Methodology
We show our work.
Every number AuditFlow produces is traceable to an industry-standard formula. No black boxes. No proprietary magic. Just math you can verify.
Distribution Uniformity
How uniformly water is distributed across a zone. The industry-standard lower-quarter DU method, defined by the Irrigation Association.
DU = (Avg of Lower Quarter / Avg of All) × 100
Lower Quarter = lowest 25% of catch-can readings
Sort ascending, take first ceil(n ÷ 4) values
PR (in/hr) = (Avg Depth ÷ Run Min) × 60
Overall DU = mean of all zone-level DU values
Overall PR = mean of all zone-level rates
Grading
Based on the IA Landscape Irrigation Auditor handbook and ASABE/ICC 802-2014.
16 catch-can readings (in): 0.42, 0.38, 0.45, 0.31, 0.29, 0.44, 0.40, 0.36, 0.47, 0.33, 0.41, 0.28, 0.39, 0.43, 0.35, 0.37
Lower quarter count: ceil(16 ÷ 4) = 4
Lower quarter values (sorted): 0.28, 0.29, 0.31, 0.33 → avg = 0.3025
Overall avg: 6.08 ÷ 16 = 0.38
DU = 0.3025 ÷ 0.38 × 100 = 79.6% → Good
If run time = 15 min: PR = (0.38 ÷ 15) × 60 = 1.52 in/hr
System Health Scoring
Starts at 100. Deducts points per finding based on severity. Multiple instances multiply the deduction. Score floors at 0.
Score = 100 − Σ(Deduction × Qty)
for all unresolved findings, floored at 0
Grading
The 15/7/3 weighting reflects industry norms. A critical finding (e.g., mainline leak) causes significant waste, justifying a 5× multiplier over a minor issue. Quantity multiplier ensures 10 clogged heads score worse than 1.
CLCA Water Budget
California’s MWELO compliance. Two values: the Maximum Applied Water Allowance (MAWA) sets the ceiling, and Estimated Total Water Use (ETWU) is actual consumption. Compliant when ETWU ≤ MAWA.
MAWA (gal/yr) = ETo × 0.62 × LA × ETAF
ETo = Reference Evapotranspiration (in/yr)
LA = Landscape Area (sq ft)
ETAF = ET Adjustment Factor (0.7 default)
0.62 = conversion constant (in × sq ft → gal)
ETWU (gal/yr) = Σ[(ETo × PF × HA × 0.62) ÷ IE]
per hydrozone
PF = Plant Factor (WUCOLS) · HA = Hydrozone Area · IE = Irrigation Efficiency
Pass if ETWU ≤ MAWA
WUCOLS Plant Factors
| Plant Type | Low | Mod | High |
|---|---|---|---|
| Cool Turf | 0.6 | 0.8 | 1.0 |
| Warm Turf | 0.6 | 0.7 | 0.8 |
| Shrubs | 0.1 | 0.3 | 0.5 |
| Trees | 0.2 | 0.5 | 0.9 |
| Groundcover | 0.1 | 0.35 | 0.5 |
| Mixed | 0.2 | 0.4 | 0.6 |
Based on California MWELO (CCR Title 23, Div 2, Ch 2.7) and WUCOLS IV.
Property: 10,000 sq ft in Sacramento, CA · ETo = 54 in/yr
MAWA = 54 × 0.7 × 10,000 × 0.62 = 234,360 gal/yr
Zone 1: Cool Turf (High) — 4,000 sq ft, IE 0.75, PF 1.0 → 178,560 gal
Zone 2: Shrubs (Mod) — 3,500 sq ft, IE 0.81, PF 0.3 → 43,547 gal
Zone 3: Trees (Mod) — 2,500 sq ft, IE 0.81, PF 0.5 → 51,667 gal
ETWU = 273,774 gal/yr > 234,360 → Not compliant (17% over)
Metered Flow Budget
Project water consumption per zone from measured GPM and programmed runtimes. Aggregate to weekly, monthly, and annual totals with cost projections.
Gal/Cycle = GPM × (AM Min + PM Min)
Weekly = Gal/Cycle × Days/Week
Monthly = Weekly × 4.33
Annual = Weekly × 52
If CCF: Annual Cost = (Annual Gal ÷ 748) × Rate
If per-gal: Annual Cost = Annual Gal × Rate
748 gal = 1 CCF (AWWA standard)
Scenario Suggestions
| Condition | Scenario |
|---|---|
| Budget ≥ 90% | Survivability |
| Budget 70–89% | Water Saver |
| Arid (AZ, NV, NM, UT) | Water Saver |
| Semi-arid, Summer | Water Saver |
| Semi-arid, Winter | Survivability |
| Semi-arid, Spring/Fall | Full |
| Temperate, Winter | Survivability |
| Temperate, Growing | Full |
Cost methodology aligned with AWWA M22.
Water Savings Estimates
Every unresolved finding has a waste factor. Sum them up, convert to dollars. That’s what your client is losing — and what they’ll save.
Monthly Waste (gal) = Σ[Waste Factor × Qty]
Annual Waste = Monthly × 12
Annual Cost = same CCF/per-gal logic as Metered Flow
Water waste (gal/mo per unit)
| Category | Crit | Mod | Minor |
|---|---|---|---|
| Broken Head | 2,500 | 1,500 | 600 |
| Clogged Head | 1,000 | 500 | 200 |
| Misaligned Head | 1,200 | 700 | 300 |
| Lateral Break | 8,000 | 4,000 | 1,500 |
| Mainline Leak | 20,000 | 8,000 | 3,000 |
| Valve Issue | 6,000 | 3,000 | 1,000 |
| Controller Issue | 4,000 | 2,000 | 800 |
| Backflow Issue | 300 | 100 | 0 |
| Low Pressure | 2,500 | 1,200 | 400 |
| High Pressure | 3,000 | 1,500 | 600 |
| Overspray | 2,000 | 1,000 | 400 |
| Other | 1,500 | 700 | 200 |
Typical repair cost (USD/item)
| Category | Crit | Mod | Minor |
|---|---|---|---|
| Broken Head | $25–$60 | $15–$40 | $8–$20 |
| Clogged Head | $15–$30 | $8–$20 | $5–$12 |
| Misaligned Head | $10–$25 | $5–$15 | $3–$8 |
| Lateral Break | $80–$200 | $50–$120 | $30–$80 |
| Mainline Leak | $200–$600 | $150–$350 | $80–$200 |
| Valve Issue | $100–$250 | $60–$150 | $30–$80 |
| Controller | $150–$400 | $80–$200 | $40–$100 |
| Backflow | $200–$500 | $100–$250 | $50–$120 |
| Low Pressure | $100–$300 | $50–$150 | $20–$60 |
| High Pressure | $80–$200 | $40–$100 | $20–$50 |
| Overspray | $40–$100 | $20–$60 | $10–$30 |
| Other | $100–$300 | $50–$150 | $20–$60 |
Estimates assume 5-day/week schedule, 20–30 min runtimes, 5–8 GPM/zone. Custom repair items override category estimates.