It's always best to hire local plumbers in San Francisco when you have a plumbing problem. When you hire a local plumber you are hiring one that knows local San Francisco plumbing code and that is very important. The codes in San Francisco can be a little more stringent than in other cities. So the problem you could face if you hire a plumber from another city is they may not get the work done to local code. This can be a problem especially if the work is not permitted, although it is not legal to have plumbing work performed over $500 without being permitted it does happen. The problem a home owner could face is if they are trying to sell their home, at that point the work may be red tagged and may require another plumber to fix the work that should have been done right in the first place. So the benefit of hiring a local San Francisco plumber is they are more familiar with local codes and will generally perform the plumbing work in accordance to code.