The design of the slope of the sewage pipe mainly depends on the pipe material, pipe diameter size, water flow characteristics and other factors. The following are some details:

In general, the minimum slope of sewer pipes is between 0.002 and 0.003.

For pipes made of specific materials, such as plastic pipes, the slope is usually set at 0.002, while for other materials, a slope of 0.003 is required.

In some cases, such as sewage pipes inside public buildings and residences, slopes are typically designed to be between 1 and 2%.

For reinforced concrete pipes with a diameter greater than or equal to 150 mm, acid-resistant FRP pipes, etc., the slope can be appropriately lowered, but it is necessary to ensure that the normal flow can still be maintained in the case of low water flow.

In addition, in the straight pipe section, the slope design value is usually between 0.5% and 1.0%, while in the pipe elbow, tee, cross, reducer and other throttling pipe, the slope design value should be greater than the slope design value of the straight pipe section, generally determined by 2% to 5% between.