Noise the landlord can’t shrug off
When the noise comes from the landlord directly — or from building equipment the landlord controls — you generally have a stronger position, because the landlord is responsible for their own conduct and their own systems.
This can include a landlord who lives on-site and is disruptive, ongoing loud maintenance at unreasonable hours, or noisy building equipment such as a failing HVAC unit, pumps, or machinery that runs loudly day and night. Persistent, unreasonable noise from these sources can interfere with your right to quiet enjoyment, and equipment that is malfunctioning may also be a repair issue.
Report the problem to your landlord in writing, describe the noise and when it happens, and explain how it affects your use of your home. Keep a copy and a log of incidents.
Because the landlord controls these sources, they usually cannot simply shrug the problem off the way they might for a distant neighbor. If your landlord will not address serious, ongoing noise they are responsible for, a free, confidential review can explain your options.
This is general information about California tenant rights, not legal advice. Every situation is different.