The schedule
- Under-Sink RO · sediment
- Sediment Pre-Filter · every 6 months
- Under-Sink RO · pre-filters
- Carbon Cartridge Pair · every 6 months
- Under-Sink RO · membrane
- RO Membrane · every 2–3 years
- Under-Sink Carbon
- Carbon Cartridge Pair · every 6 months
- Countertop
- Countertop Cartridge · every 6 months
- Faucet Mount
- Faucet Cartridge · every 3 months
- Shower Filter
- Shower Cartridge · every 6 months
How you will know
Three signals, in the order you usually notice them. Flow slows — a gravity system that took four hours starts taking six. Taste returns — chlorine is the first thing carbon stops removing when it is exhausted. The date passes — write it on the housing in pencil when you fit it, which is more reliable than either of the above.
Doing it yourself
Shut the supply, open the tap to drop the pressure, and unscrew the housing with the wrench that came with the system. Lift the old cartridge out, drop the new one in, hand-tighten, and run two full cycles to waste before you drink. That last step matters — the first water through a new carbon cartridge carries harmless carbon fines and looks grey.
None of these need a plumber. The under-sink systems are the only ones that touch a supply line at all, and that is a shut-off valve and a push-fit connector.
Reminders, not subscriptions
If you tell us what you fitted and when, we will email you when the cartridge is due. That is the entire programme. There is no recurring charge, no card kept on file for it, and nothing to cancel — if you would rather buy it yourself when the flow slows, that works just as well.