Water (pool) temperature monitoring with Home Assistant

· 3 min read
Water (pool) temperature monitoring with Home Assistant


The goal of this blog is to set up a cost effective solution to monitoring your pool water temperature in real time and visualize it in Home Assistant.


To measure the temperature in water we need a waterproof probe of course and I found this one very cheap and very robust  : DS18B20 (Dallas)

and of course a Wemos D1 (ESP)


the wiring is very simple here :

Using ESPHome in Home Assistant

There are several possibilities to generate code to upload it on a ESP(wemos). I chose to use ESPHome in Home Assistant which is simple :

Go to the ESPHome add-on in Home Assistant and create your Secrets if it has not been done yet

Secret Creation

Now it's time to define the secrets in ESPHome by clickinbg on secrets in the upper right corner

Fill with you personnal wifi information :


Now the code to send the this new device needs to be written to be able to measure the temperature of water in the pool

Let's click on the bottom right corner on + New Device :

Give it a name

Chose the device type

Then click on Install (this device doesn't exist anymore, the encryption key is RIP)

As I plugged this ESP on my Home Assistant I chose the following

Chose the correct port to intiate the communication

and when it's done, we can proceed to the upload of the code by clicking on Edit of this new ESP device

You can paste the following code as it is :

  name: pool-temp
  platform: ESP8266
  board: d1_mini

# WiFi connection, replace these with values for your WiFi.
  ssid: !secret wifi_ssid
  password: !secret wifi_password

# Enable logging

# Enable Home Assistant API

# Enable over-the-air updates.

# Enable Web server.
  port: 80
# Sync time with Home Assistant.
  - platform: homeassistant
    id: homeassistant_time

# DS18B20 Temperature Sensor
  - pin: D4
    update_interval: 700s
  - platform: dallas
    address: 0xd901192927c1d028
    name: "Pool Temperature"

Then click on Install the I chose to do the install wirelessly since it's not plug to Home Assistant anymore

Waiting a bit and when it's done, distance begin to be measured (last lines)

Home Assistant integration

Once the ESP flashed we can add stuff in Home Assistant