We have an underground storage tank, which was used for irrigation when the surrounding area was an orchard before the house was built. It’s not as deep as it used to be, but still holds around 2000 gallons of water when full. It’s filled from half of our house roof, and all of the garage roof. There is a submersible pump in it which we use to water the garden.

Measuring the water depth has always been a challenge, and you can just see a white measuring stick – but all the markings on this faded over time!

Last year, I purchased an ultrasonic depth sensor which worked fairly well but wasn’t robust enough to survive outdoors.

So this year, I bought an industrial pressure sensor, which now sits at the bottom of the tank:

I found an small microcontroller board that has a suitable input for this – this board also has integrated WiFi so it can send the measurements back to the house.

This sends the data to some logging software running on our Raspberry Pi based server.

This works just fine, but being a pressure sensor, the recorded level varies slightly with atmospheric pressure changes. So a bit more digging found this little board, which measures barometric pressure and temperature:

I found a design for a small “Stevenson Screen” to hold this board, which I printed on my 3D printer:

This also connects to the WiFi board.

You can see the results from these sensors by viewing http://home.wsn.uk:5555 username ‘view’, password ‘view’. Click on the icons to see the graphs showing these inputs change.

The next task is to adjust the Water Level reading with atmospheric pressure!