Can I just replace all filters once a year?
You'd be throwing away a healthy membrane yearly and possibly running dead carbon for months. Stagger by stage — it's cheaper and the water is better.
Forget the calendar. Learn the signals.
Manufacturer schedules are written to sell filters. Here's what each stage actually does and how to tell when it's spent:
| Stage | What it does | Typical life | Replace signal |
|---|---|---|---|
| PP spun sediment (5 micron) | Catches sand, rust, silt — protects everything downstream | 3–6 months | Visible browning; pressure drop at faucet |
| CTO carbon block | Removes chlorine, taste, odor — protects the RO membrane from chlorine damage | 6–12 months | Chlorine taste returns; filtered TDS starts climbing |
| RO membrane (0.0001 micron) | Removes dissolved salts, heavy metals, most contaminants | 2–3 years | Rejection rate drops after pre-filter change |
| T33 post-carbon | Polishes taste of stored/tankless product water | ~12 months | Flat or stale taste |
Stages protect each other in sequence. A spent $8 sediment filter lets grit scar the carbon block; a spent carbon block lets chlorine eat the $40 membrane. Skipping cheap pre-filter changes is how you kill expensive membranes early. The schedule above is the cheap insurance version.
When in doubt, don't guess — test. A rising filtered-water TDS tells you something is spent; changing pre-filters first and retesting tells you whether the membrane survived. Numbers beat schedules.
Low-TDS municipal water extends membrane life but doesn't extend carbon life much — chlorine is dosed regardless of TDS, and carbon's job is eating chlorine. Don't stretch carbon changes just because your TDS looks good.
You'd be throwing away a healthy membrane yearly and possibly running dead carbon for months. Stagger by stage — it's cheaper and the water is better.
Chlorine reaches the RO membrane and destroys it (TFC membranes are chlorine-intolerant), and sediment blinds the carbon block. A $15 skipped change becomes a $40+ membrane replacement.
No — housings last years. Rinse them during filter changes. Replace O-rings if you see weeping at the seam; a $2 O-ring beats a new housing.
No. Every filter is a consumable by physics: sediment fills up, carbon exhausts, membranes foul. Anyone selling 'lifetime' filters is selling a subscription to disappointment.
One spare set of pre-filters, yes — so a brown sediment filter never waits for shipping. Membranes can be ordered when TDS tells you to.