Contact sensor for sump pit?

Hello, I have an idea to monitor my sump pit water level in case my pump fails. At first I was planning on just putting a water sensor in the pit near the top but I’m worried moisture will build up on contacts and trip it falsely. I have the pit covered. Also, I have my softener waste hose in the pit and it splashes when discharging. So, I have another plan and need some advice.

I have an idea to put a magnetic float switch in the pit and hook that float switch to a contact sensor. Can I use the mimolite to do this? If using a regular contact sensor like for a garage door not sure how to hook that up? Thanks for any input.

Here is link to float switch I saw

I wouldn’t use the MIMOLite in this use case, but instead an Ecolink/Monoprice open/close sensor via the internal contact terminals. It’s much cheaper and that will work. I do that for a doorbell, mailbox, and 3 lock sensors. Your float switch will work perfectly.

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I use this water sensor for my sump pit to alert me in case the pump fails. From the description there should be no issue with frequent water contact because it can also be used as a sensor to monitor low water level for pools and the sensor is constantly submerged.

Aeotec by Aeon Labs DSB45 Water Sensor, Small, White


I use the Utilitech water sensor with leads on my covered sump pump. Also, I drain my hot water heater into my sump twice a year. (yes I know you aren’t supposed to put scalding hot water through the pump, but I do it right after everyone has their showers) So I was worried about splashing also. What I did was I cut the taller section of a plastic easter egg in half (long ways) and it acts as an umbrella for the water sensor. My AC, humidifier, dehumidifier, water heater and Tile drain system all feed into my sump and I’ve never had a moisture issue trip the sensor falsely.

Maybe try that.

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Thanks for all the suggestions, much appreciated!

I like the device I linked to at the bottom of this post because it allows you to monitor the frequency that it runs and also use it as a makeshift water sensor:

The water sensor aspect won’t work with all sump pump configurations, but the vibration detection allows you to use CoRE to receive notifications if it’s been too long since it last ran. That way I’ll still get notified if my zwave network goes down for whatever reason because CoRE runs in the cloud.

I also have other water sensor probes hanging in the pit and I’ve never had an issue with condensation, but I recommend testing them every once in a while to make sure.

If I used the open/close sensor using the internal contact terminals can you explain how I would hook things up? I’m having a hard time visualizing how I would hook the float switch up and do I put the 2 parts to the sensor together or apart? Thanks.

Sure, not problem. The Ecolink/Monoprice open/close sensors have internal screw terminals. Just attach each wire coming from the float sensor to each screw terminal. Depending how the float operates, when it rises and closes the connection inside the float, the sensor should say Closed. Here’s an image of what the “guts” look like (you don’t need the magnet part of the sensor anymore):

Click on it to open it a little bigger, and then click on the image again to enlarge it even more:

If I wanted to use this idea for my battery back system would that work also? It has a similar float switch as the ones linked to in the OP. My concern would be the float switch is only closed for such a short period of time that it wouldn’t register with the open/close sensor.

I kind of think monitoring if there’s 12V on the power line to the sump pump would be preferable but not sure how to do that either. Probably using ThingShield or maybe MIMOlite.

What do you consider short? I used the same setup pictured above for a doorbell, and that had a super short duration as you can imagine.

You could use a simple Iris wall plug to detect power consumption instead of a MIMOLite. Assuming it’s rated for that kind of power draw. Also look for Aeon’s Smart Outlet.
The gen 1 device with the cords on each end (can’t remember the model number). I have those on all my frigs, washer/dryer, and microwaves.

Well the pump kicks on then as water is pumped out the switch reopens. I bet it’s longer than a doorbell press though so I’ll give it a try, thanks!

The wall plug wouldn’t work in this case. The way a backup sump pump works is there’s a wall wart going to a circuit board, then connections from the circuit board to an automotive battery and to the sump pump. Ideally I’d monitor the 12v lines from the circuit board to the sump pump but I can at least monitor when the float closes. Now to get the correct sensor!

Maybe I’m way over thinking this and should just be using the float switch as a normally open switch then monitoring with this:

The Ecolink sensor will do the same thing as the Aeon device.