Filling level of rain barrel in the garden


does anyone have a sensor or idea how to measure the water filling level of a rain barrel in the garden?

Most of my sensors are from vendor “Homematic” and I’m also aware of sensor HM-Sen-Wa-Od. I saw that the minimum height of the barrel needs to be at least 1.1 meter for this sensor to work. Mine is only 80 centimeter in height. So this sensor seems to be not the right one for my use case.

Are there any other solutions or ideas how to implement a wireless solution? Any hardware tip? Maybe via ultrasonic sound or some other technology? It should work with batteries if possible and send the data wireless to my raspberry / openhab.

Thanks for all your creative suggestions!

This fellow used an arduino to build a sensor for an oil tank. My suggestion would be to use a JSN-SR04T module which is waterproof and has a minimum distance of about 20cm. The HC-SR04 module will die after a few weeks from humidity.

I found problems with a number of different ultrasonic sensors and they all died. In the end I used a pressure sensor and this has been sitting in my water butt for 6 years without any problem. I have the pressure sensor at the top of the tank, and this is connected to a tube which is open ended and goes down to the bottom of the tank (I put the plastic tube into a aluminium tube to provide it some rigidity.

Works very well :slight_smile: .

Hey there,

there is a german company that brings out such a sensor :

Best regards

I have used 3 different systems (a pond and two reservoirs)

1-Ultrasonic, with an HC-SR04. As Russel said, that died.Not after a few weeks, took months but it died. Replaced it with I think indeed the JSN-SR04T and that works perfectly.

2-In a system where I just want to know “almost empty” , “half full” or “full”, I installed a pvc pipe going from bottom to top with 3 reed switches in it. I have a wooden ring with a magnet floating on the surface, around the pipe. It stores the last state in case the magnet is in between reed switches.

3-capacitive: I have two insulated plates in a reservoir that form the capacitor of an HC14 RC oscillator. I measure the pulsewidth/frequency which is an indication for the amount of water in the barrel. The plates are just aluminiumcovered with resin.

Mine are not battery operated, but i guess nr 3 would be the most suitable for battery operation.

If you want battery operation… the ESP8266 might not be the best choice, consider an attiny85 in deep sleep with a 433MHz Rf module. The esp8266 spends relatively much time and energy on connecting to network. If you insist on an ESP8266, dont get a wemos or lolin board, get a bare ESP8266-12 module: no led or ftdi chip to feed

I have an rf transmitter plus attiny sending me data 4 times a day, just with a supercap (3F) and a small solarpanel

Maybe a bit late, but:

I use (several) SR04 sensors connected to arduino with souliss and NewPing to meassure the distance to the water-surface.
The value is written to a T_51 typical. in openHAB I have two items to set the min and max “distance” and calculate the filling-level in %

caveats: the NewPing-lib returns cm-values without decimals. so %-steps are rather big when you have just a small difference between min and max

Sorry for bumping up an old question but I’m in the same boat of requirement.

And to my surprise there are quite a few new sensors in town:

This one has 2 transducers instead of 1 therefore has less minimum detection distance as compared to JSN SR04T. It is also completely sealed and waterproof.

Before finalizing on this I had bought another one which was a waterproof modified version of HC-SR04 from here

The 1st one is much more rugged and waterproof as compared to the latter one.

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@Ritesh_Talreja is a spam account. They have posted the same fake advice in multiple forums, including Cayenne MyDevices and MySensors.

Their products might not be bad, but they are masking matketing as advice.

I was looking at different solutions as well (mostly ESP-based ultrasound DIY-projects) but in the end decided for the above mentioned HM-Sen-Wa-Od from Homematic, since I didn’t want to go all-in on something 100% homemade.

Soldering the HM-Sen-Wa-Od together from the individual components was ok-ish. What was however really really (!) difficult was getting it to establish a radio connection with my CCU due to “being 50cm below the surface, trapped in a ferroconcrete dome with a steel manhole cover on top”). What did the trick in the end was replacing the antenna with an external antenna, connected via a 5 m cable, which was then long enough to place the antenna outside of the cistern.

So far it’s doing it’s job. Let’s see how it performs over time in this extreme environment (constantly cold and wet).

In the manufacturer’s forum someone recommended sealing the logic board with a PCB-protective coating, which I also did as an additional protection, since the idea sounded logical to me. So far so good.