How often should you replace your fridge water filter?

An old filter stops improving taste and smell, slows the flow and can harbour bacteria.

A carbon filter that is not changed on schedule stops doing its job. The UK Drinking Water Inspectorate warns that an overdue carbon cartridge will cease to be effective and may leach other chemicals or bacteria, and the US Centers for Disease Control and Prevention says germs can live and multiply in water filters that are not maintained and replaced. Flow also slows as the filter clogs.

1. Find the filter. Either inside the fridge compartment in the upper right, in the base grille at the front, or behind the unit on the supply line.
2. Note the model number. It is printed on the filter body. Generic equivalents vary considerably in quality, so check certification rather than price.
3. Twist or push to release. Many are quarter-turn. Some push-in types release with a button. Have a cloth ready for the small spill.
4. Fit the new filter. Align, insert and turn until it seats firmly. Do not force it past the stop.
5. Flush the amount your manual gives. This is more than most people run. GE says about three minutes, roughly one and a half gallons; Whirlpool says many of its refrigerators need 2 to 4 gallons. Discard the water. It purges trapped air and loose carbon.
6. Reset the indicator light. Usually a press and hold on the filter reset button for a few seconds.
7. Discard the first few batches of ice. GE gives this instruction for models without a dispenser, and it is sensible on any model.

• Water flow from the dispenser slowing noticeably
• A chlorine or musty taste returning
• Ice cubes cloudy or smaller than usual
• The filter indicator light on, which is a timer and not a measurement but still a useful prompt

• Not flushing enough water through, which leaves cloudy water and small black specks of carbon in the first glasses
• Buying an uncertified generic filter: the CDC says to look for an NSF certification on the label, where Standard 42 covers taste and odour and Standard 53 covers health-related claims such as cyst reduction
• Leaving a filter in for years because the water still tastes fine
• Assuming it makes unsafe water safe: the CDC says fridge filters are mainly there to improve taste and smell and are not designed to remove germs
• Forgetting the ice maker has been making ice through the old filter the whole time

• Households using the dispenser heavily may need a change sooner than six months, so go by the indicator as well as the date
• Sediment-heavy well water clogs a fridge filter quickly and really needs a whole-house filter upstream
• The date matters even in a lightly used holiday home

If flow is still poor with a new filter, the issue is upstream: the supply valve, a kinked line, or a frozen fill tube. That may need an appliance technician.