In this guide 6 sections
Build a table that links each purifier and filter model to the cartridges that fit it, with stage and rated life. Record the install date from the order. Work out the due date from the shorter of the litre or month rating, then send a reminder whose button opens the right cartridge in a basket.
Start with a fitment table for every model you sell
One table drives the whole finder. Each row pairs a purifier or filter model with a cartridge, using the model number printed on the rating plate or the back label, not the marketing name.
Take the data from service manuals and parts diagrams, and mark which cartridges are original, which are compatible makes and which a newer part number has replaced. Memory is not a source.
Cover every type you sell, from reverse osmosis units and under-sink systems to jug filters and refrigerator filters, because each has its own set of stages. A jug takes one cartridge. An RO unit can take five.
- Model number and brand, exactly as printed on the unit
- Type: reverse osmosis, ultraviolet, under-sink, countertop, jug or refrigerator
- Stage: sediment, carbon block, membrane, UV lamp or post-carbon
- Cartridge part number, with any superseding part number
- Quantity needed per service and whether a kit exists
Write the cartridge life as a rule the system can run
Makers rate a cartridge in litres, months or both, whichever runs out first, so store both numbers per stage and use the earlier due date. Rated life differs by brand and by stage, so copy the figures from the maker’s manual and store the page reference beside each one.
You cannot read litres from outside a kitchen. Estimate them from household size and typical daily draw, then treat the month rating as the practical limit and shorten it for heavy use.
Stages age at different speeds. A sediment pre-filter clogs sooner than a carbon block, and a membrane usually outlasts both, so give each stage its own date and its own reminder. Muddy or hard supply water shortens every figure, so ask the water source at checkout, municipal or well, and pull the date forward when the answer is well.
Capture the install date from the order
The order date is not the install date. Take the carrier’s delivery scan as the earliest date, then replace it with the job card date where your own technician fitted the unit.
For units bought elsewhere, ask. A short form on the finder page takes the model number and the month of the last change, which starts the clock for a customer you have never billed.
Each cartridge order resets one stage only. Record the delivery date against that stage, so a new carbon block never restarts the clock on the sediment filter or the membrane.
- Delivery scan date from the carrier
- Technician job card date, where you install
- The customer’s own date, from a reply or the finder form
- The stage and part number that the date applies to
Send the reminder with a basket that is already filled
Send the reminder shortly before the due date, by the channel the customer agreed to, whether email, SMS or WhatsApp. Name the model and the part.
The button should open a basket holding that cartridge, or the full kit when two stages fall due together, with the model name above it. Add a link reading not your unit. A wrong match is then easy to fix.
If nothing happens, send one follow-up. Stop the moment the customer buys. Offer a snooze for a few weeks, and offer a subscription to anyone who has reordered the same cartridge more than once.
- Model name, so the customer sees the match is right
- The stage due and the reason, in one plain sentence
- Cartridge or kit with its part number already in the basket
- A link to change the model if the match is wrong
- Snooze and unsubscribe links
Test it on real units and count the misfits
Pick ten models and search for each the way a customer would, by model number, by brand and by a misspelt name. Try missing hyphens and stray spaces. Check stages and part numbers.
Add a return tag for a wrong-match cartridge. Each tagged return points to a row that is wrong or missing, and each should be fixed within the week.
Give the finder a route for models it cannot find, with a photo of the rating label, and read those submissions every Friday. Add any model that appears twice.
Cartridge fitment and reminder sheet
A two-block sheet. The first block is the fitment table, with columns for brand, model number, unit type, stage, cartridge part number, superseding part number and kit option. The second block is the reminder rule, with rated litres, rated months, install date source, due date, message channel and basket link. One row per model and stage.
Open a blank worksheet to printQuestions owners ask
How do I find which cartridge fits a purifier?
Start from the model number on the rating plate or the back label, not the brand name, then match it to the maker’s parts list. Record each stage and part number.
Can the finder cover units I did not sell?
Yes. Ask for the model number and the month the cartridge was last changed, and set the clock from that answer. Call the date an estimate in the message. A customer who changed the cartridge last month will reply with the real date, which is better data than any guess.
Should reminders count months or litres?
Use both, and act on whichever limit arrives first. Litres cannot be read from outside the unit, so the month rating usually sets the date, shortened for heavy use or hard water.
Which channel suits a replacement reminder?
The one the customer opted into. That may be email, SMS or WhatsApp, and each message should be short, carry one button and be backed by a record of when consent was given.