Under-sink filters do a great job improving your tap water — but if you forget to change the cartridge, you’re not getting the protection you paid for.
So how often should you swap it out? That depends on the type of filter, your water quality, and how much water your household uses. Let’s break it down.
✅ Quick Takeaways
- Most under-sink filters need to be replaced every 6–12 months
- Sediment and carbon filters wear out faster than RO membranes
- Hard water, heavy use, or poor quality water shortens filter life
- Signs you need a new filter include bad taste, low pressure, or cloudiness
- Keeping up with replacements ensures your system works as intended
🧼 How Long Filters Last (And Why It Matters)
Filter life varies depending on the type of cartridge, how much water you use, and what’s in your water supply. But no matter the setup, skipping filter changes leads to poor performance — and worse, it can make water quality worse than unfiltered tap.
| 🧪 Filter Type | 📆 Average Lifespan | 💡 Notes |
|---|---|---|
| Sediment | 3–6 months | Protects other filters by catching dirt and rust |
| Carbon Block | 6–12 months | Removes chlorine, chemicals, and improves taste |
| RO Membrane | 1–3 years | Reduces heavy metals, salts, and dissolved solids |
⏳ Remember: even if your water use is low, filters still degrade over time once exposed to moisture. Always follow manufacturer timelines as a baseline.
Curious about different filter types and what they remove? Here’s a guide to popular water filter media.
🕵️♀️ How to Tell When It’s Time for a New Filter
If your system doesn’t have a built-in reminder light or app, you’ll need to rely on a few signs that your filter is past its prime.
🔄 Common Red Flags:
- Water pressure drops A clogged filter slows the flow — a sudden trickle usually means it’s overdue.
- Water tastes or smells off A return of chlorine taste, mustiness, or bitterness means your filter isn’t doing its job.
- Visible grime or discoloration If your filter housing is clear, look for brown or gray buildup. Sediment filters are especially prone to gunk.
💡 If you’re not sure how to access or check your filter, here’s a step-by-step guide to changing under-sink filters safely and cleanly.
🚿 Why Some Filters Wear Out Faster Than Others
Even with manufacturer timelines, real-world filter life can vary a lot depending on how much water you run through your system and what’s in it.
⬇️ Here’s what can shorten lifespan:
- High water usage — Families or heavy kitchen use = faster wear
- Poor source water — More sediment, chlorine, or metals = more stress on filters
- Hard water — Can clog or coat filters faster, especially in multi-stage systems
And remember — the countdown starts as soon as the filter gets wet, not just based on how often you use it.
🔎 For a deeper dive into how different filter types hold up over time, check out our complete guide to filter lifespan.
💰 What Do Replacement Filters Cost?
Replacing your under-sink cartridges isn’t usually expensive — and you don’t need to buy the name brand to get quality.
| Filter Type | 💵 Cost Range (Per Cartridge) |
|---|---|
| Sediment | $5–$15 |
| Carbon Block | $30–$70 |
| RO Membrane | $75–$150 |
💡 Pro Tips to Save:
- Buy in bulk — You’ll often get 2–3 filters for the price of one
- Use compatible generics — Many systems work with non-OEM filters
- Look for certifications — NSF-certified filters are independently tested for safety and performance
Bonus: Most under-sink filters are easy to swap yourself — no plumber required.
✅ Final Thoughts
Under-sink filters are one of those “set it and forget it” upgrades—until they’re not. If you let the filter go too long, it’s like running your car on old oil: not a great idea.
Whether you’re using a basic carbon cartridge or a reverse osmosis setup with all the bells and whistles, a little maintenance keeps things running smooth and your water tasting great.
🗓️ Toss a reminder on your phone, stash a backup filter under the sink, and you’ll never get caught off guard.
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