買熱水器有“Maintenance free - no filter to clean or replace”是不是就

不要每年維護了？有沒有filter有多重要呀？

HD的沒有filter， 但我沒有10%off。
https://www.homedepot.com/p/Rheem-Performance-Platinum-40-Gal-Tall-12-Year-40-000-BTU-Natural-Gas-Tank-Water-Heater-XG40T12HE40U0/204697784

Lowes'的估計有filter， 但我有10% off
https://www.lowes.com/pd/A-O-Smith-Signature-Select-40-Gallon-Short-9-Year-Limited-Natural-Gas-Water-Heater/1000542617