English to Russian Other Construction / Civil Engineering

The water in the tank becomes stagnant when not used for fire control.
For this reason, it is recommended to renew part of this water on a
regular basis. Best practice is to have two tanks – the fire water tank and
the operating raw water tank (used for water treatment etc). Raw water
should enter the fire tank from the top and through a pipe from its bottom
to overflow on the top of the operating tank.
By using this method the fire tank is always full and the water is flowing
continuously from the fire tank to the operating tank.
НЕПОНЯТНО, ОТКУДА ПОСТУПАЕТ ВОДА И КУДА ОНА ПЕРЕЛИВАЕТСЯ