By decomposing on the floor all the details of the future sewer, you need to lubricate the joints with a thin layer of any lubricant or oil. This will facilitate the assembly. Having kept the necessary slope, you need to collect all the details in a single design. In direct sections of the sewer, you need to lay stops through each meter so that it does not bend under the weight of water. Otherwise it will violate the tightness of the connection.