Measure water level in cistern, without external power (battery only)

Hardware
1

Hi guys,

I’ve been reading around this topic and haven’t found a good solution to my issue. I want to measure the water level in my cistern, this is quite common and many people have written guides on this with various solutions like water pressure, ultra sonic…

What I am missing is a way to measure the level without external power because I have no additional outlet in the cistern (hard constraint). I’m looking for something that can be battery powered (pi?), only need power for 3-6 months during the summer, and can recharge mid-summer without issues.

I have little to no idea about technical stuff, but would rather spend some money on pre-built devices.

Any idea how I could achieve this? :heart:

2

Do you want to sent the data to HA?
How far away is it from your receiver?

3

Either HA or any cloud provider that has an established api with HA, or something like that.

It is about 3m to the inside of the house where I could set up a router if the device required one.

4

3m from the house and no power??

5

Yes, it is what it is…

6

Extension cord not possible?

7

No, the above are hard requirements that cannot be changed

8

Can the device be outside the cistern with just the sensor inside?
Is there a size constraint on the device and sensor?
Can solar panels be used?

A large USB powerbank of 30.000mAh can keep a device running for a long time and with some cheap solar panels it can run even longer, maybe even “indefinitely”.

9

If you only need to update water level like every few hours, you could use battery powered esp32 board flashed with esphome. Program it to stay in deep sleep for some hours, wake up, measure water level, if changed update to HA and go back to sleep.
So it would stay like 99.99% of time in deep sleep.
image

1 Like
10

Oh wow, I hadn’t seen that one before! That looks super promising. (I ordered two on ebay already)

The second question would be how to measure the water level. Any idea what the easiest way would be to do that? I don’t need fancy stuff that has high precision. ±10cm doesn’t matter at all

11

Mh, I can add a Powerbank, yes. I think size is not the biggest issue here. External power from solar panel - I cannot do that 🫨

12

I think esp32 with battery/solar panel would be best.

You can set it to check every 1-2 hours and then go into deep sleep in between.

13

Depend on many things, most importantly water min max height.
There are ultrasonic, infrared, capacitive, pressure, float sensors etc.

Also ideally it has to draw 0 power when not measuring, so it should be turned off when in deep sleep. In practice, ideally it should draw so little current that you can power it directly from Gpio pin.

Like this, if max 4m water column height is in your range. Newer tried but for $1 worth to try…
https://www.aliexpress.com/item/33002133490.html?src=google

14

I have like 3 meters height with up to 5000 litres of water, so 4m is enough.

But what do I do with this item? It unfortunately does not say anything on aliexpress what type of device it is so that I cannot really google for it :frowning:

15

Pressure sensor 0-40kpa, which equals 0-4m water column. you only need tiny pipe out of your cistern lower part. I repeat, I have never tried this. Just google “Digital Barometric Pressure Sensor Module 0- 40 KPa”

"Description
Report Item
Specification:

Voltage: 3.3 -5 V

Pressure: 0 -40 KPa

The module uses a high-precision AD sampling chip and a 0-40KPa Air pressure sensor. It can be connected to a 2.5mm tube and detects water level and other pressure.

5K ohm resistance bridge sensor, the specific pressure value needs to be calculated. "

16

I just don’t understand how I would put that thing under water while it is itself supplied by 3.3V 🫨🤷

17

What would you have suggested if there was a power supply available?

18

You have to put the tube under water, not the sensor or the esp.

19

And I don’t understand your question.
You wire that module to Esp32 board (3.3V). You connect small tube (like micro drip irrigation hose) from bottom part of your cistern to sensor. I expect you have some threaded connections at the bottom part. Sensor and Esp can be meters away from cistern. Not under water.

20

What would you have suggested if there was a power supply available?

Something more robust:
https://is.gd/49aBaZ