Nolik wants to join his Simka and go to the laboratory of Professor Eugenius to complete an important task she will be doing with Fire and Digit. Simka doesn’t want him to go because she thinks he is too impatient to handle the work. Nolik wants to prove to Simka it isn’t true and asks her to give him a test to prove he is capable of demanding work. Simka challenges her brother to track 100 glasses of water passing through the water filter in the kitchen. At first things are going well as Nolik secretly observes different family members come into the kitchen to use water: Dad drinks a glass of water, Mom pours water it into a pan for cooking, Chewsocka's empty water bowl is refilled… Nolik thinks he is well on his way to reaching those 100 glasses, but soon the action comes to a standstill. For the next several hours no one comes into the kitchen at all. When Tom Thomas finally comes in for something to drink, he opens the refrigerator for milk. Nolik convinces him drinking water is a much better choice, and then actually talks him into drinking glass after glass until he is so full he thinks he is going to burst. Suddenly a red light on the filter lights up. Nolik calls Simka on his fixiephone to alert her to the emergency – the water filter is broken! Simka, Fire and Digit arrive and Digit informs Nolik that it isn’t broken at all, that the light is just an indicator that it’s time to replace the water pitcher’s old filter with a fresh one. The filter is replaced and the warning light turns back off, but Tom Thomas hurries out of the room when his body gives him a warning signal of its own that he’d better run to the bathroom!