# Plumbing & Pipe Flow Calc

Pipe volume, flow velocity, Hazen-Williams pressure loss, pipe sizing by velocity, thermal expansion, drain slope, tank fill time and bucket flow tests.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://plumbing-calc.x402tookit.com/openapi.json
- x402 manifest: https://plumbing-calc.x402tookit.com/.well-known/x402
- Catalog (free): https://plumbing-calc.x402tookit.com/catalog
- Health (free): https://plumbing-calc.x402tookit.com/health
- Uptime (free): https://plumbing-calc.x402tookit.com/uptime

## Endpoints (8)

### GET /bucket-test — $0.02
Flow rate in gpm and litres per minute from a bucket test: container volume and seconds to fill, with a daily-use estimate.
Params: volume: number, unit?: string, seconds: number, pressurePsi?: number
Example: https://plumbing-calc.x402tookit.com/bucket-test?volume=5&unit=gal&seconds=30

### GET /drain-slope — $0.02
Fall needed for a drain run at a given slope in inches per foot, or the slope of a measured fall, with typical code minimums.
Params: runFeet: number, inchesPerFoot?: number, fallInches?: number, pipeDiameterInches?: number
Example: https://plumbing-calc.x402tookit.com/drain-slope?runFeet=20&inchesPerFoot=0.25&pipeDiameterInches=2

### GET /flow-velocity — $0.02
Water velocity in feet per second from flow in gpm and pipe size, or the flow a pipe carries at a chosen velocity.
Params: nominalSize?: string, material?: string, insideDiameterInches?: number, flowGpm?: number, velocityFps?: number
Example: https://plumbing-calc.x402tookit.com/flow-velocity?nominalSize=3%2F4&material=pvc-40&flowGpm=5

### GET /pipe-size — $0.02
Smallest standard copper Type L or PVC Schedule 40 pipe that keeps water under a maximum velocity at your flow rate.
Params: flowGpm: number, material?: string, maxVelocityFps?: number
Example: https://plumbing-calc.x402tookit.com/pipe-size?flowGpm=10&material=copper-l&maxVelocityFps=5

### GET /pipe-volume — $0.02
Water held in a run of pipe in gallons and litres per foot and in total, from nominal size or inside diameter.
Params: nominalSize?: string, material?: string, insideDiameterInches?: number, lengthFeet: number
Example: https://plumbing-calc.x402tookit.com/pipe-volume?nominalSize=3%2F4&material=copper-l&lengthFeet=100

### GET /pressure-loss — $0.02
Friction pressure loss in psi (and feet of head) over a pipe run by the Hazen-Williams formula, from flow, size and C factor.
Params: nominalSize?: string, material?: string, insideDiameterInches?: number, flowGpm: number, lengthFeet: number, cFactor?: number
Example: https://plumbing-calc.x402tookit.com/pressure-loss?nominalSize=3%2F4&material=copper-l&flowGpm=10&lengthFeet=100

### GET /tank-fill-time — $0.02
Time to fill or drain a tank from its volume or round tank size and flow in gpm, with an optional outflow.
Params: volumeGallons?: number, volumeLiters?: number, tankDiameterInches?: number, waterDepthInches?: number, inflowGpm: number, outflowGpm?: number
Example: https://plumbing-calc.x402tookit.com/tank-fill-time?volumeGallons=50&inflowGpm=5

### GET /thermal-expansion — $0.02
How much a pipe run lengthens or shortens with temperature for copper, steel, PVC, CPVC, PEX or ABS, in inches and mm.
Params: material: string, lengthFeet: number, fromF: number, toF: number, coefficientPerF?: number
Example: https://plumbing-calc.x402tookit.com/thermal-expansion?material=copper&lengthFeet=100&fromF=50&toF=120

## Terms

Plumbing arithmetic computed locally from the numbers given, using standard hydraulic formulas and published pipe dimensions, provided as is. These are planning estimates: real systems also have fittings, valves, elevation, water temperature and local plumbing codes that govern what is permitted. Not a code-compliance check and not a substitute for a licensed plumber or engineer.