Initially, the sensor is designed to determine the moisture content of the soil (not in the air!). But I use it to determine the presence of water directly on the electrodes. Sensor electrodes are located directly near the floor in areas where leakage is possible (a plurality of electrodes connected in parallel). The electrodes are immersed in water, in case of leakage. Believe me 
, the electronic circuit is working properly. Simple tests show it. Earlier, the same scheme worked well. My project, but without the use Blynk - (ru) https://geektimes.ru/post/259086/ sensors used are the same.