Strange as it may seem I failed to find any device on the market that would answer my needs.
There were either expensive systems for water tanks filling in condominiums or various pumps and systems designed for more effective water transfer from the tank into the house. However, there were no available household systems that would control the water feed into the tank.
Thus, I decided to make a device, the modest dimensions of which would give it the opportunity to collect a certain volume of water at minimum pressure in the water feed system, and then, using a built-in pump, transfer this water into the tank.
At the same time, the device must be simple, reliable, efficient, and, preferably, inexpensive to produce.
A separate issue was the connection of the booster box to the water tank.
I wanted to avoid connecting the device to the tank with a separate pipe; therefore I had to make a water feed system running through the main pipe: the booster box would have to be in the middle of the water feed system, collect water at low pressure and pump it through the same pipe into the tank.
Sadly, in order to monitor the water level in the water tank, it was necessary to have a sensor in it.
In addition, it was necessary to control the level of water in the device itself, to be able to control when it has to switch on/off.
Therefore, we have 2 water level sensors and the pump, controlled by these two sensors.
A great task for implementation based on microcontroller.