# Plumbing Systems Design

## Water Supply Systems

### Pipe Sizing
| Fixture Units | Pipe Size |
|---------------|-----------|
| 1-2 FU | 1/2" |
| 3-5 FU | 3/4" |
| 6-10 FU | 1" |
| 11-20 FU | 1-1/4" |
| 21-40 FU | 1-1/2" |
| 41-75 FU | 2" |
| 76-150 FU | 2-1/2" |
| 151-300 FU | 3" |

### Fixture Unit Values
| Fixture | Hot | Cold | Total |
|---------|-----|------|-------|
| Lavatory | 0.5 | 0.5 | 1.0 |
| Kitchen sink | 1.0 | 1.0 | 1.5 |
| Bathtub | 1.0 | 1.0 | 2.0 |
| Shower | 1.0 | 1.0 | 2.0 |
| Water closet (tank) | - | 2.5 | 2.5 |
| Water closet (flush valve) | - | 6.0 | 6.0 |
| Urinal (flush valve) | - | 4.0 | 4.0 |
| Dishwasher | 1.0 | - | 1.5 |
| Clothes washer | 1.0 | 1.0 | 2.0 |

### Pipe Materials
| Material | Use | Temperature |
|----------|-----|-------------|
| Copper Type L | Domestic water | Up to 250°F |
| Copper Type M | Light duty | Up to 250°F |
| PEX | Residential | Up to 200°F |
| CPVC | Hot/cold | Up to 200°F |
| PVC | Cold only | Up to 140°F |
| Stainless | Commercial | High temp |

### Pressure Requirements
| Location | Pressure |
|----------|----------|
| Street main | 40-80 psi |
| Building supply | 45-60 psi |
| Fixture (min) | 8-20 psi |
| PRV required | > 80 psi |
| High-rise boost | Per floor height |

---

## Drainage Systems

### Drain Pipe Sizing
| DFU | Horizontal | Vertical |
|-----|------------|----------|
| 1-3 | 1-1/4" | 1-1/4" |
| 4-6 | 1-1/2" | 1-1/2" |
| 7-20 | 2" | 2" |
| 21-50 | 2-1/2" | 2-1/2" |
| 51-150 | 3" | 3" |
| 151-350 | 4" | 4" |
| 351-600 | 5" | 5" |
| 601-1000 | 6" | 6" |

### Drainage Fixture Units
| Fixture | DFU |
|---------|-----|
| Lavatory | 1 |
| Bathtub | 2 |
| Shower | 2 |
| Water closet | 4 |
| Kitchen sink | 2 |
| Dishwasher | 2 |
| Clothes washer | 3 |
| Floor drain | 2 |
| Urinal | 2-4 |

### Pipe Slopes
| Pipe Size | Minimum Slope |
|-----------|---------------|
| 2" and smaller | 1/4" per foot |
| 3" and larger | 1/8" per foot |
| Sewer | 1/8" per foot min |

### Pipe Materials (Drainage)
| Material | Use |
|----------|-----|
| Cast iron | Commercial, high-rise |
| PVC | Residential, commercial |
| ABS | Residential |
| HDPE | Below slab |
| Copper | DWV, specialty |

---

## Venting Systems

### Vent Sizing
| Fixture Connected | Vent Size |
|-------------------|-----------|
| 1-2 fixtures | 1-1/4" |
| 3-4 fixtures | 1-1/2" |
| 5-10 fixtures | 2" |
| 11+ fixtures | Size per code |

### Vent Types
| Type | Description |
|------|-------------|
| Individual | One fixture, one vent |
| Common | Multiple fixtures, shared vent |
| Wet vent | Drain serves as vent |
| Stack vent | Vent above highest connection |
| Air admittance valve | Mechanical one-way vent |

### Vent Requirements
| Requirement | Dimension |
|-------------|-----------|
| Max trap arm (1-1/4") | 2'-6" |
| Max trap arm (1-1/2") | 3'-6" |
| Max trap arm (2") | 5'-0" |
| Vent termination | 6" above roof |
| Distance from opening | 10' horizontal |

---

## Hot Water Systems

### Water Heater Types
| Type | Efficiency | Use |
|------|------------|-----|
| Storage tank (gas) | 0.60-0.70 | Residential |
| Storage tank (electric) | 0.90-0.95 | Residential |
| Tankless (gas) | 0.80-0.98 | On-demand |
| Heat pump | 2.0-3.5 COP | High efficiency |
| Indirect | 0.80+ | With boiler |
| Commercial | Varies | High volume |

### Sizing Guidelines
| Use | GPH at Rise |
|-----|-------------|
| Residential | 30-50 GPH/person |
| Office | 1-2 GPH/person |
| Restaurant | 1.5-3 GPH/seat |
| Hotel | 15-30 GPH/room |
| Hospital | 25-40 GPH/bed |

### Temperature Settings
| Application | Temperature |
|-------------|-------------|
| Domestic (residential) | 120°F |
| Dishwasher (sanitizing) | 140°F |
| Healthcare | 110°F at fixture |
| Storage (Legionella) | 140°F |
| Mixing valve | Required |

### Recirculation Systems
| Type | Description |
|------|-------------|
| Continuous | Always running |
| Timer-based | Scheduled |
| Demand (button) | User activated |
| Demand (sensor) | Automatic |
| Under-sink | Point-of-use |

---

## Fixtures

### Water Closets
| Type | Water Use | Application |
|------|-----------|-------------|
| Standard (tank) | 1.6 gpf | Residential |
| High-efficiency | 1.28 gpf | Commercial, green |
| Dual-flush | 1.1/1.6 gpf | Efficiency |
| Flush valve | 1.6 gpf | Commercial |
| Pressure-assist | 1.0-1.6 gpf | High performance |

### Lavatories
| Type | Use |
|------|-----|
| Drop-in | Countertop |
| Undermount | Countertop |
| Vessel | Countertop |
| Wall-hung | ADA, commercial |
| Pedestal | Residential |

### Faucet Flow Rates
| Fixture | Standard | Low-flow |
|---------|----------|----------|
| Lavatory | 2.2 gpm | 1.5 gpm |
| Kitchen | 2.2 gpm | 1.8 gpm |
| Showerhead | 2.5 gpm | 2.0 gpm |
| Pre-rinse spray | 1.6 gpm | 1.28 gpm |

### Fixture Rough-In
| Fixture | From Wall | From Floor |
|---------|-----------|------------|
| Water closet | 12" (10", 14" options) | - |
| Lavatory | Varies | 31" drain, 19" supply |
| Bathtub | Per fixture | 14" drain |
| Shower | Per fixture | 2" above floor |

---

## Commercial Systems

### Grease Interceptors
| Size | Flow Rate | Capacity |
|------|-----------|----------|
| Small | 10-15 gpm | 30-50 gal |
| Medium | 20-35 gpm | 100-200 gal |
| Large | 50-100 gpm | 500-2000 gal |

### Sizing Formula
```
Size = Flow Rate × Retention Time × Storage Factor
Typical: 2 lbs grease/meal served
```

### Backflow Prevention
| Device | Hazard Level | Use |
|--------|--------------|-----|
| Air gap | High | Most effective |
| RPZ | High | Commercial |
| Double check | Medium | Fire, irrigation |
| PVB | Low | Irrigation |
| AVB | Low | Hose bibb |

---

## Medical Gas

### Gas Types
| Gas | Symbol | Color |
|-----|--------|-------|
| Oxygen | O2 | Green |
| Medical air | MA | Yellow |
| Vacuum | VAC | White |
| Nitrogen | N2 | Black |
| Nitrous oxide | N2O | Blue |
| Carbon dioxide | CO2 | Gray |

### Outlet Requirements
| Room Type | O2 | VAC | MA |
|-----------|-----|-----|-----|
| Patient room | 1-2 | 1-2 | 0-1 |
| ICU | 2-3 | 2-3 | 2 |
| OR | 2-4 | 2-4 | 2-4 |
| Recovery | 1-2 | 1-2 | 1 |

---

## Fire Protection

### Sprinkler Types
| Type | Temperature | Color |
|------|-------------|-------|
| Ordinary | 135-170°F | Uncolored/black |
| Intermediate | 175-225°F | White |
| High | 250-300°F | Blue |
| Extra high | 325-375°F | Red |
| Very extra high | 400-475°F | Green |

### Coverage Areas
| Hazard | Max Coverage |
|--------|--------------|
| Light hazard | 225 SF |
| Ordinary Group 1 | 130 SF |
| Ordinary Group 2 | 130 SF |
| Extra hazard | 90-100 SF |

### Standpipe Classes
| Class | Use | Hose |
|-------|-----|------|
| I | Fire dept | 2-1/2" |
| II | Occupants | 1-1/2" |
| III | Both | Both |

---

## Storm Drainage

### Roof Drain Sizing
| Drain Size | Roof Area (SF) |
|------------|----------------|
| 2" | 1,600 |
| 3" | 3,600 |
| 4" | 6,680 |
| 5" | 11,500 |
| 6" | 18,400 |

Based on 4" per hour rainfall rate.

### Secondary Drainage
| Requirement | Description |
|-------------|-------------|
| Overflow | Required when parapet |
| Size | Equal to primary |
| Location | 2" above primary |
| Flow path | Independent |

### Area Drains
| Location | Size |
|----------|------|
| Parking | 4"-6" |
| Plaza | 4"-6" |
| Courtyard | 3"-4" |
| Planter | 2"-3" |

---

## Accessibility

### ADA Fixture Requirements
| Feature | Requirement |
|---------|-------------|
| Lavatory height | 34" max AFF |
| Knee clearance | 27" min |
| Clear floor | 30" × 48" |
| Pipe protection | Insulated |
| Controls | Lever or sensor |

### Toilet Clearances
| Feature | Dimension |
|---------|-----------|
| Centerline | 16"-18" from side wall |
| Clear floor | 60" × 59" min |
| Grab bars | Side (42") + rear (36") |
| Flush control | Open side |
| Seat height | 17"-19" |

---

## Sustainability

### Water-Efficient Fixtures
| Fixture | Baseline | Efficient |
|---------|----------|-----------|
| Water closet | 1.6 gpf | 1.28 gpf |
| Urinal | 1.0 gpf | 0.5 gpf or less |
| Lavatory | 2.2 gpm | 0.5 gpm |
| Showerhead | 2.5 gpm | 1.5 gpm |
| Kitchen faucet | 2.2 gpm | 1.5 gpm |

### Rainwater Harvesting
| Use | Treatment |
|-----|-----------|
| Irrigation | Filtration |
| Toilet flushing | Filtration + disinfection |
| Cooling tower | Filtration |
| Potable | Full treatment |

### Graywater Reuse
| Source | Use |
|--------|-----|
| Lavatory | Toilet flushing |
| Shower | Irrigation |
| Laundry | Irrigation |
| Not allowed | Kitchen, dishwasher |
