Learn Drainage Design
Master the fundamentals of stormwater drainage design with our comprehensive guides. Follow a structured pathway or browse individual articles by topic.
Whether you're a homeowner dealing with a wet basement, a contractor designing your first stormwater system, or a professional engineer solving complex drainage challenges, this comprehensive learning resource has you covered. We've organized 38 free guides covering everything from basic hydrology principles to advanced infrastructure design methods.
Drainage design connects hydrology, hydraulics, and civil engineering. The same fundamental principles apply whether you're designing a French drain for a residential lot or a storm sewer system for a highway. Our guides take you through the essential concepts, calculation methods, and practical applications used in the field today.
Each guide includes worked examples, design equations, equipment specifications, and direct links to our free professional-grade calculators. No account required — just open, learn, and apply.
Who Should Learn Here?
- Homeowners: Understand residential drainage problems — wet basements, water pooling, foundation damage — and explore solutions from French drains to grading improvements.
- Contractors: Learn sizing methods, material selection, and cost estimation for drainage work. Understand the calculations behind your designs and communicate better with engineers.
- Engineers: Reference guides for design standards, advanced methods like SCS curve numbers and HEC-22 inlet design, and proven approaches to complex site drainage challenges.
Start With These Fundamentals
New to drainage design? These three articles build the foundational knowledge needed for everything else:
- Drainage Design 101 — Learn basic hydrology, runoff, and how drainage systems work.
- Manning's Equation Explained — Master the most important calculation in drainage engineering.
- Rational Method Explained — Calculate peak flow for your site using the Rational Method.
What You'll Learn
Our learning resources are organized into four key areas:
- Fundamentals: Core hydrology and drainage principles
- Methods: Calculation techniques (Manning's equation, Rational Method, SCS Curve Numbers, etc.)
- Applications: Practical design guides for specific drainage scenarios
- Reference: Tables, selection guides, and technical specifications
Learning Pathways
Follow a structured curriculum to build your knowledge step by step. Your progress is saved automatically.
Drainage Design 101
Start here — learn the fundamentals of how water moves and how to design drainage systems.
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1. How Drainage Works
8 min readUnderstand why water collects and how drainage systems move it.
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2. Understanding Runoff
6 min readLearn how rainfall becomes runoff and what affects how much you get.
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3. The Rational Method
10 min readThe most common way to calculate how much water you need to handle.
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5. Choosing a Solution
7 min readFrench drains, rain gardens, catch basins — which one fits your situation?
Stormwater Management
Learn how to manage stormwater with modern green infrastructure approaches.
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1. Curve Number Method
10 min readA more detailed way to estimate runoff for larger or more complex sites.
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2. Time of Concentration
8 min readHow long it takes water to travel across your site — critical for sizing.
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3. Reading Hydrographs
6 min readUnderstanding flow over time, not just peak values.
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All Articles
Fundamentals
Start here to learn the basics of drainage design and hydrology.
Drainage Design 101
Learn the fundamentals of stormwater drainage design, from basic hydrology concepts to practical engineering applications.
Understanding Hydrographs
Learn how to interpret hydrographs, understand their components, and apply hydrograph analysis to stormwater design.
Methods
Detailed explanations of calculation methods used in drainage engineering.
Rational Method Explained
Master the Rational Method for peak flow estimation. Learn the theory, equation derivation, runoff coefficients, and practical applications.
SCS Curve Number Method
Comprehensive guide to the SCS Curve Number method for runoff estimation, including CN selection and calculation procedures.
Manning's Equation Explained
Master Manning's Equation for open channel and pipe flow calculations. Learn the theory, n-value selection, and applications.
Time of Concentration
Comprehensive guide to calculating time of concentration for drainage design with multiple methods and worked examples.
Selecting the Right Design Storm
Learn how to select appropriate design storm return periods for different drainage applications. Understand risk, consequences, and regulatory requirements.
Applications
Practical guides for specific drainage design scenarios.
Channel Design
Design open channels and ditches for stormwater conveyance using Manning's Equation and proper channel geometry.
Subsurface Drainage
French drains, dry wells, and foundation drains explained. Learn when and how to use subsurface drainage solutions.
Roof Drainage
Gutters, downspouts, and roof drain sizing. Understand how to manage water from your roof.
Flat Roof Drainage
Design drainage systems for flat and low-slope roofs, including scupper sizing and secondary overflow.
Storm Drain Systems
Design storm drain networks from inlets to outfall. Learn pipe sizing, energy grade line analysis, and system layout.
Roadway Drainage
Design drainage systems for roads and highways, including inlet spacing, cross drainage, and longitudinal drainage.
Open Channel Flow
Understand the principles of open channel flow including uniform flow, critical flow, and gradually varied flow.
Open Channel Hydraulics
Advanced open channel hydraulics concepts including specific energy, hydraulic jumps, and flow transitions.
Storm Drainage Design
Complete guide to storm drainage system design from watershed analysis through final pipe sizing.
Residential Drainage Basics
Understand residential drainage problems and solutions. Learn about grading, French drains, sump pumps, downspout management, and when to call a professional.
Generate Client Proposals
How drainage contractors use free calculators to build data-backed proposals — with a proposal checklist, sample scope items, and worked cost line items.
Green Infrastructure Basics
Introduction to green infrastructure for stormwater management. Learn about rain gardens, bioswales, permeable pavement, green roofs, and their benefits for communities.
Reference
Comprehensive tables and selection guides for design parameters.
Runoff Coefficients Guide
Comprehensive guide to selecting runoff coefficients for the Rational Method, including tables and composite calculations.
Hydrologic Soil Groups
Learn how to identify and use hydrologic soil groups (A, B, C, D) for drainage calculations with NRCS Web Soil Survey guidance.
Manning's n Selection Guide
Comprehensive guide to selecting Manning's roughness coefficient for pipes, channels, and natural streams.
Glossary
Searchable glossary of drainage engineering terms with definitions, related calculators, and cross-references.
Ready to Apply What You've Learned?
Put theory into practice with our free professional-grade drainage calculators.
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