NOWi Multifamily Water Usage Benchmark Study
NOWi completed a 30-day study of water usage at low-rise and mid-rise multifamily buildings in San Francisco during June and July of this year. The data was gathered from 129 buildings being monitored by NOWi for water usage and leakage.
Water Usage at Buildings with No Water Leakage
To determine normal usage, we focused on the 102 buildings with 1,873 units that had no leakage. The number of units per building ranged from 5 to 62, primarily consisting of single-bedroom apartments.
Average usage was 53.2 gallons per day per unit (GPDPU). Usage per unit ranged from 33 to 82 GPDPU, with 96% falling between 45 and 75 GPDPU and 81% between 45 and 65 GPDPU.
Key Insight: If GPDPU exceeds 80, leakage is highly probable. For buildings with more than 10 units, leakage is likely when usage exceeds 70 GPDPU.
Usage at Buildings with Leaks
During the 30-day study, 21% of the buildings had leaks, accounting for 12% of total water usage. These buildings had an average usage of 99.7 GPDPU, significantly higher than non-leaking buildings.
Total water consumption for all buildings was 5.1 million gallons, with 612,000 gallons lost to leakage. At the average U.S. water and sewer cost ($0.016/gal.), this equates to $363 per building per month.
Projection of Water and Sewer Costs
Water costs are rising. In San Francisco, the current cost is already $0.033 per gallon, making the cost of leakage per building in this study approximately $687 per month.
Takeaways
- For multifamily buildings, 80 GPDPU is a strong indicator of leakage; for buildings with over 10 units, 70 GPDPU is a reliable benchmark.
- On average, 12% of a multifamily building’s water usage is due to leaks.
- The financial impact of water leakage is already significant and continues to grow.
The Solution: Real-Time Water Monitoring
Real-time, whole-building water monitoring is a low-cost, high-ROI solution for reducing multifamily water waste and damage. When installed in older buildings prone to leaks, NOWi’s water monitors pay for themselves in just 2-3 months. Across an entire portfolio, payback is typically under a year.