CISA's sector pages say that nearly every industry relies on electric power and fuels, that communications depend on energy for towers and central offices, and that water and healthcare depend on both. A power outage can therefore become a communications, water and hospital problem within hours.
The dependencies, in CISA's words
From the sector pages:
- Energy. Nearly all industries rely on electric power and fuels. The sector relies on pipelines, which links it to transportation.
- Communications. Energy supplies power to cellular towers and central offices, and communications are used to monitor and control electricity delivery. Emergency services rely on communications for coordination, alerts and 9-1-1 call reception. Transportation supplies diesel fuel for backup generators.
- Water. Firefighting and healthcare depend on water services. The sector also links to energy, health and critical manufacturing.
- Healthcare and Public Health. Depends on communications, emergency services, energy, food and agriculture, information technology, transportation and water.
A loop to watch
Power runs the tower. The tower carries the signal that monitors the grid. Backup generators need diesel, which arrives by road. Each link is ordinary on a good day. Together they form a loop that is only tested in a bad one.
How to use this for planning
- Write down what your site needs from each of the other sectors: power, a data link, water, fuel, staff who can reach you.
- For each, note how long you can run without it.
- Mark the item with the shortest time. That is your first drill.
- Ask each supplier what their own backup is.
Software is a dependency too
CISA's pages describe physical and service links. Modern sites also depend on software: control system updates, remote access tools, vendor portals. A dependency inventory, including SBOM based scanning of the code you run, belongs on the same map. Safeguard supports SBOM and dependency scanning for that part.
Writing it down as a table of hours
Turn the map into numbers. For each dependency write the hours you can run without it: generator fuel, battery backup on radios, stored water, paper forms. Where you do not know, write "unknown" and treat that as the task. A list with five unknowns is a better plan than a list with five guesses.
Share it with the neighbors you depend on. A water utility and a hospital that compare their numbers often find one has a shorter margin than the other assumed.
Try it yourself
Click through it at your own pace, or open it full screen.
Look at how a software dependency list reveals things you did not know you relied on.
Quick check
Which sector does CISA say nearly every industry relies on?
Energy, for electric power and fuels.
Why does a hospital care about the communications sector?
CISA lists communications among the sectors the health sector depends on for continuity and service delivery.
Sources
Last reviewed: 19 October 2026.
