In the history of mankind, the development of systems of escape goes back to the distant past. In ancient times, in the countries of Rome, Greece, Egypt, and later in the European regions, the large-scale use of collector-drainage systems was established. The article presents hydrodynamic processes occurring in open drainages. The problems that arise in the design and construction of open drainages are highlighted. The non-wash rate table given in the building codes and regulations was analyzed. The formulas given by the authors for determining the rate of non-washing were studied. Scientific research on the design of open bed collector systems based on the rate of non-washout has been carried out and the results are presented.