WHY WE LOVE IT: The downside to any water filter, whether at your showerhead or kitchen faucet, is that it can take away water pressure—not ideal when you have a head full of shampoo suds. To be clear, the Weddell will not improve your showerhead's water pressure, but it won't make it worse, which could happen if you choose a filter with a lower flow rate than that of your showerhead. The Duo's long, cylindrical design is among the more conspicuous, and the plastic housing means no matching the filter to your showerhead and other fixtures in the bathroom.