A method of manufacturing colored bulked continuous carpet filament from a polymer melt comprising polyethylene terephthalate using liquid colorant, the method comprising: - providing a static mixing assembly comprising at least twenty static mixers arranged in series; - providing a liquid metering system; - providing a first liquid colorant having a first color; using the liquid metering system to inject the first liquid colorant into the polymer melt; after the step of using the liquid metering system to inject the first liquid colorant into the polymer melt, passing the polymer melt and the first liquid colorant through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant; and after the step of passing the polymer melt through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant, forming the polymer melt into bulked continuous carpet filament having a color based on the first color, characterized in that the method comprises the steps of: - providing a second liquid colorant having a second color; - using the liquid metering system to cease injection of the first liquid colorant into the polymer melt; - after the step of using the liquid metering system to cease injection of the first liquid colorant into the polymer melt, using the liquid metering system to inject the second liquid colorant into the polymer melt; - forming the polymer melt into bulked continuous carpet filament having a waste color for at least a color changeover time; - after the color changeover time has passed, passing the polymer melt and the second liquid colorant through the static mixing assembly to substantially thoroughly mix the polymer melt with the second liquid colorant; - after the step of passing the polymer melt through the static mixing assembly to substantially thoroughly mix the polymer melt with the second liquid colorant, forming the polymer melt into bulked continuous carpet filament having a color based on the second color. - providing a static mixing assembly comprising at least twenty static mixers arranged in series; - providing a liquid metering system; - providing a first liquid colorant having a first color; using the liquid metering system to inject the first liquid colorant into the polymer melt; after the step of using the liquid metering system to inject the first liquid colorant into the polymer melt, passing the polymer melt and the first liquid colorant through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant; and after the step of passing the polymer melt through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant, forming the polymer melt into bulked continuous carpet filament having a color based on the first color, characterized in that the method comprises the steps of: using the liquid metering system to inject the first liquid colorant into the polymer melt; after the step of using the liquid metering system to inject the first liquid colorant into the polymer melt, passing the polymer melt and the first liquid colorant through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant; and after the step of passing the polymer melt through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant, forming the polymer melt into bulked continuous carpet filament having a color based on the first color, - providing a second liquid colorant having a second color; - using the liquid metering system to cease injection of the first liquid colorant into the polymer melt; - after the step of using the liquid metering system to cease injection of the first liquid colorant into the polymer melt, using the liquid metering system to inject the second liquid colorant into the polymer melt; - forming the polymer melt into bulked continuous carpet filament having a waste color for at least a color changeover time; - after the color changeover time has passed, passing the polymer melt and the second liquid colorant through the static mixing assembly to substantially thoroughly mix the polymer melt with the second liquid colorant; - after the step of passing the polymer melt through the static mixing assembly to substantially thoroughly mix the polymer melt with the second liquid colorant, forming the polymer melt into bulked continuous carpet filament having a color based on the second color.