ISO Information

Currently, the district is rated as a Class 3/8B with the Insurances Services Office, Inc. (ISO). 50% of the ISO rating is for the fire department, 40% for the water supply and 10% for the dispatching capabilities. The district has made substantial improvements in all three categories

ISO Letter Download Link

Public Protection Classification rating factors

ISO’s Public Protection Classification system has been in use since the early 1900’s, and has been continuously modified and refined over that time. The Fire Suppression Rating Schedule (FSRS) looks at a great deal of specific information about the fire department, the water supply, and the types of property in the community, and uses a fairly complex process to evaluate that information. In general, here are the factors the Public Protection Classification system looks at:

  • Water Supply:
    This is the most important single factor and accounts for 40% of the total rating. This part of the survey focuses on whether the community has sufficient water supply for fire suppression beyond daily maximum consumption. ISO surveys all components of the water supply system, including pumps, storage, and filtration. They observe fire flow tests at representative locations in the community to determine the rate of flow the water mains provide. They also count the distribution of fire hydrants no more than 1,000 feet from representative locations.
  • Fire Equipment:
    This accounts for 26% of the rating. There are some specific minimum equipment requirements and specifications and additional equipment standards for both fire engines and ladder trucks based on the numbers and types of structures in the community. Regular testing of the equipment is also a factor. 4 points of the 26 is the credit for distribution and is based on the percent of the built upon areas of the district which have an adequately equipped, responding first-due engine company within 1.5 miles and an adequately equipped responding ladder company within 2.5 miles. Fire station locations become very important in the credit for distribution.
  • Personnel:
    This factor accounts for 24% of the rating. 15% of that is based on the numbers of firefighters available for the initial response and how quickly the firefighters can respond. ISO reviews the average number of firefighters and company officers on duty with existing companies. The other 9% reflects the initial and ongoing training the firefighters receive.
  • Dispatching/Fire Alarms:
    How well the fire department receives and dispatches fire alarms accounts for the remaining 10% of the rating. ISO will evaluate the communications center, in our case the Denton County Sheriffs Office. ISO looks at the number of operators at the center, the telephone service, including the number of telephone lines coming into the center, and the listing of emergency numbers in the telephone book. Field representatives also look at the dispatch circuits and how the center notifies firefighters about the location of the emergency.

Texas awards up to five points extra credit for training, adoption of a model fire code, in service inspections, staffing of the fire prevention and inspection office, plans review, prevention, public education, and arson investigation.