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Darcy's Law Seepage Flow Rate Calculator

Compute groundwater seepage flow rate through soil using Darcy's Law.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Seepage flow rate

0.05 L/s

Check your inputs

Darcy's Law assumes laminar flow through a fully saturated, homogeneous, isotropic soil — it becomes less accurate in highly fractured rock, karst, or coarse gravel where flow may be turbulent.

Equivalent in m³/s
0 m³/s
Equivalent in m³/day
4.32 m³/day

With the figures above, the seepage flow rate comes to 0.05 L/s. Note that hydraulic conductivity (k, m/s) and hydraulic gradient (i) sit at the edge of the range this calculator was checked against, so treat the output as indicative rather than settled. The method behind this is well established, though site conditions and material batches will move it somewhat. This is calculated for United States and cites IRC 2024. Building in another market? Change the selector above so the units and code reference follow.

Add the equipment this sizes

This result is a specification — 0.05 L/s — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Darcy's Law: Q = k x i x A, where Q is flow rate, k is hydraulic conductivity, i is the hydraulic gradient, and A is the cross-sectional flow area

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Frequently asked questions

What does the hydraulic gradient represent physically?
It's the slope of the groundwater table (or piezometric surface) along the flow direction — steeper gradients drive faster seepage flow for the same soil permeability.
Why does this matter for dewatering or excavation?
It directly predicts how much water will flow into an excavation or through a soil mass — used to size pumps, sumps, and dewatering wells, and to assess seepage-related stability concerns like piping or heave.
Does Darcy's Law apply to all soil types equally?
It's most accurate for fine-to-medium granular soils and normally consolidated clays under laminar flow conditions — very coarse gravel or fractured rock can have turbulent flow where Darcy's Law becomes less accurate.