"Landscape Water Budget: MAWA vs. ETWU" is lesson 1 of 7 in the Landscaping (C-27) Learning Hub. It opens with "What the Water Budget Is For" and works through 5 short steps, then a worked example you can check yourself against.
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Steps in this lesson
What the Water Budget Is For
The Ceiling: MAWA
The Estimate: EWU for Each Hydrozone
Why Drip and Low-Water Plants Win on Paper
Compare, Then Fix the Biggest Line
The worked example in the course applies this lesson to a realistic job in 7 steps, starting with "ETAF for each hydrozone".
What you'll be able to do
Explain the main idea of "Landscape Water Budget: MAWA vs. ETWU" in plain language you can use on the exam.
Apply this step with confidence: "The Estimate: EWU for Each Hydrozone".
Apply this step with confidence: "Why Drip and Low-Water Plants Win on Paper".
Apply this step with confidence: "Compare, Then Fix the Biggest Line".
Test yourself on the worked example and the quick-check quiz inside the classroom.
The diagram for this lesson, exactly as it appears in the Learning Hub.
The first steps of this lesson
Step 1: What the Water Budget Is For
California's Model Water Efficient Landscape Ordinance (MWELO, 23 CCR Division 2, Chapter 2.7) applies to new landscapes of 500 sq ft or more that need a building or landscape permit, plan check or design review, and to rehabilitated landscapes of 2,500 sq ft or more (MWELO Sec. 490.1(a)(1)-(2)). The designer must complete the Water Efficient Landscape Worksheet and show that the Estimated Total Water Use (ETWU) of the design does not exceed the Maximum Applied Water Allowance (MAWA) (MWELO Sec. 492.4(a)). Projects of 2,500 sq ft or less may instead follow the prescriptive measures in Appendix D (Sec. 490.1(c)). As the installer you will be handed a design built on this math, and you must not change plants, zones or emitters in a way that breaks it.
Step 2: The Ceiling: MAWA
MAWA = ETo x 0.62 x [ETAF x RLA + 1.0 x SLA] (MWELO Sec. 490.2(50) and Appendix A worksheet). ETo is the annual reference evapotranspiration, in inches, for the nearest city in the Appendix C table; 0.62 converts acre-inches per acre per year into gallons per square foot per year (Sec. 490.2(11)). ETAF may not exceed 0.55 for residential regular landscape area (RLA) or 0.45 for non-residential RLA (Sec. 490.2(26)). A Special Landscape Area (SLA) - ground permanently and solely dedicated to edible plants, recreation areas, or recycled-water areas (Sec. 490.2(79)) - is allowed an ETAF of 1.0, and RLA = LA - SLA.
The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.
Independent exam preparation. Contractors Classroom is not affiliated with the Contractors State License Board, and no course can guarantee a passing result.
