 1/4" polyethylene tubing that runs from the storage tank to the RO faucet.
4. Use a tubing cutter to make a clean, square cut in this line. Avoid using scissors, as crushed tubing leads to leaks.
5. Insert the remineralization filter into the line, ensuring the "Flow" arrow on the filter housing points toward the faucet.
6. Secure the connections using locking clips to prevent the tubing from slipping under pressure.
7. Open the tank valve and the supply valve. Flush the system by running the faucet for 5-10 minutes to purge air and any initial carbon fines from the new filter.

If That Didn't Work

• Check the Post-Carbon Filter: If the water tastes "flat" but also has a slight chemical or plastic hint, your final stage (the GAC polishing filter) may be exhausted. Replace the Stage 5 carbon filter if it has been more than 6-12 months. A saturated carbon filter fails to remove residual tastes from the storage tank bladder.
• Flush the Storage Tank: If the system sat unused for several days, the water in the tank can become stagnant, leading to a dull taste. Open the RO faucet and let the tank drain completely, then allow it to refill. Repeat this twice to ensure fresh water is cycling through the membranes.
• Verify Membrane Integrity: Use a TDS meter to check if the "flatness" is actually a sign of membrane failure. If the TDS is surprisingly high (over 50 ppm when your source is 300), the membrane may be fouled or torn, allowing some minerals through but not enough to taste "good," while failing to remove odors. Replace the RO membrane element.
• Adjust Source Water Temperature: Extremely cold water suppresses the taste buds. Try dispensing the water and letting it reach room temperature in a glass; if the flavor improves, the "flatness" is a temperature-perception issue rather than a chemical one.

Heads Up

• pH Balance: Pure RO water is slightly acidic. Adding a remineralizer not only improves taste but protects your body's mineral balance and prevents the water from leaching minerals from your cookware.
• TDS Monitoring: Do not panic if your TDS rises slightly after adding a remineralization filter. This is intentional and is what creates the "spring water" taste.
• Filter Sequence: Never place a remineralization filter before the RO membrane; the membrane will simply strip out the minerals you just added, wasting the filter and potentially clogging the membrane.
• Leak Checks: After installing any new inline filters, wipe all joints with a dry paper towel. Even a tiny damp spot indicates a loose fitting that could lead to a flood under your sink.