A water purveyor's perspective
Bill Kirkpatrick is an Engineering Manager at East Bay Municipal Water District in California (EBMUD), a public utility company that supplies water to 1.3 million people in 20 cities in northern California. During the Summit in Chicago, Mr. Kirkpatrick presented a water purveyor’s perspective on home fire sprinklers, taking into account the balance between water supplier reliability issues and the issues of service, cost and liability. Download his presentation.
Video: Bill Kirkpatrick says that most communities in the United States would not need to upgrade their water infrastructure systems because of home fire sprinkler requirements.
Video: Bill Kirkpatrick says that when a community has home fire sprinklers installed, it benefits the community and water purveyors alike.
Water purveyor’s reliability issues
- Water supply – store sufficient water to meet total demand
- Water facilities – maintain facilities that can handle the service
- Water quality – provide quality that meets industry standards
- Cost – retain and maintain cost efficiency
General policy issues – Balancing competing interests
The sprinkler discussion
- Background – Working in 2008 and 2009, the Residential Fire Sprinkler/Water Purveyor Task Force (Task Force) included representatives from the fire service, water agencies, building industry, and fire sprinkler design industry. Task force worked together to identify water issues and engage in code change discussion.
- Read the Residential Fire Sprinkler/Water Purveyor Task Force (Phase I) Final Report
- Task Force worked to reconcile pre-2011 practice vs. new code - Previously the code did not specify a domestic allowance for combination fire and domestic meter sizing. EBMUD sized meters based on the sum of the fire flow requirement and the peak domestic demand (all fixtures running), leading to a higher design flow than the new code suggests.
- EBMUND water meter study – Demands and domestic allowance based on the American Water Works Association Research Foundation (AWWARF) study:
- 20% of peak flows less than 5 gpm
- 90% of peak flows less than 15 gpm
- EBMUD found this study to be representative of urban water use. Since 5 gpm only covered 20% of the peak flows we wanted to research further.
Typical household fixtures and flows
- Toilet – 4 gpm
- Sink – 2 gpm
- Shower – 3 gpm
- Washing machine – 4 gpm
- Dishwasher – 3 gpm
- Irrigation – 10-15 gpm
AWWARF study shows that irrigation demand peaks in the morning and evening, which coincide with the time 48% of residential fires occur (NFPA Home Structure Fires). Irrigation and fire demand could be simultaneous; thus 90% of peak instantaneous flow demand is 15 gpm.
Standardization - EBMUD does not determine meter size on an individual basis; we need one service configuration that works for all, including customers at the high end of the zone. We find that the 1.5/1 will work for 70% of typical applicants. Private side lateral should increase back up to 1.5 inch to the house and domestic / fire split. Minimizing size minimizes cost.
“Statistically at EBMUD, about 70% of the time applicants will fall within the capacity of the 1-inch meter, regardless of domestic allowance applied. For the other 30% who need a 1.5-inch meter, that’s what’s required already today due to domestic fixture count, so there wouldn’t be a change.“
Water shut-off risk - What is fire probability given statistical opportunity? Assuming same internal causal liabilities, real risk may actually be much lower --- approaching zero.