How to calculate the commission of municipal water supply and drainage design

30% is the designer's commission. The calculation base is the contract price, of which about 30% is the commission of full-time professional designers, and the remaining 70% is the company operating expenses+company tax+boss income. Drainage design refers to a kind of drainage design based on highway grade, precipitation, longitudinal slope of the route and other factors, combined with subgrade, bridge and culvert structures.