Cleaning out your drain pipe yourself with a drain cleaner might make your sewer pipe problems worse. If your sewer line has collapsed, pouring drain cleaner down it will not improve the flow of wastewater. Instead, the chemicals will sit in the pipe and dissolve it. This will result in the chemicals penetrating the ground beneath the pipe. This corrosion might increase your replacement costs as well.
Also, if you turn on the water to flush the pipe after having poured the cleaner, the water, containing chemicals, can back up, and could cause injury and damage.
Instead of trying to clear the pipe on your own, it is best to consult a professional plumber at Real Fix.