Best Licensed Plumbers in Diamond Bar, CA
21 plumbing companies registered in Diamond Bar hold current CSLB licenses, verified against official records as of August 17, 2026. The 8 below are the top-ranked, ordered by workers' compensation cover and years licensed.
- 4,272 active C-36 plumbing licenses in Los Angeles County; 21 registered in Diamond Bar
- 10 of Diamond Bar's 21 licenses (47.6%) carry current workers' compensation cover, not liability insurance; a blank usually means an owner-operator with no employees
- Median time licensed in Diamond Bar: 24 years
- Longest Diamond Bar licensure: since 1991
- 375 county licenses reach their expiration date within 90 days
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- Verified
- August 17, 2026
- Licensed since
- 1993
- Phone
- (213) 798-4693
- Verified
- August 17, 2026
- Licensed since
- 1997
- Phone
- (714) 620-5670
- Verified
- August 17, 2026
- Licensed since
- 1998
- Phone
- (626) 731-5406
- Verified
- August 17, 2026
- Licensed since
- 1999
- Phone
- (714) 293-9827
- Verified
- August 17, 2026
- Licensed since
- 2001
- Phone
- (909) 248-5069
- Verified
- August 17, 2026
- Licensed since
- 2001
- Phone
- (909) 631-9805
- Verified
- August 17, 2026
- Licensed since
- 2006
- Phone
- (714) 615-2104
- Verified
- August 17, 2026
- Licensed since
- 2012
- Phone
- (909) 538-9188
Compare the top 6 at a glance
| Company | License | Workers' comp | Licensed since |
|---|---|---|---|
| C S D M Inc. DBA Cal Steam Company | #674646 | On file | 1993 |
| C - Thirty - Six Inc. | #739644 | On file | 1997 |
| Jh Builder And Remodeling Inc. | #751479 | On file | 1998 |
| Zip Renovation & Air | #762505 | On file | 1999 |
| Service Wizards | #797071 | On file | 2001 |
| Kenneth Daley Heating & Air Services | #798187 | On file | 2001 |
Los Angeles County plumbing licensure at a glance
California licenses contractors by classification and CSLB publishes one on every record, so supply can be counted exactly: 4,272 active C-36 plumbing licenses in Los Angeles County, 21 of them registered in Diamond Bar. CSLB also publishes a real original issue date, which Washington's registry does not, so tenure is measurable here: the median Diamond Bar license has been held 24 years, and the longest-standing one dates to 1991. 10 of Diamond Bar's 21 licenses (47.6%) carry current workers' compensation cover in CSLB's file. That is employee injury cover, not liability insurance, and a blank usually means an owner-operator with no employees - lawful, and not a mark against anyone. The contractor bond is not a signal here: 4,270 of the county's 4,272 licenses carry the same $25,000 bond California sets by statute. 375 county licenses reach their expiration date within the next 90 days. CSLB cannot link straight to a license record, so every listing above shows its number for you to type into CSLB's license lookup. How we verify.
Plumbers in Diamond Bar: common questions
How many licensed plumbers are there in Diamond Bar?
21 active C-36 plumbing licenses are registered in Diamond Bar, out of 4,272 across Los Angeles County. 21 Diamond Bar-registered companies passed our license verification, and the 8 on this page are the top-ranked of those. Only licenses CSLB shows as CLEAR and unexpired are listed.
Does California license plumbers?
Yes. California licenses contractors by classification, and C-36 is the CSLB classification that authorises this work. 21 active C-36 plumbing licenses are registered in Diamond Bar and 4,272 across Los Angeles County, the longest-standing issued in 1991. Only CLEAR, unexpired licenses appear here.
How do I check a plumber's license in California?
Every listing above shows its CSLB license number. CSLB cannot link straight to a record, so open its license lookup and type the number in: it shows status, expiration, the contractor bond and workers' compensation cover, which 10 of Diamond Bar's 21 currently carry. 375 Los Angeles County licenses expire within 90 days.