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Plumbingaka: water supplyaka: supply pipeaka: feed line

Supply Line

In Plain English

The water pipe that delivers hot or cold water from the main pipes to a specific fixture like a sink or toilet.

Definition

The pipe or tubing that delivers hot or cold water from the main distribution system to individual fixtures, appliances, and equipment. Supply lines include the main distribution piping, branch lines, and the short flexible tubes that connect shut-off valves to fixture faucets. They must be properly sized to maintain adequate flow and pressure at all fixtures.

Why It Matters in Bidding

Supply line sizing and material drive both the plumbing rough-in takeoff and the fixture connection count, so misreading the riser diagram or fixture schedule can leave a bid short on pipe, fittings, and labor hours. Pressure and flow requirements also dictate pipe diameter, which affects material cost and whether a booster pump or pressure-reducing valve belongs in scope.

Example

An estimator counts 42 fixtures off the plumbing plans and prices the branch and supply piping in copper as specified, then flags an addendum that switched the spec to PEX so the bid reflects the lower material cost.

Related Terms

Domestic WaterCopper PipingPEX TubingPressure Regulator

Frequently Asked Questions

Estimators trace the riser diagram and floor plans to measure linear footage by pipe size and material, count fittings and shut-off valves, and tally fixture connections from the fixture schedule. Each fixture typically needs hot and cold stops plus flexible connectors, so the count feeds both material and labor-unit pricing.
Significantly. Copper costs more in material and soldering labor than PEX or CPVC, and copper price volatility can swing a bid. The spec may dictate material by application, so estimators confirm allowable types, check addenda for substitutions, and price accordingly rather than assuming the cheapest option.
Typically the plumbing sub provides and connects the supply stops and flexible risers as part of fixture trim-out. Estimators should confirm whether owner-furnished or appliance-vendor fixtures include their own connectors to avoid double-counting or scope gaps at the rough-in versus finish phase.

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