Device to know if a toilet tank is full

Hi all,

I live in an old house that has old toilets. Every once in a while the handle of one of these toilets gets stucked, which makes the flapper stay open and the water keeps running. I’m tired of wasting water, so I want to install a zigbee device to check if the toilets’ tanks are full or empty.

I’ve sticked Aqara water leak sensors near the top of the tank, where there’s still water when the tank is full. Given that the regular state of the sensor is “detected” (the tank is full), I’ve created an automation that sends me a notification when the sensor is dry for more than 5 minutes (it means that the tank is empty). The problem is that after a couple of months, the sensors stop working. I guess that this happens because they aren’t meant to be submerged for long periods of time.

Is there any way I can solve this with an already existing product? If that’s not the case, can I solve it with a modified version of an existing product? I’d like to avoid having to put together one because I haven’t got experience programming zigbee boards.


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You can use the aqara sensors you mention. They have two screws on the back where you can attach wires. You put the sensor on the outside of the tank and then hang the wires into the tank. I do this for monitoring my sump pump and the sensor has been working for well over a year.


Why not use a float switch?


Monitoring water flow in a house is a real challenge. Floor based leak detectors are a good ‘last line of defense’ , however having something that can detect a leak in a faucet or toilet is a missing component. As you note, reliability of these sensor over a long period of time is very important, most of our home automation stuff ‘fails wrong’ and then you are left months or years out with being SOOL. At the core is that flow sensors that can detect these leaks require power usually beyond batteries. Getting mains power and a DC wall wart near every possible leak source is beyond cost effective.

About the only cost effective and useful way is to look at a flow sensor at the water inlet to the house. There are a couple of off the shelf solutions, with the Moen Flo being probably the closest thing to a ‘gold standard’ (with a ‘gold’ price). You still need to run power to the flow sensor, however ‘at least, it is just one point’. This is not going to tell you where the leak is, just that there is a leak. It is possible to do a DIY flow sensor at the house entry point instead of a off the shelf product. The other ‘plus’ to a solution like this, is you can have a controllable turn off valve for all house water. This can not only save you from some serious flooding heartache, it may offer you some insurance premium saving to offset the install cost.

Good hunting!

Why not just repair the toilets?

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That’s a nice idea! I’ll try it out. Thank you!

That’s great. I guess I can use something like an Aqara Door sensor and adapt the float switch sensor to it. Thanks

That’s an interesting thought on using the door sensor. Since half of the contact sensor is just a magnet you might be able to put the sensor half on the outside of the tank and then play with magnets to find one with the right strength that will trigger the sensor half as closed. Then put the magnet on a float and let it ride up and down with the water level.

I was just thinking of taking out the magnet and connecting the terminals to the float switch sensor, similar to what this guys does it with a bed sensor

What float switch sensor are you using and will it really show if water is fully shut off? In the past when I’ve had a similar issue with the tank not shutting off, the tank was mostly full and the flapper just wasn’t seated right so a small amount of water would continue to leak into the bowl. Replacing the flapper fixed the issue.