Estimate drain time for beds, pots, tanks, and pits. Review graphs, tables, and export files. Understand outlet flow, soak rate, and emptying performance clearly.
| Case | Volume (L) | Footprint (m²) | Outlet Diameter (mm) | Outlets | Infiltration (mm/hr) | Drain Time |
|---|---|---|---|---|---|---|
| Raised bed after heavy rain | 120.00 | 2.00 | 20.00 | 2 | 14.00 | 7.97 minutes |
| Planter trough | 60.00 | 0.90 | 15.00 | 1 | 10.00 | 15.33 minutes |
| Drain pit beside garden path | 300.00 | 3.00 | 32.00 | 2 | 22.00 | 5.50 minutes |
This calculator estimates how long standing water needs to leave a garden bed, container, trough, or pit. It combines outlet drainage and soil infiltration into one effective discharge rate.
1. Water volume conversion
V = Volume in liters / 1000
2. Footprint area
Afootprint = Length × Width
3. Initial water depth
h = V / Afootprint
4. Total outlet area
Aoutlet = n × π × d² / 4
5. Outlet discharge
Qoutlet = Cd × Aoutlet × √(2ghavg) × Efficiency
6. Soil infiltration flow
Qsoil = (Infiltration rate × Soak area) / 3600 × Efficiency
7. Total drain time
t = V / (Qoutlet + Qsoil) × Safety factor
The graph uses the calculated effective rate to show estimated water remaining across the drainage period. This makes comparison easy when you test different outlet sizes, soil conditions, or safety assumptions.
Enter the stored water volume that must drain from your garden space. Add the surface length and width so the calculator can estimate average water depth.
Next, enter the outlet diameter, number of outlets, and discharge coefficient. These values control how quickly water leaves through holes, pipes, or drains.
Then enter soil infiltration rate and soak area. This captures how much water disappears through the soil around the bed, pit, or planter base.
Use the efficiency factor to account for partial clogging, debris, roots, or imperfect conditions. Use the safety factor when you want a more conservative estimate.
Press calculate. The page will show drain time, depth, outlet flow, infiltration flow, total effective rate, a graph, and export buttons above the form.
It is the estimated time needed for stored water to leave a garden space through outlets and soil infiltration under the conditions you entered.
They help estimate average water depth. Depth affects outlet discharge, so footprint size changes the predicted emptying time.
It adjusts ideal outlet flow to a realistic value. Losses from shape, friction, and entrance effects make actual flow lower than theoretical flow.
Yes. Set outlet diameter or outlet count to zero, then enter infiltration rate and soak area. The result will reflect infiltration-driven drainage only.
It reduces both outlet and soil flow to reflect clogging, sediment, roots, screens, or other conditions that limit real drainage performance.
It stretches the final time estimate. This is useful when you want a conservative planning value for uncertain field conditions.
Yes. It works for containers, beds, troughs, barrels, and shallow pits, as long as the entered dimensions and drainage assumptions are reasonable.
The calculator uses an effective average drainage rate for practical planning. That keeps the visual simple while still helping compare different scenarios.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.