Rainwater planning

Rainwater harvesting guides

Practical guides to measuring roofs, choosing coefficients, tanks, filters, overflow and maintenance.

How rainfall, horizontal roof area, runoff coefficient and system efficiency determine yield.

Why annual rainfall totals are not enough and how a monthly tank balance reveals overflow, shortage and useful capacity.

How roof material, slope, roughness, first flush and system losses affect the amount of water reaching the tank.

First flush reduces pollutant entry, but its volume should reflect roof size and required water quality.

A check plan for baskets, screens, sediment, pump, tank and overflow without claiming potable water.

How to compare design flow with manufacturer ratings and why the calculator does not replace drainage design.

Oversized or undersized tanks, missing overflow, wrong roof area, poor filtration and unrealistic demand assumptions.

What to consider for seasonal systems, frost-exposed pipes, tanks and pumps that are used only during warmer months.