The Sewer Jet Gazette advises that you use a sewer jet attachment on a pressure cleaner or a mechanical drain cleaner to unclog a main sewer drain. First, though, you need to find a proper access point, which is generally a main drain cleanout opening located in a basement or outside the house. They are generally on horizontal or vertical pipes with round caps with a square fitting on top.
The Sewer Jet Gazette states that a clogged main sewer drain is indicated when drains in more than one room do not drain properly. If left clogged, sewage or other materials from further up the line can be forced out of drains inside the house.
Given the hazardous nature of the materials in sewer drains, this problem must be resolved promptly and with care. Only unclog a main sewer drain with fluid-resistant work gloves and eye protection. Electric pressure washers should be used with ground fault circuit interrupters to avoid electric shock. Gas-powered units should only be operated outside using and extension hose if needed.
According to the Sewer Jet Gazette, mechanical drain cleaners and sewer jets each have advantages and disadvantages. Mechanical drain cleaners are readily available and, with skill, can break up very tough obstacles. Sewer jet attachments are simpler and, when bought for a pre-existing pressure washer, less expensive.