Janine is considering buying a water filter and a reusable water bottle rather than buying bottled water. will doing so save her money? how much water does janine drink in a day? she normally drinks 3 bottles a day, each 16.9 ounces. how much does a bottle of water cost? she buys 24-packs of 16.9 ounce bottles for $3.39. how much does a reusable water bottle cost? about $10. how long does a reusable water bottle last? basically forever (or until you lose it). how much does a water filter cost? how much water will they filter? a faucet-mounted filter costs about $28 and includes one filter cartridge. refill filters cost about $33 for a 3-pack. the box says each filter will filter up to 100 gallons (378 liters) a water filter pitcher costs about $22 and includes one filter cartridge. refill filters cost about $20 for a 4-pack. the box says each filter lasts for 40 gallons or 2 months an under-sink filter costs $130 and includes one filter cartridge. refill filters cost about $60 each. the filter lasts for 500 gallons. the cheapest option saves her $ over a year.