esphome-magnetometer-water-gas-meter

This ESPHome package allows reading your water meter or gas meter using the QMC5883L or HMC5883L, a triple-axis magnetometer.

TLDR; Add this to your ESPHome device configuration:

substitutions:
  volume_unit: 'gal'
  i2c_scl: GPIO5  # D1
  i2c_sda: GPIO4  # D2
  # Set to false only if needed during manual calibration.
  # Do not keep them at false since these slow down the ESP device
  # and reduce the accuracy during high flow.
  hide_magnetic_field_strength_sensors: 'true'
  hide_half_rotations_total_sensor: 'true'

packages:
  meter:
    url: https://github.com/tronikos/esphome-magnetometer-water-gas-meter
    ref: main
    file: esphome-water-meter.yaml
    # Or for gas meter:
    # file: esphome-gas-meter.yaml
    # Or if you are using HMC5883L instead of QMC5883L:
    # files: [esphome-water-meter.yaml, hmc5883l.yaml]
    refresh: 0s

Compatibility

Water meter

The magnetometer is used to read the rotating magnet inside your water meter.

This should be compatible will all the water meters the Flume water sensor is compatible with, which is compatible with about 95% of water meters in the United States.

To verify compatibility follow this. Alternatively, install the Sensors app on your phone, place your phone next to the meter, and see if the Geomagnetic Field sensors are changing while water is running.

Video showing the internals of a water meter.

See Figure 1: Nutating disc operation

"The metering principle, known as positive displacement, is based on the continuous filling and discharging of the measuring chamber. Controlled clearances between the disc and the chamber provide precise measurement of each volume cycle. As the disc nutates, the center spindle rotates a magnet. The movement of the magnet is sensed through the meter wall by a follower magnet or by various sensors. Each revolution of the magnet is equivalent to a fixed volume of fluid, which is converted to any engineering unit of measure for totalization, indication or process control."

Magnetometer position for water meter

Gas meter

The magnetometer is used to read the diaphragm that expands and contracts inside your gas meter.

This should be compatible with all diaphragm/bellows meters which are the most common type of gas meter, seen in almost all residential and small commercial installations.

To verify compatibility install the Sensors app on your phone, place your phone next to the meter, and see if the Geomagnetic Field sensors are changing while gas is running.

Video showing the internals of a gas meter.

Magnetometer position for gas meter

Hardware installation

Parts

ESP8266 or ESP32 with power adapter
- I placed mine inside the garage
- For high flow meters a dual core ESP32 is strongly preferred
QMC5883L or HMC5883L magnetometer
- I placed mine in the water meter box 20ft away from the garage
Ethernet cable
- I used 32.8ft or 10m direct burial CAT6. A user has reported they successfully used 75ft or 22.9m direct burial CAT6.
- CAT6 is preferred because of its lower capacitance. CAT5 50ft or 15m should work. For 100ft you will need an active terminator such as LTC4311.
- Do not use thermostat wire, bell wire, or any other low voltage wire. You will have communication errors or instability. You really need to be using twisted pair cables with proper shielding and lower capacitance such as CAT6.
Some way to weather proof the magnetometer. Some options:
- Adhesive 4:1 heat shrink tubing (this is what I used)
- Liquid electrical tape
- Silicone sealant
- Nail polish
- Hot glue
Some way to mount the magnetometer on the meter. Some options:
- Cable zip tie (this is what I used)
- Duct tape
Conduit for the ethernet cable. Can be skipped if using direct burial ethernet cable.

Wiring

QMC5883L	ESP8266
VCC	5V
GND	GND
SCL	D1
SDA	D2

The ethernet cable has 4 twisted pairs of wires. Use any solid wire color for the 4 above pins. Tie the 4 white wires together with the GND solid wire. You might need to use a header pin for the GND. If you use a header pin cut the 5 GND wires shorter to avoid the ball of wires I had...

magnetometer wiring magnetometer in adhesive heat shrink tubing d1 mini wiring d1 mini lego case driveway

Software installation

Setup ESPHome, if you don't have it already, by following Getting Started with ESPHome and Home Assistant.
In the ESPHome Dashboard select New device, Continue, give a name: e.g. Water meter, Next, select device type based on the ESP chip used e.g. ESP8266.
In the Configuration created! page select Skip to skip installation for now until we make a few changes.
Select Edit on the created configuration e.g. water-meter.yaml.

Skip this step if you used an esp32. Change esp8266 section to:

esp8266:
  board: d1_mini
  restore_from_flash: true

preferences:
  flash_write_interval: 60min

Add the following (either at the beginning or the end of the file):

substitutions:
  # For water one of: CCF, ft³, gal, L, m³
  # For gas one of: CCF, ft³, m³
  volume_unit: 'gal'
  i2c_scl: GPIO5  # D1
  i2c_sda: GPIO4  # D2
  # Set to false only if needed during manual calibration.
  # Do not keep them at false since these slow down the ESP device
  # and reduce the accuracy during high flow.
  hide_magnetic_field_strength_sensors: 'true'
  hide_half_rotations_total_sensor: 'true'

packages:
  meter:
    url: https://github.com/tronikos/esphome-magnetometer-water-gas-meter
    ref: main
    file: esphome-water-meter.yaml
    # Or for gas meter:
    # file: esphome-gas-meter.yaml
    # Or if you are using HMC5883L instead of QMC5883L:
    # files: [esphome-water-meter.yaml, hmc5883l.yaml]
    refresh: 0s

Change the values in the substitutions section based on your setting, e.g. if you have used different pins, or if you prefer a different unit.

Your configuration should now look something like the following:

substitutions:
  volume_unit: 'gal'
  i2c_scl: GPIO5  # D1
  i2c_sda: GPIO4  # D2
  # Set to false only if needed during manual calibration.
  # Do not keep them at false since these slow down the ESP device
  # and reduce the accuracy during high flow.
  hide_magnetic_field_strength_sensors: 'true'
  hide_half_rotations_total_sensor: 'true'

packages:
  meter:
    url: https://github.com/tronikos/esphome-magnetometer-water-gas-meter
    ref: main
    file: esphome-water-meter.yaml
    # Or for gas meter:
    # file: esphome-gas-meter.yaml
    refresh: 0s

esphome:
  name: water-meter
  friendly_name: Water meter

esp8266:
  board: d1_mini
  restore_from_flash: true

preferences:
  flash_write_interval: 60min

# Enable logging
logger:

# Enable Home Assistant API
api:
  encryption:
    key: "L8408egzTATPCBT1nzvFpqj4YlVERRO31+GyB/yjf4E="

ota:
  - platform: esphome
    password: "d44ed9df293facf65e288062d5c7a5e7"

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "water-meter Fallback Hotspot"
    password: "8cSGOshkb2Rw"

captive_portal:

Select Save and then Install.
Only for the first install select Plug into this computer. For subsequent updates/installs you can install Wirelessly.
Select Download project to save a bin file.
Select Open ESPHome Web, Connect, Install downloaded project.
In the Install your existing ESPHome project page select Choose File, select the previously downloaded bin file, and select Install.
Home Assistant should auto-discover your new device.

Calibration

Magnetic field axis and thresholds

To calibrate these just run a light stream of water/gas and press the "Calibrate axis" button. After 5 seconds (configurable) the proper axis and thresholds should be set.

Alternatively:

Temporarily set hide_magnetic_field_strength_sensors: 'false' to show the Magnetic Field Strength X, Y, and Z sensors in HA.
Run a light stream of water/gas.
Observe which axis changes the most and its range.

Set the axis and thresholds. e.g. if y axis ranges from min to max use:

Axis = y
Threshold lower = min + 0.25 * (max - min)
Threshold upper = max - 0.25 * (max - min)

Set hide_magnetic_field_strength_sensors: 'true'.

Volume per half rotation

This depends on your specific water/gas meter model and its size.

You can search for specifications of your specific water/gas meter and its size. e.g. for Neptune T-10:

Meter size	Pulses/Gallon
5/8"	231.24
3/4"	129.04
1"	60.32
1 1/2"	27.03
2"	14.92

So for a 5/8" Neptune T-10 you will set this to 0.00864902 (2 / 231.24)

If you have the Flume water sensor you can use its lowest reported value. You can find it with: select min(min) from statistics_short_term, statistics_meta where statistics_meta.statistic_id = 'sensor.water_usage_current' and statistics_meta.id = metadata_id and min > 0;

Alternatively:

Temporarily set hide_half_rotations_total_sensor: 'false' to show the "Half rotations total" sensor in HA.
Write it down and also write down the reading on your water/gas meter.
After a few hours or even days of regular water/gas usage, write down both of them again.
Set this to the result of: diff of readings in volume_unit divided by diff of half rotations.
Set hide_half_rotations_total_sensor: 'true'.

For water meters this defaults to 0.01008156 gal which is for my 3/4" Badge Meter Model 35. For gas meters this defaults to 0.125 ft³ which seems to be the most common in US. If you have modified the volume_unit you have to manually convert this value. E.g. if for gas you used volume_unit: 'CCF' then you need to set the volume per half rotation to: 0.00125 CCF (just search on Google 0.125 ft³ to CCF).

Temperature

Only supported if you are using a QMC5883L. Place another temperature sensor next to the QMC5883L and adjust the temperature offset so that they match.

Home Assistant alerts

I'm using the Alert integration to get alerted if there is a leak.

In /homeassistant/configuration.yaml I have:

alert: !include alerts.yaml

template:
  - sensor:
    - name: Water running for 45 minutes
      unique_id: water_running_45min
      device_class: "moisture"
      icon: mdi:waves
      delay_on:
        minutes: 45
      # Subtract irrigation system that consumes 0.28 gal/min between 7 to 9 am or 8 to 10 am depending on DST
      state: "{{ max(0, states('sensor.water_meter_flow') | float - (0.3 if now().hour in range(7, 10) else 0)) > 0 }}"
    - name: Water running for 20 minutes at more than 1.5 gal/min
      unique_id: water_running_20min
      device_class: "moisture"
      icon: mdi:waves
      delay_on:
        minutes: 20
      state: "{{ max(0, states('sensor.water_meter_flow') | float - (0.3 if now().hour in range(7, 10) else 0)) > 1.5 }}"

notify:
  - platform: group
    name: nikos
    services:
      - service: persistent_notification
      - service: mobile_app_pixel_7a
      - service: mobile_app_le2125
  - platform: group
    name: nikos_mobile
    services:
      - service: mobile_app_pixel_7a
      - service: mobile_app_le2125
  - platform: group
    name: wife
    services:
      - service: mobile_app_wife_iphone
  - platform: group
    name: all
    services:
      - service: nikos
      - service: wife
      - service: google_assistant_sdk
      - service: alexa_media_garage_ecobee_switch

In Settings > Devices & services > Helpers I have created a group binary_sensor.water_leak_sensors_group with the above 2 sensors together with all my water leak sensors.

In Settings > Automations I have created the following automation to get notified if I ever forget to add a new sensor to the group:

alias: "Notify: incomplete groups"
description: ""
trigger:
  - platform: time
    at: "10:01:00"
action:
  - if:
      - condition: template
        value_template: "{{ missing_moisture_sensors != '' }}"
    then:
      - service: notify.nikos
        data:
          message: |-
            binary_sensor.water_leak_sensors_group is missing:
            {{missing_moisture_sensors}}
variables:
  missing_moisture_sensors: |
    {{ states.binary_sensor
        | rejectattr('attributes.device_class', 'undefined')
        | selectattr('attributes.device_class', '==', 'moisture')
        | rejectattr('attributes.entity_id', 'defined')
        | map(attribute='entity_id')
        | reject('in', states.binary_sensor.water_leak_sensors_group.attributes.entity_id)
        | join('\n') }}
mode: single

In /homeassistant/alerts.yaml I have the following to keep alerting me every 5 minutes in case of a leak:

water_leak:
  name: Water leak detected
  message: "Water leak detected at {{ expand('binary_sensor.water_leak_sensors_group') | selectattr('state', '==', 'on') | map(attribute='attributes.friendly_name') | join(', ') | lower() | replace(': water leak sensor', '') | replace(' leak sensor moisture', '') }} {{ relative_time(states.binary_sensor.water_leak_sensors_group.last_changed) }} ago"
  done_message: Water leak not detected anymore
  entity_id: binary_sensor.water_leak_sensors_group
  state: "on"
  repeat: 5
  can_acknowledge: true
  skip_first: false
  notifiers:
    - all
  data:
    push:
      sound:
        name: "default"
        critical: 1
        volume: 1.0
    ttl: 0
    priority: high
    media_stream: alarm_stream_max
water_leak_tts:
  name: Water leak detected (TTS)
  message: TTS
  done_message: Water leak not detected anymore
  entity_id: binary_sensor.water_leak_sensors_group
  state: "on"
  repeat: 5
  can_acknowledge: true
  skip_first: false
  notifiers:
    - nikos_mobile
  data:
    ttl: 0
    priority: high
    media_stream: alarm_stream_max
    tts_text: "Water leak detected"

In my main dashboard I have the following auto-entities card, which is typically hidden when empty:

type: custom:auto-entities
show_empty: false
card:
  title: Active Alerts
  type: entities
  state_color: true
filter:
  include:
    - domain: alert
      not:
        state: idle
    - domain: binary_sensor
      attributes:
        device_class: moisture
      not:
        state: 'off'

In Settings > Devices & services > Helpers I have created a Utility Meter sensor.water_meter_daily_total to keep track of my daily water usage.

In Settings > Automations I have created the following automation to get notified if my daily water usage is abnormal:

alias: "Notify: water usage"
description: ""
trigger:
  - platform: time
    at: "23:59:00"
condition: []
action:
  - if:
      - condition: numeric_state
        entity_id: sensor.water_meter_daily_total
        above: 100
    then:
      - service: notify.nikos
        metadata: {}
        data:
          title: High daily water usage
          message: >-
            Consumed {{ states('sensor.water_meter_daily_total') }} gal today.
            Is there a leak?
  - if:
      - condition: numeric_state
        entity_id: sensor.water_meter_daily_total
        below: 10
    then:
      - service: notify.nikos
        metadata: {}
        data:
          title: Low daily water usage
          message: >-
            Consumed {{ states('sensor.water_meter_daily_total') }} gal today.
            Do you need to reposition or recalibrate the sensor?
mode: single

tronikos / esphome-magnetometer-water-gas-meter

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