Licenses That Complement a Plumbing License (2026)

A plumbing license is one of the most valuable trade credentials you can hold. But if you want to increase your earning potential, take on bigger projects, and make yourself indispensable to clients, pairing your plumbing license with complementary certifications is a proven strategy. This guide covers the four best licenses and certifications to stack with a plumbing license — and why each one makes sense.

1. HVAC Technician License

Of all the licenses you can add to a plumbing credential, an HVAC license is arguably the most natural fit. Both trades deal with mechanical systems in residential and commercial buildings. Plumbers already understand pipe routing, pressure systems, and building codes — skills that transfer directly to HVAC work involving refrigerant lines, ductwork, and hydronic heating systems.

Most states require a separate HVAC license, which typically involves completing an apprenticeship or training program and passing a trade exam. You will also need an EPA Section 608 certification to handle refrigerants. The timeline varies, but experienced plumbers often find the HVAC curriculum more accessible because of shared foundational knowledge. Check our HVAC licensing guide for state-specific requirements.

2. General Contractor License

If you want to move beyond individual service calls and manage full renovation or construction projects, a general contractor license is the logical next step. As a licensed GC, you can bid on larger projects, hire subcontractors, pull building permits, and oversee the entire scope of work — not just the plumbing portion.

For licensed plumbers, the transition to general contracting is smoother than for most other trades. You already understand building codes, inspection processes, and project timelines. The additional knowledge you need is primarily in business management, contract law, and coordination of other trades (electrical, framing, finishing).

General contractor licensing requirements vary significantly by state. Some states require a trade exam, a business and law exam, proof of insurance, and a financial statement. Others have minimal requirements beyond registration. Visit our general contractor licensing guide for details on your state.

3. Fire Sprinkler Technician Certification

Fire sprinkler installation and maintenance is a specialized niche within the plumbing world. The work involves designing, installing, inspecting, and maintaining fire suppression systems in commercial and residential buildings. Because sprinkler systems are essentially specialized pipe networks, licensed plumbers have a significant head start in this field.

Licensing for fire sprinkler work varies by state. Some states require a separate fire sprinkler contractor license, while others allow licensed plumbers to perform this work under their existing plumbing license with additional training. NICET (National Institute for Certification in Engineering Technologies) certifications are widely recognized in this field. Training typically covers NFPA 13, 13D, and 13R standards for sprinkler system design and installation.

4. Backflow Prevention Certification

Backflow prevention is a specialized certification that pairs perfectly with a plumbing license. Backflow preventers are devices installed on water supply lines to prevent contaminated water from flowing back into the public water supply. Every commercial building and many residential properties are required to have these devices tested annually by a certified tester.

For licensed plumbers, adding a backflow prevention certification is one of the easiest and most cost-effective ways to expand your service offerings. The certification typically requires a training course of 32 to 40 hours and passing an exam. Many plumbers complete the certification in a single week.

The American Backflow Prevention Association (ABPA) and the American Society of Sanitary Engineering (ASSE) are the two main organizations that offer backflow prevention tester certifications. Most states and water districts accept certifications from either organization.

Which License Should You Add First?

If you want the fastest return on investment, backflow prevention certification is the clear winner. It takes about a week, costs relatively little, and immediately opens up a stream of recurring revenue. If your long-term goal is to grow a larger contracting business, pair your plumbing license with either an HVAC license (for residential service expansion) or a general contractor license (for project management and larger jobs).

Frequently Asked Questions

Can a plumber do HVAC work without a separate license?

In most states, no. Plumbing and HVAC are regulated as separate trades, each requiring its own license. However, there is significant overlap in the skills required, and some states offer combination or mechanical contractor licenses that cover both. Check your state's requirements on our HVAC licensing page and plumbing licensing page.

How much more can I earn with multiple trade licenses?

Earnings depend on your market, business model, and how effectively you leverage multiple credentials. Plumbers who also hold an HVAC license or general contractor license typically report higher annual revenue because they can take on a wider range of projects and offer bundled services. The exact increase varies, but the ability to self-perform multiple trade scopes on a single project meaningfully improves profit margins.

Is backflow prevention certification worth it for residential plumbers?

Yes. While commercial properties generate the most backflow testing volume, many municipalities also require backflow preventers on residential irrigation systems and fire sprinkler connections. The certification is inexpensive and quick to obtain, and the recurring annual testing revenue makes it worthwhile even for plumbers who primarily serve residential clients.

Do I need to complete another apprenticeship to get an HVAC license if I am already a licensed plumber?

It depends on your state. Some states require a full HVAC apprenticeship regardless of your existing plumbing experience. Others give credit for related trade experience, reducing the required apprenticeship hours. A few states allow experienced plumbers to sit for the HVAC exam with documented work experience in lieu of a formal apprenticeship. Contact your state's licensing board for specific crossover credit policies.

Next Steps

Start by checking the specific licensing requirements in your state for the credential you want to add. Each state has its own rules for education, experience, and exams: