# Sovereignty Module: Catch the Rain

## Complete Primitive Water Collection and Rain Harvesting: From Cloud to Cistern

Rainwater harvesting provides a reliable, clean water source independent of wells or streams. This campaign covers collection surfaces, storage systems, filtration, and calculation of water yield.

### Chapter 1: Collection Surfaces

| Surface | Collection Efficiency | Contamination Risk | Cost | Durability | Area Needed |
|---|---|---|---|---|---|
| Metal roof (galvanized) | 90-95% | Low | Moderate | Excellent | Standard roof |
| Metal roof (painted) | 85-90% | Low-moderate | Moderate | Very good | Standard roof |
| Tile roof | 80-90% | Low | High | Excellent | Standard roof |
| Asphalt shingle | 75-85% | Moderate (chemicals) | Low | Good | Standard roof |
| Thatch roof | 60-70% | Moderate (organic) | Very low | Moderate | Standard roof |
| Concrete/stone | 80-90% | Low | Moderate | Excellent | Ground catchment |
| Plastic sheeting | 90-95% | Very low | Very low | Low (UV damage) | Any size |
| Rock outcrop | 70-85% | Low | Free | Permanent | Natural |

Water yield calculation: 1) Measure roof area in square feet. 2) Multiply by annual rainfall in inches. 3) Multiply by 0.623 (converts to gallons). 4) Multiply by collection efficiency (0.80-0.95). 5) Example: 1,000 sq ft roof x 40 inches rain x 0.623 x 0.90 = 22,428 gallons per year. 6) One inch of rain on 1,000 sq ft = approximately 560 gallons. 7) This is often more water than a family needs. 8) Key: adequate storage to capture wet-season surplus for dry-season use.

### Chapter 2: Gutter and Conveyance

| Component | Material | Function | Sizing |
|---|---|---|---|
| Gutters | Metal, PVC, bamboo, wood | Collect water from roof edge | 5-6 inch for standard roof |
| Downspouts | Metal, PVC, bamboo | Carry water from gutter to storage | 3-4 inch diameter |
| First flush diverter | PVC pipe with valve | Diverts first dirty water | 1 gallon per 100 sq ft roof |
| Leaf screen | Wire mesh, screen | Prevents debris entry | Cover all gutter openings |
| Settling tank | Barrel or tank | Allows sediment to settle | 50-100 gallons |
| Overflow | Pipe from tank | Prevents tank overflow damage | Same size as downspout |

First flush diverter: 1) First rain washes dust, bird droppings, and debris off roof. 2) This "first flush" is the dirtiest water. 3) Divert first 1 gallon per 100 sq ft of roof area. 4) Simple design: vertical pipe below downspout with ball valve at bottom. 5) Pipe fills with dirty water first (ball floats up, sealing pipe). 6) Clean water then flows to storage tank. 7) Drain first flush pipe after each rain event. 8) Dramatically improves water quality with minimal cost.

### Chapter 3: Storage Systems

| Storage Type | Capacity | Cost | Durability | Material | Best For |
|---|---|---|---|---|---|
| Rain barrel | 55-100 gallons | Very low | Good | Plastic (HDPE) | Small gardens |
| IBC tote | 275 gallons | Low | Good | Plastic/metal cage | Moderate use |
| Polyethylene tank | 500-10,000 gallons | Moderate | Very good | Plastic | Household supply |
| Ferrocement cistern | 500-10,000+ gallons | Low (DIY) | Excellent | Cement, wire mesh | Large-scale, permanent |
| Underground cistern | 1,000-50,000+ gallons | Moderate-high | Excellent | Concrete, fiberglass | Large-scale, hidden |
| Stone/brick cistern | 500-5,000 gallons | Moderate | Excellent | Masonry | Permanent, traditional |

### Chapter 4: Water Quality

| Contaminant | Source | Treatment | Prevention |
|---|---|---|---|
| Bird droppings | Roof surface | First flush diverter, filtration | Screen gutters |
| Dust/pollen | Atmosphere | Settling, filtration | First flush diverter |
| Leaf debris | Trees | Gutter screens, filtration | Trim overhanging branches |
| Mosquito larvae | Standing water | Sealed tanks, screen vents | No open water surfaces |
| Algae | Light + nutrients | Opaque tanks, dark storage | Block all light |
| Bacteria | Various | UV treatment, chlorination, filtration | Sealed system, regular cleaning |

### Chapter 5: System Design

| Household Size | Daily Need | Monthly Need | Minimum Storage | Recommended Storage |
|---|---|---|---|---|
| 1 person | 5-10 gallons | 150-300 gallons | 500 gallons | 1,000+ gallons |
| 2 people | 10-20 gallons | 300-600 gallons | 1,000 gallons | 2,500+ gallons |
| 4 people | 20-40 gallons | 600-1,200 gallons | 2,500 gallons | 5,000+ gallons |
| Small farm | 50-100 gallons | 1,500-3,000 gallons | 5,000 gallons | 10,000+ gallons |

### Reference Card

1. One inch of rain on 1,000 square feet equals 560 gallons (most roofs collect far more water than people realize; calculate your yield). 2. First flush is the dirtiest (the first rain washes contaminants off the roof; always divert the first flush away from your storage). 3. Opaque tanks prevent algae (light promotes algae growth; use dark or opaque storage containers and block all light). 4. Screen everything (mosquitoes breed in standing water; screen all openings, vents, and overflows to prevent mosquito entry). 5. Gravity is free pressure (elevate your tank and gravity provides water pressure; 1 foot of elevation equals 0.43 PSI). 6. Size storage for dry season (calculate how many days between rain events in your driest season; size your tank to bridge that gap). 7. Ferrocement is the cheapest large tank (a DIY ferrocement cistern costs a fraction of a commercial tank and lasts decades). 8. Rainwater is soft water (rainwater has no minerals, making it excellent for washing, gardening, and with treatment, drinking).