Clay Drain Pipe Replacement


Replacement of clay drainpipes

In the past, clay drain pipes were the most common pipes used for 100mm as well as 150 mm diameter drainage systems. The advancement of technology led to diminishing of these pipes in the late 1960s. However, the 150mm pipes are still being used in some places for sewer systems beneath buildings of public highways. Usually, construction activities can lead to these pipes being exposed or excavated. Therefore, it cannot be re-laid because it is hard to achieve a watertight condition with clay pipes, unless an expensive mortar joint is done. Due to these challenges, it may be wise for you to replace your clay drain pipes with PVC pipes.

Replacing clay drain pipes with PVC

Clay pipes can be replaced with PVC pipes or the same diameter or smaller as approved by local authorities. In this case, the clay pipes need to be cut and a flexible coupling attached to the end of the pipe. At this point, the PVC pipe is attached to the end of the coupling and bonded together.

Usually, professional plumbers who are approved by relevant authorities do replacement of clay pipes. Therefore, it is important to hire a qualified plumber to ensure that your clay drain pipes replacement meet international standards.
Steps taken by plumber in replacing Clay pipes

  • A reciprocating saw with a carbide blade is used to cut through your old clay pipe at the desired point. The cut should not have any bends. At this point, the plumber cut through and removes areas in the clay pipe that are leading to water leakage.
  • A flexible rubber coupling is attached to the end of the cut clay pipe. The metal strap around the coupling must be tightened properly to avoid leakage of the pipe. Then, a new piece of PVC pipe is pushed onto the other side of flexible coupling.
  • The plumber connects the entire PVC coupling to ensure that water fixtures such as toilet, sinks, and toilets in your home run into this new drainage line. At each coupling, PVC primer is used to prime the inside and the ends of the PVC pipes. The PVC glue is applied to the entire primed areas then the pipes are pushed into the ends of the couplings and hold for 30 seconds.

Tips and warnings

The horizontal pipes need to be placed at a gradient so as to ensure that waste travels down the drain. It important to check the city laws for the right gradient. Usually, the right gradient is an inch per 10ft of the drainage pipe.

In case the new PVC pipe has a smaller diameter than clay drainage pipe, a flexible coupling is used to connect the two pipes together. This coupling must be of the same diameter of the PVC pipe on one end, the diameter of the old clay pipe on the other.


These tips give you an invaluable guide in looking for a professional plumber to replace your old clay pipe drainage system. However, it is important check with the local authorities if the plumber is duly registered.