Quick take
At current one-time list prices, the three core G3P600 cartridges annualize to about $145 per year: roughly $60 for CF, $30 for CB and $55 for the RO membrane.
CF cost per year
G3-N1CF is $29.99 and is rated up to six months, producing about $59.98 per year on the nominal schedule.
CB cost per year
G3-N3CB is $29.99 and rated up to 12 months, or about $29.99 per year.
RO membrane cost per year
G3P600-RO is $109.99 and rated up to 24 months, equivalent to about $55 per year when annualized.
What can change the real number
Source-water quality, household volume, subscription discounts, promotions and optional MNR35 or ALK35 cartridges can move real ownership cost above or below the nominal figure.