Codes are not state-wide, they are local. You need to check your city's code.

my city just says adopting CA plumbing code and nothing else

Here you go with the link below that will keep you busy for hours. There is another site that "Enduring" recently linked on this forum, addressing general bathroom design guidelines.

http://starcraftcustombuilders.com/bath.design.rules.htm This site says the minimum distance from the center of the lavatory to the wall is 15". More is better if you got it.

-Babka

Here is a link that might be useful: CA codes

I would like to know WHY there is a rule on the distance from the wall to the center of the sink? What safety issue is involved?

Don't think it is a safety issue, just good design sense. Put a board less than 15" from the center of your sink, move your arms like a chicken...or pretend you are washing something or brushing your teeth. You don't want your elbows to bang into a wall.

-Babka

Yes, but code shouldn't be legislating design.

For safety...yes. Code requires GFI's etc. I don't think the distances are required, just suggested for good design. But I'm probably wrong...here in CA someone ALWAYS knows what is best for me. I don't get to decide.

-Babka

For a two-bowl vanity, it's 15" minimum between the centerlines of the two sinks, as well 15" from the centerline of each sink to the adjacent wall on either side of each sink.

That's an IRC code minimum. Those specific numbers probably won't be found in the actual plumbing code, as the plumbing code is more geared towards the actual plumbing and not the layout. IRC, or the actual building code, is the code that contains minimum space requirements.

As far as code hierarchy, IRC is for the most part the building code that covers the United States as a whole. Individual states then have their state codes. Most states simply embrace IRC as a whole, though some states add some additional restrictions geared towards that state. Example, a state like California may have added sections that address seismic concerns.

Then there is local code. Individual towns or cities may have additional restrictions dealing with their very localized issues. Historical neighborhoods, etc.

For the most part, local and states codes can't relax national (IRC) code requirements, but they can be more restrictive.

Sometimes code is added for political reasons. Example, the plumbers union in Massachusetts has a very strong influence on code there. Same with electricians and the electrical code in Chicago. Restrictions are added to try to make it difficult for DIYers to do any work on their own houses.

sjhockeyfan ... I would like to know WHY there is a rule on the distance from the wall to the center of the sink? What safety issue is involved?

It sets a minimum standard for ergonomic and access space so people don't have to keep re-visiting the issue with each build.

Because some sleazebag builders and/or idiot DIY remodelers would jam two sinks in side by side with zero clearance and call it a vanity. And have toilets with so little clerance they were unusable.

It gives builders a pre-drawn line in the sand so they don't have to argue a client into not cutting corners on spacing ... "because it doesn't meet code" settled many issues for my BIL the renovator.

It gives manufacturers of vanities, sinks and toilets a standard to manufacture to ... saves money.