SensingDesign complete (stages 1–6), not built

PureTrack

Litre and pump-hour meter that tells RO dealers whose filters are due

Counts litres dispensed and pump run hours on an existing RO purifier and gives the RO service dealer a weekly list of customers whose filters or membrane are due, with a chart the customer can see.

Who buys it: Independent RO sales-and-service dealers and AMC companies in India (300 to 5,000 customers each); the household uses it and pays nothing extra.
Why it pays: On a 1,500-customer book, about $2,100 a year of wasted calendar visits avoided and about $700 a year of filter and membrane margin kept from roadside mechanics (est.).
Target price: ₹1,499 ($18) per meter, ₹1,999 with output-TDS probe, ₹299 per meter per year after year 1 (target)
First-minute wow: The dealer opens a due list grouped by pin code, and each customer page shows a 90-day chart of litres and pump seconds per litre that explains why the membrane needs changing.

See the CAD design Concept page

PureTrack concept: the idea and where each part goes — The concept. The CAD design is below, under Printable CAD.

What the research found

And how this design answers it

$5 TDS pens and IS 16240's mandatory TDS display → input TDS dropped; measures litres, pump run time and pump current, which pens can't
Consumers won't pay → the dealer buys it and earns from due-list dispatch and filter sales
Homes without Wi-Fi → BLE-first with a year of on-device records, synced by the technician app; Wi-Fi optional
Hall sensors can't read 0.2 L/min permeate → sensor on the dispense line; membrane health inferred from pump seconds per litre
Food contact → no printed part touches water; only bought, certified wetted parts
Bypass and fake resets → flow and pump cross-check, logged resets, never locks out other servicers

Use case

Due-list dispatch instead of calendar visits

Dealer ownerTechnicianCustomer

01Trigger: Monday morning the dealer opens the due list
02Detection: each meter's stage counters are forecast 14 days ahead from the last sync
03Alert: 41 customers due this week, grouped by pin code, with sync confidence
04Action: technicians visit only those customers, sync and record a signed service reset

Outcome: About 900 wasted visits a year avoided on a 1,500-customer book, roughly $2,100 (est.)

How it works

Architecture

01
Sense: hall flow sensor on the tap line, INA226 on the pump's 24 V feed, optional output-TDS tee
02
Decide: ESP32-C3 keeps stage counters and a year of hourly records; LEDs work offline
03
Send: BLE sync through the technician or customer app; MQTT over TLS when Wi-Fi is available
04
Tell: cloud rules build the dealer's due list, membrane and pump alerts, and WhatsApp reminders from the dealer's own number

Hardware

Real parts, buyable today

Bill of materials: about $24 per meter with the TDS probe at qty 10–100 (est.).

Block	Part	Why this part
MCU + radio	Espressif ESP32-C3-MINI-1-N4	BLE + Wi-Fi with secure boot for about $3
Pump sensing	TI INA226 + 50 mΩ shunt	36 V bus; pump on/off, run time and current from the purifier's own 24 V line
Flow	1/4 inch quick-connect hall flow sensor, 0.3–10 L/min	Counts litres at the tap, calibrated with a 1 L jug at install
Power	TI TPS560430 buck	Runs from 4–36 V; no extra adapter
Time	NXP PCF85063A RTC + 0.22 F supercap	Keeps timestamps through wall-switch power cuts

Mechanical

Printable CAD

6 parts, generated from code and checked as closed solids. Pick a part to inspect it, or download the STL files to print.

See the CAD parts render

PureTrack printable parts, rendered from the CAD — Render of the printable parts from the actual CAD. Not yet printed or photographed.

Loading the CAD…

Real CAD · drag to rotate · scroll to zoomReal CAD · swipe sideways

Open risks we are working on

Dealers may not pay ₹1,499 upfront; fallback is a ₹49/month rental bundled into the AMC
No potable-certified 1/4 inch hall flow sensor confirmed yet; blocks sales, not the bench build
Big purifier brands may add cheap connectivity to every new model within a few years
Without Wi-Fi, data is only as fresh as the last technician or customer sync

Design stage only: nothing on this page is for sale. Specifications and prices are targets.