Do you need a plumbing license to provide a drain cleaning service?

No you do not need to be licensed as a plumber to clean drains. Each city and town may require you to buy a vendors license but no plumbing skills needed.

do you need a plumbing license to provide a drain cleaning service?

Perhaps not a plumbing license but they nay require a license to operate. Depends on local codes. Call your local building department and ask. Good luck in your new endeavor. Tom

In my area of operation, you would need a Business License only, not plumber's license. However, if the sewer line you are servicing needs any kind of repair than you would need C-36 plumber's license - other wise City would not issue permits to you.

Just curious... what is a C-36 license? Are there various grades of plumbers licenses?

C-36 is Plumbing Contractor. For more info on licensing in California, go to www.cslb.ca.gov.