The mend of the line

By Marie-Eunice Alarcon

Sydney residents are in danger of sewerage contamination as leaky 40-year-old drain pipes are left in disrepair.

Earthenware clay pipes, common to housing sewerage systems built before 1970, are cracking and causing domestic sewerage pollution.

Master builder and renovator Paul Lawrence says old houses across Sydney, some of which share a main sewerage line, are at risk.

“There are houses in Balmain for example that have their own drain pipes but are all connected to each other by one sewer main on the street,” he said.

“So a blockage from just one of the pipes could turn into a problem for all those houses. Once they get worn they clog the drainage system, flies and insects get in or worse tree roots start to feed on the sewerage. You could start a business just draining pipes.”

David Cox from Water Services Australia said: “A leakage could be occurring without the property owner even knowing.”

But he said he did not believe that it amounted to a case against clay piping.

“There are VC clay piping in drainage systems laid by the Romans that are still around,” he said.

Mr Cox believes the main problem is in the jointings. He said that modern jointing techniques like plastic couplers, rubber seals or a rubber end joint are very good. But clay pipes have fallen out of favour with plumbers because plastic PVC pipes are longer and don’t need as many joints.

Sydney Water’s Michael Charlton said: “Sometimes we find the older earthenware pipes don’t need much changing at all just because they are the right size and are in good condition.

“There are 21,000 kilometres of water mains and we service four and a half million people.”

Hydrogen Sulphide found in sewerage as ‘highly acidic’ and able to ‘dissolve cement from concrete’, according to air purification system manufacturers Bio-Oxygen.

“It’s not uncommon to find caverns you can climb into caused by leaking sewers systems,” said plumber Gareth Jobe.

“I can remember as an apprentice when a whole house started breaking in two and started floating away with me under it.”