Hi. During recent house renovations waste plaster/cement in water mix form has been disposed of in the kitchen sink and has built up (now in solid form) in the upvc pipes. The 'u' bend I have cleaned but the seems to be more blockage further along the system, which slows the water outlet flow. When the washing machine drains, this water back-flows into the sink! To make the matter worse, the pipe runs behind the kitchen units which makes manual clearing difficult unless the kitchen units are removed!
Is there any proprietary chemical product available that might dissolve the plaster/cement without dissolving the upvc pipes too?
Many thanks,
Mary.