Microbore pipes are pipes smaller than 15mm. Often the diameter is either 10mm or 8mm.
These come in both copper and plastic.
Power flushing has a hard time dealing with microbore systems. Many larger companies often refuse to power flush microbore - or - they do not give any guarantees if they do, leaving home owners with a “gambling situation”.
Powder Flush was designed for cleaning microbore systems. The technology has been refined and adapted over many years. We rarely fail, even on the worst case scenarios.