Verify the inputs
Measure or document each input. If a value is only an estimate, record its source and test a conservative alternative.
Wastewater/ CALCULATOR
Gravity drain fall
Convert pipe length and slope into vertical fall and a downstream invert depth.
FROM ESTIMATE TO ACTION
Use the result, not just the number.
Keep the calculation traceable
Save the input link or copied result together with the date, units and assumptions. A number without its inputs cannot be checked later.
Confirm the decision
Compare the estimate with the related guide, current product data and requirements that apply at your location before buying or building.
Inputs to verify
- Horizontal pipe length (m)
- Use horizontal plan length, not the sloped pipe length.
- Design slope (%)
- Confirm the required slope for the pipe and local rules.
- Upstream invert depth (m)
- Vertical depth from the chosen datum to the inside bottom of the pipe.