Plastic bottles are more environmentally friendly.

Glass requires massively more energy to manufacture, even using 100% recycled glass. Glass is heavy, so it's more expensive to transport. Collecting and washing bottles for re-use consumes a substantial amount of energy, which greatly increases the number of trips required to break even on the higher manufacturing impacts. The lifespan of a re-usable glass bottle is relatively very short, because glass is fragile. Glass compares poorly to HDPE when we factor in a realistic lifespan for glass and a realistic recycling rate for HDPE.