Rob Waghorn
Hi Gracy. From what you have said id say there is a blockage out side. If there are inspection chambers then that would need to be checked and cleared. As the downstairs toilet it the lowest point that is why water gluggs and the level rises. Depending on the age of the property there should be inspection chambers and i would advise putting the job on rated people with a budget of under £100. Once cleared the drainage engineer should be able to give you remedial advise. Hope this helps.. Robert. Aspire plumbing and heating.
