Problem: I own a home that I'm not always at, It rains there a lot and I need a way to monitor if there is rain by using a sensor so i can turn on a pump to move the water away from my house.

Solution: I'm using a raspberry pi to do all the heavy lifting. So I have a relay along with code that talks to everything. The raspberry pi is the easy part of this. I'm a CS not a EE.

My question: I'm looking for a sensor that will last outside without any maintenance, for up to 6 months. That will sense if it is wet and talk to the raspberry pi. I found a sensor.


That I'm pretty sure i can hack up, but haven't found anything that looks a bit more "long term." For my application, i think im going to really test the hell out of this, if it breaks i would have to monitor my house physically with a web cam to see if its flooding. If i found a sensor thats reliable, i could save time by not worrying about it at all, and letting the sensors + raspberrypi + notifications to do all the "worrying" for me.

  • 1
    \$\begingroup\$ You might want to take a look at electronics.stackexchange.com/questions/55400/… A similar approach could be used. \$\endgroup\$
    – Matt Young
    Commented Jul 17, 2013 at 22:48
  • 3
    \$\begingroup\$ You know this is exactly the problem a sump pump solves, right? \$\endgroup\$
    – Phil Frost
    Commented Jul 18, 2013 at 1:59
  • \$\begingroup\$ A sump pump would do the trick, but I would still like to make sure its working over time. Either way I would like to have some type of notification without any interaction by human. \$\endgroup\$ Commented Jul 18, 2013 at 18:15

2 Answers 2


To begin with, there are several technologies for water sensing, with varied degrees of robustness. See these questions: Are there existing electronic sensors that can sense if underwater or not? and How does this soil moisture sensor work?, as well as some others on this site.

Some of these options, including a variant on the Grove sensor in the question, can be made robust enough to last years - simply by environment-proof epoxy / conformal coating of the entire sensor circuit other than the sensor strips themselves. This is one of the methods used by remote weather monitoring stations.

The soil moisture sensor is particularly attractive, as those are designed to be deployed for years of operation anyway.

Given that it is rain that needs to be sensed, an alternative approach would be this:

  • Place a microphone close to a window or touching the attic ceiling (if an accessible attic exists) of the house to be monitored.
  • Capture the sound, and code a set of filters and thresholds such that a trigger is generated on the patter of raindrops
  • Use this trigger to actuate pumps or other equipment, or even to send captured images back to you for post-facto verification.

A setup like this would work: http://hackaday.com/2013/04/30/sump-pump-alarm-sends-text-message-as-water-rises/

You may also want to get a backup power supply, so you can still power your pump (for a little while, at least) in the event of a power failure.


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