Estimate one rain event and available tank space, assess a suitable irrigation use, and plan storage, delivery and inspection records.
Specify the intended irrigation use and check local collection, plumbing and site rules. Assess roof and storage materials and ask the health or agricultural authority what testing or treatment that use requires. Keep harvested water separate from the drinking-water system.
Enter catchment area, one event’s rain depth, routed percentage, first-flush allowance, tank capacity and starting storage. Inspect gross, inflow, retained and overflow quantities separately. Repeat for plausible smaller and larger events.
Select a suitable covered tank and a base designed for its filled load. Keep inlets screened and access secured, provide maintenance access and route overflow away from structures and neighboring property as locally permitted. Review how the tank will be drained or winterized.
Record intended zones, component operating ranges and the lowest usable tank level. Have the pump or gravity arrangement checked against actual pressure and flow requirements. Use nominal emitter demand and a timed delivery trial to check the completed system.
Record rainfall, starting and ending tank levels, irrigation withdrawals, overflow and any mains-water backup separately. Inspect screens, first-flush devices and water condition. Compare the record across wet and dry periods before changing storage or expecting reliable supply.
Keep the intended use, local requirements and water-quality questions. · Record the tank/base specification, secured access and overflow destination. · Keep the continuous tank-use and maintenance record beyond the one-event calculator.
Calculate event inflow, free storage, retention and overflow using explicit assumptions. · Reproduce individual rain-event storage changes using observed starting levels.
Calculate nominal emitter demand and measure sampled delivery; the tool does not size a pump or gravity head.
Loading your checklist…
Rainwater can carry germs and chemicals. Keep it separate from drinking-water pipes and obtain use-specific local advice. First flush and screens help system management but do not certify safe water.
Available space equals capacity minus starting storage. Retained inflow is limited by that space; excess is overflow. Daily consumption between storms and seasonal rainfall patterns require a longer storage record.
Drip equipment requires appropriate flow, filtration and operating pressure. Tank capacity does not select pipes, regulators or pumps.
An almost full tank has much less usable event capacity than an empty tank.
Rainfall totals alone do not show whether water will be available when irrigation is needed.