How to Use the Drainage Fall Calculator

A Drainage Fall Calculator determines the vertical drop (or "fall") in elevation needed over the length of a drainage pipe based on a specified slope percentage.

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What It Does:

In drainage and plumbing design, it's critical to maintain a consistent slope in pipes to ensure proper water flow. This calculator helps you determine how much vertical fall (in meters) is needed over a given length of pipe to meet slope requirements (expressed as a percentage).

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How to Use the Calculator:

1. Enter the total length of the pipe in meters.
2. Enter the slope or fall percentage (common values range from 1% to 4%).
3. Click “Calculate Fall” to get the result.

The output tells you the total fall in meters that the pipe should have from start to end.

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Example:

If your pipe length is 30 meters and your slope is 2%, the fall will be:

30 × 0.02 = 0.60 meters

This means one end of the pipe must be 0.6 meters lower than the other to maintain a 2% slope.

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Drainage Fall Calculator FAQ

Q1: What does "fall" mean in drainage?
A: "Fall" refers to the vertical drop in elevation along a pipe run, ensuring water flows by gravity.

Q2: What is a typical slope for drainage pipes?
A: Residential pipes commonly use 1%–2% slopes (i.e., 1–2 cm drop per meter of pipe).

Q3: Why is proper fall important?
A: Too little fall causes clogs; too much fall can cause water to flow too quickly, leaving solids behind.

Q4: Can I use feet or inches instead of meters?
A: This calculator is designed for metric units. To use imperial units, convert feet to meters (1 ft ≈ 0.3048 m).

Q5: Is this suitable for stormwater and sewage?
A: Yes. While requirements vary, the fall principle applies to both types of systems. Always consult local codes for specifics.