Leak Flow Estimate Calculator

• Orifice-based: Q = Cd × A × √(2ΔP / ρ)
• Measured collection: Q = Volume / Time

1. Choose Measured collection if you can catch water safely.
2. If using Orifice-based, enter pressure near the leak.
3. Select a shape and measure the opening dimensions carefully.
4. Set runtime and days to match your irrigation schedule.
5. Press Estimate Leak Flow to view results above.
6. Use Download CSV or Download PDF for records.

Why leak flow matters in gardens

Small leaks can waste more water than a whole planting bed needs. In drip and micro‑spray systems, a pinhole may run for every cycle, soaking one spot while starved zones dry out. Estimating flow helps you translate “a wet patch” into liters per minute, daily loss, and weekly cost, so repairs compete fairly with other maintenance tasks. Even modest leaks increase humidity, invite weeds, and can trigger fungal issues around sensitive stems too quickly.

Choosing an estimation method

Use measured collection when you can safely capture water. It automatically includes real pressure, hose kinks, and partial blockage. Use the orifice method when collection is impractical, such as buried laterals or leaks that atomize. Enter realistic gauge pressure near the leak, and treat the result as an upper‑bound when pressure fluctuates during watering.

Interpreting pressure, size, and Cd

The orifice equation links flow to opening area and the square root of pressure. Diameter errors matter because area rises with the square of size; a 2 mm hole carries about four times the area of a 1 mm hole. Cd represents edge shape and turbulence; sharp holes are often near 0.60–0.65, while irregular tears can behave differently. If the calculated flow looks extreme, re‑measure and consider switching to measured collection.

Turning flow into schedule losses

Once you have flow, the calculator multiplies by runtime to estimate daily volume, then scales by days per week. This converts continuous leakage into practical planning numbers: liters per day, gallons per week, and optional cost. If you run multiple zones, focus on the zone where the leak occurs, not the total controller runtime.

Prioritizing fixes and verifying improvements

Rank repairs by weekly loss, plant damage risk, and erosion potential. High flows near foundations, slopes, or mulched beds deserve urgent attention. After fixing, re‑run the calculator with the new measurement to confirm improvement, and keep the exported report as a baseline for future inspections.

1) Which method gives the most accurate leak flow?
Answer: Measured collection is usually best because it captures real pressure, restrictions, and spray breakup. Use the orifice method when you cannot collect water safely, and treat it as a reasonable estimate rather than an exact value.

2) What discharge coefficient should I enter for Cd?
Answer: For a sharp, clean hole in plastic tubing, start around 0.62. For rough tears, cracks, or jagged openings, results vary, so compare a few Cd values or switch to measured collection to reduce guesswork.

3) What if my pressure changes while the zone runs?
Answer: Use a pressure reading taken during irrigation near the leak point, not static supply pressure. If pressure is unknown or unstable, collect water for a timed interval and use the measured method.

4) How do I measure a tiny hole or slot?
Answer: Dry the tubing, mark the opening, and use a caliper if available. If not, compare against a drill bit shank, needle gauge, or a printed scale. For slots, measure both width and length.

5) How is water cost calculated in this tool?
Answer: The calculator converts your cost input to a per‑cubic‑meter rate, then multiplies by estimated daily and weekly volume. Choose the pricing basis that matches your bill, or leave cost at zero if unknown.

6) Can I use this for sprinklers or micro‑sprayers?
Answer: Yes, for small leaks at fittings, risers, and cracked bodies. For nozzle performance or intentional discharge, use manufacturer flow charts instead, because designed spray patterns do not behave like a simple leak.