How to tell who’s responsible for a drain
A slow drain is the tenant's responsibility only if the tenant clearly caused it. Recurring slow drains, backups affecting several fixtures, or blockages in the building's pipes are the landlord's responsibility.
Landlords sometimes try to charge tenants for drain problems that are really about old or failing plumbing. The cause and the pattern matter: a one-time clog from something washed down a drain is different from drains that back up again and again, or all at once.
If the problem is in the shared or structural plumbing — which no tenant controls — it belongs to the landlord. Be cautious about accepting a repair bill or admitting fault before you understand the actual cause. If your landlord is pinning a building-plumbing problem on you, a free, confidential review can help you understand what is fair.
This is general information about California tenant rights, not legal advice. Every situation is different.