Diagnosis
The dark brown water is almost certainly caused by loose carbon dust (or "fines") from the brand new filter cartridge. This is a common occurrence with new carbon block filters like the UC-200. The initial flush during manufacturing doesn't remove 100% of this fine particulate, so it flows out when you first use it. It is not harmful, but it is not meant for consumption.
How to Fix It
You need to thoroughly flush the system.
- Ensure the filter's bypass valve is in the "Filter" position (handle aligned with the filter body).
- Open your cold water faucet completely. Let the water run for a full 5-10 minutes into a bucket or down the drain. This purges the carbon dust from the cartridge and housing.
- After flushing, the water should be completely clear. Discard the initial dark water; do not drink it.
If That Didn't Work
If the water remains dark brown after a 10-minute flush, check your installation.
- Flow Direction: Verify the filter is installed in the correct direction. The existing cold water supply line must connect to the INLET port on the bottom cap. The included braided hose from the shutoff valve connects to the OUTLET port on the top cap. Reversing this can cause excessive carbon shedding.
- Cloudy vs. Brown: If the water is milky or cloudy, that's likely just trapped air bubbles from the new installation. Fill a glass and let it sit for a minute; the cloudiness should disappear from the bottom up as bubbles rise.
- If incorrectly installed, turn off the water supply, correct the connections, and perform the flush procedure again.
Heads Up
Always run water through a new filter for several minutes before first use, as stated on the cartridge label. The first few gallons are for flushing only. If the problem persists for days or the water has black specks, the filter cartridge may be defective and should be replaced.