In Plain English
Quick Answer
The master valve that shuts off all water to the entire building — the first thing to turn in a plumbing emergency.
Definition
Definition
The valve that controls the flow of water to the entire building, located at the point where the water service enters the structure. Turning off the main shutoff valve stops water to all fixtures and equipment, essential for emergency leak control and major plumbing repairs. It must be readily accessible and clearly identified.
Context
Why It Matters in Bidding
On bids, the main shutoff valve marks the responsibility boundary between the utility service and the building's interior plumbing, which affects how the estimator splits scope, permits, and tap fees. Specifications often dictate the valve type, accessibility, and labeling, and overlooking required backflow assemblies, meter pits, or isolation valves at this point can create costly omissions and inspection failures.
Example
Example
Estimating a tenant fit-out, the plumber confirms the building's main shutoff is in the basement mechanical room, so he prices only branch isolation valves for the suite and excludes any work on the building service entrance.
See Also
Related Terms
FAQ
Questions Contractors Ask
Where does the main shutoff valve fall in plumbing scope splits?
It typically sits at the service entrance, marking the line between site/utility work and interior plumbing. On new construction the site or utility contractor may bring service to the valve, while the plumbing sub takes it from there. Confirm this boundary in the scope sheet so tap fees, meters, and backflow devices are not missed.
What related components should be estimated near the main shutoff?
Depending on the project, include the water meter or meter pit, backflow prevention assembly, pressure-reducing valve, isolation valves, and required signage or labeling. Local jurisdictions and the spec often dictate specific assemblies, so reviewing utility requirements and addenda prevents undersizing the line item or omitting a code-mandated device.
Does the main shutoff valve location affect a renovation bid?
Yes. If the valve is buried, hard to reach, or serves occupied areas, the estimator must price phased shutdowns, temporary water, and after-hours work to maintain service. Accessibility issues drive labor and coordination cost on occupied-building renovations and should be captured during the site walk, not assumed.
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