Requirements guide
Plumbing failures can cause massive water damage. Here is what coverage to require and what to verify before a plumber starts on your project.
Water damage is one of the most expensive property claims in construction. A supply line failure, a missed connection, or a backflow event can cause six-figure damage before anyone notices. Plumbers carry risk that extends well past the day they leave the site.
Beyond the standard policies, watch for water damage sublimits buried in the GL policy and ask about pollution liability if the scope includes drain cleaning chemicals or sewer work. Here is the full picture.
| Policy | Typical limit | Why it matters |
|---|---|---|
| General Liability | $1M per occurrence / $2M aggregate | Covers bodily injury and property damage including water damage from faulty plumbing work. Check for sublimits on water damage specifically. |
| Workers' Compensation | Statutory limits | Required for any employee. Plumbing involves confined spaces, hazardous materials, and physical strain. |
| Commercial Auto | $1M combined single limit | Plumbers typically drive to job sites with a truck full of pipe and tools. |
| Umbrella / Excess Liability | $1M to $2M+ (project-dependent) | Common on commercial, multifamily, or large residential projects where water damage exposure is high. |
| Pollution Liability | $1M (if required) | Needed if the scope includes drain cleaning with chemical agents, sewer or septic work, or any hazardous material handling. |
Typical limits reflect common GC contract requirements as of 2026. Actual requirements vary by contract, project size, owner, and jurisdiction.
When you receive the certificate of insurance from a plumber, check each of the following before approving the document.
Water damage sublimits
Some GL policies cap water damage claims at $50,000 to $100,000 per occurrence, even if the policy otherwise shows $1 million limits. A single burst pipe in a multifamily building can easily exceed that. Ask for the declarations page to check for sublimits.
Completed operations for leak claims
Slow leaks behind walls are often discovered months or years after the plumber has left. Completed operations coverage in the GL policy covers post-project claims. Confirm it is included and not set to expire at the next renewal.
Pollution exclusion on drain cleaning
Standard GL policies often have a pollution exclusion that can be interpreted to bar coverage for chemical drain-cleaning products. If your plumber uses caustic or enzymatic chemicals, verify the policy does not exclude this or obtain a pollution liability endorsement.
Backflow and cross-connection
On commercial projects, backflow prevention is both a code requirement and a coverage trigger. Some GL policies exclude contamination events from cross-connections. Confirm coverage if the scope touches potable water lines near industrial or chemical systems.
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At minimum: general liability ($1M/$2M), workers' compensation, and commercial auto. High-water-exposure projects often require an umbrella. Sewer and drain-chemical scopes may also need pollution liability.
A GL policy showing $1M/$2M limits may still cap water damage claims at $50,000 or $100,000. On a multifamily or commercial project, a single supply line failure can cause far more damage than that. Always ask for the declarations page.
Not always. For standard install work with no chemical use, standard GL is usually sufficient. If the scope includes chemical drain cleaning, sewer work, or handling of hazardous materials, pollution liability is worth requiring.
Long enough to cover your project's warranty or defect-discovery period, often one to two years after substantial completion. Confirm the coverage is renewed along with the main policy.
This guide reflects typical GC requirements and general industry practice as of June 2026. Insurance requirements vary by contract, project type, jurisdiction, and owner. CoiLoop organizes documents and reminders and does not provide insurance advice or certify coverage.