Water Service Pipe Sizing

Size domestic water service and building distribution per NSPC 2021 (N.J.A.C. 5:23-3.15) Appendix B simplified method. Pressure budget, booster sizing, fixture supply branch table, residential water softener.
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Project Information (optional · click to expand)

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Firm

Remember firm info on this device (localStorage; never sent off your machine)

Project

Occupancy Type — Table 10.14.2A Column

Quick-Add Presets

Presets increment existing entries (they do not overwrite). Each click adds the listed fixtures to the Individual Fixtures table below — click twice for two units. Reset asks for confirmation, then clears every quantity and moves focus to the occupancy selector.

Bathroom Groups — Table 10.14.2A

1 Bathroom Group = 1 WC + up to 2 lavs + 1 tub OR 1 bath/shower combo OR 1 shower. Half-Bath = 1 WC + 1 lav. WSFU table switches automatically based on the dominant WC type entered below. Mixed WC types show all relevant tables side by side.

Bath group subtotal0.0 WSFU

Individual Fixtures — Table 10.14.2A

Fixture	Min Branch	WSFU	Qty

Individual fixture subtotal0.0 WSFU

Total Water Supply Fixture Units

Total WSFU (bath groups + individual)0.0 WSFU

Cold-side WSFU (§10.14.3.a: cold-only + 0.75 × dual)0.0

Hot-side WSFU (§10.14.3.a: 0.75 × dual only)0.0

Note 4 (Table 10.14.2A): Listed values are cold-water service load. For fixtures with both cold and hot connections, each side gets 3/4 of the total. Cold-only fixtures (WCs, urinals, hose bibbs, drinking fountains) contribute full WSFU to cold side and zero to hot side per the hc flag. Note 5: Round to nearest whole before Table 10.14.2B lookup.

Residential Notes

IRC-NJ Chapter 29 deferral: §P2901-P2903 and §P2905-P2913 all defer to N.J.A.C. 5:23-3.15 (NJ Plumbing Subcode adopting NSPC). Sizing for individual-dwelling-unit residential follows NSPC throughout.

Sprinkler carve-out (SPRINKLER_CARVEOUT, IRC-NJ §P2904.6): Sprinkler design flow is NOT added to plumbing fixture demand. This tool sizes domestic supply only; it does not size sprinkler supply. If §P2904 sprinklers are required, the sprinkler contractor designs that supply separately per NFPA 13D or the §P2904 prescriptive tables.

Service Entry (optional · click to expand · BFP & meter drive Pressure Budget loss)

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Curb valve, backflow preventer, meter, and sprinkler-service coordination per §10.5.3 / §10.12 / §B.9.5. BFP type+size and meter size drive the Meter Loss and BFP Loss values shown in Pressure Budget below. Either may be overridden in Pressure Budget with the inline "override" link.

Curb Valve (city side) — §10.12.1

Curb valve present (approved gate / ball / ground-key stopcock in curb box)

Curb valve size

Backflow Preventer — §10.5.3 / §10.12.2

BFP type

BFP size

Plumbing-plan tag (optional)

Water Meter — §B.9.5 (AWWA C700 displacement-type)

Meter size

Meter type

Service Entry Location

Entry location (free text)

Depth below grade (in.)

Sprinkler Service Coordination

Sprinkler service is a separate line (no domestic sharing)

Domestic and sprinkler share a DCDA at the service entry

Source note: BFP and meter loss values are typical-not-source defaults (per Build Protocol clause 8) marked with † until manufacturer / AWWA C700 source data is encoded. Override either value in Pressure Budget if your manufacturer data sheet differs.

Floors & Chases (optional · click to expand · v1.2-arch organizational primitives)

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Unit Types & Units (optional · click to expand · v1.2-arch repeatable rooms + common-area fixtures)

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Define repeatable Unit Types (e.g., "1BR Apt", "2BR Apt") with their fixture sets; place instances of those types onto floors. Each unit may override its base type's fixture quantities (e.g., +1 dishwasher). Common-Area Fixtures at the bottom hold site / shared-space fixtures not bound to any unit.

Unit Types library

Unit instances

Type: Floor:

Common-Area Fixtures (site / common-space fixtures not bound to any unit)

Heaters (optional · click to expand · v1.2-arch — auto-created from container flags + free-form)

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Heaters auto-created from container flags (Unit Type "Internal WH", Floor "WH on floor", Chase "WH in chase") appear in the upper list and cannot be moved or deleted from here — toggle the flag on the container itself. Free-form heaters (basement commons, custom service zones) live in the lower list and persist regardless of container toggles.

Free-form heaters

Pressure Budget

Available pressure at the most-distant governing fixture = street static − elevation rise − meter loss − BFP loss − PRV loss − piping losses. Governing required pressure is the max required flowing pressure across all entered fixtures (§10.14.2.a). Meter and BFP loss are computed from Service Entry above; click "override" beside either to enter a specific manufacturer value.

Street pressure (psi)

Elevation rise (ft)

Meter loss (psi) override

5(default)

BFP loss (psi) override

12(default)

PRV loss (psi)

Other (psi)

Pipe Materials & Developed Lengths

Simplified §B.7.3 method. Developed length = actual run + fitting allowance (typically actual × 1.5). Hot main is sized after the water heater. Velocity caps: 8 fps general (§10.14.1 / §B.6.2); 5 fps copper hot (§B.6.3(3)); 4 fps when aggressive water checkbox is enabled (§B.6.3(2)).

Service Line (Main to Building)

Material

Developed length (ft)

Cold Water Main (Building Distribution)

Material

Developed length (ft)

Hot Water Main (After Water Heater)

Material

Developed length (ft)

# Water heaters

Aggressive water / zero-hardness softened (caps copper velocity at 4 fps per §B.6.3(2)). Disabled for CPVC and PEX.

Results

Riser Diagram

Text Output Preview

Sizes domestic water service and building distribution per NJ UCC Plumbing Subcode 2021 (NSPC adoption N.J.A.C. 5:23-3.15) Appendix B simplified method §B.7.3 — copper Types K/L/M, CPVC SDR11, PEX SDR9. Includes pressure budget, booster pump and PRV triggers (§10.14.4 / §10.14.6), per-fixture governing pressure (§10.14.2.a), fixture supply branch table, residential water softener sizing (§10.19), and SVG/PNG/DXF riser diagram export. IRC-NJ Chapter 29 deferral handled per N.J.A.C. 5:23-3.15; §P2904 dwelling-unit sprinkler demand is NOT added to plumbing fixture demand (per §P2904.6) and this tool does not size sprinkler supply.

Outputs are calculation aids for design professionals; verify against currently adopted code and AHJ before submittal. The Uniform Pipe Friction Loss Method (§B.9.6) is deferred to a future release; the simplified §B.7.3 method covers the architectural-scale projects this tool targets. Green Stories LLC is a building design and consulting firm.