my brita longlast filter is making the water taste weird, like dust?

Yeah, that's carbon dust from a new filter. It's normal.

1. Before first use, flush the new filter under cold, running tap water for 15 seconds.
2. Install it in the reservoir, making sure the groove lines up with the ridge.
3. Fill the pitcher completely with cold tap water and let it filter through.
4. Discard the first three full pitchers of filtered water (or use it on plants).

If the taste persists past three pitchers, check that you're using cold tap water only. Hot water above 85°F can damage the filter.

Also, pour water into the reservoir on the side, not directly on top of the filter, to minimize stirring up any residual carbon.