If you don't care about precision (and depending on what your pipes are made out of), you could make a DIY version of that sensor (that you could wrap around th

If you don't care about precision (and depending on what your pipes are made out of), you could make a DIY version of that sensor (that you could wrap around the pipe, rather than having to cut it to put it inline). https://www.youtube.com/watch?v=TR0baWuB6v4 https://www.youtube.com/watch?v=TR0baWuB6v4