Sewer Laterals and Drainage   

We’ve had a number of office discussions about water-related issues since the first “atmospheric river” passed our way, and I heard something about sewer laterals that I wanted to pass along.

A sewer lateral is the underground pipe that takes wastewater from your home to the city sewer line. You probably know that when you sell a home in Berkeley, the sewer lateral needs to be brought up to current standards, either before or soon after a sale, unless there is a compliance certificate already on file.

The reason this is a requirement is not to address waste leaking from the laterals into the ground.  Instead, the issue they’re targeting is rainwater entering through cracks in older sewer laterals, which is then carried to the wastewater treatment plant, where it can overwhelm the system.

At a recent office meeting, John Karnay (one of the owners of the Grubb Company) pointed out that some old, cracked sewer laterals could be functioning as de-facto French drains, letting rainwater in and carrying it away from the property. If that was the case, when the lateral is replaced, that drainage channel would be gone (because the rainwater can’t get in when the pipe is no longer cracked), and so it’s possible some properties with new laterals could see water building up in new places.

This is mostly theoretical, but it’s not a bad idea to keep an eye on your property’s drainage for a while after the sewer lateral has been replaced.