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Water Storage Guide
Water Storage Basics
Water tanks should be sized to bridge the gap between supply and demand. In the Caribbean, intermittent municipal supply (NWC in Jamaica, WASA in Trinidad) makes adequate storage essential. A minimum of 3 days supply is recommended; 5–7 days is standard for areas with unreliable service.
Rainwater Harvesting in the Caribbean
Caribbean rainfall is highly seasonal. The wet season (June–November) delivers approximately 65% of annual rainfall, while the dry season (December–May) provides only 35%. Effective rainwater harvesting requires a tank large enough to store wet season surplus for dry season use. Roof material, guttering condition, and first flush diversion all affect collection efficiency.
Tank Material Comparison
Material
Pros
Cons
Polyethylene
Lightweight, affordable, UV-resistant
Limited sizes, shorter lifespan
Concrete
Durable, any size, keeps water cool
Heavy, expensive, may crack
Steel
Strong, large capacities
Corrosion risk, expensive
Fiberglass
Corrosion-free, lightweight
Expensive, UV degradation
Pump Sizing Basics
Pump size depends on total dynamic head (elevation + friction losses) and desired flow rate. Friction losses are estimated at approximately 5% of elevation head for typical residential piping. Pump efficiency is typically 60% for small centrifugal pumps. Standard pump sizes: 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, and 5.0 HP.
Caribbean Water Supply Context
Many Caribbean islands face chronic water supply challenges. Jamaica's NWC (National Water Commission) provides piped water to approximately 70% of the population, but supply is often intermittent — sometimes as little as 2–3 days per week in some areas. Trinidad's WASA faces similar challenges. Private water storage is not optional but essential for continuity of supply. Rainwater harvesting supplements municipal supply and reduces dependence on trucked water during droughts.
Disclaimer: This calculator provides estimates for preliminary tank sizing. Actual requirements depend on site-specific conditions including local water supply reliability, rainfall patterns, and plumbing configuration. Always consult a qualified plumbing engineer for detailed system design.
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