Water Supply
Water Supply for Exterior Wildfire Sprinklers
Zones water in turns, so a properly sized tank lasts for hours.
20 to 30 GPM
per zone, generally one zone at a time
60 to 80 PSI
design pressure, booster pump if short
8 hours
runtime goal at full defense
How the water is used
Watering steps up with the threat.
Each zone puts out 20 to 30 gallons per minute. Zones generally run one at a time unless the home's supply line is large enough to run more. The system cycles through zones and rests between rounds, and the rest gets shorter as the fire gets closer. Example: 3,000 sq ft roof, 4 zones.
Level 1
3 to 5 milesPre-wet
Each zone runs 2 to 4 minutes, then the system rests at least 15 minutes between cycles until the threat clears.
Watering about 35 to 50% of each hour
520 to 775 gal / hour
Level 2
1 to 3 milesSaturate
Each zone runs 3 minutes. 10 minute rest, then repeat.
Watering 55% of each hour
820 gal / hour
Level 3
Under 1 mileFull defense
Each zone runs 3 minutes. 5 minute rest. Repeats until the fire passes.
Watering 71% of each hour
1,060 gal / hour
Water starts only for a confirmed fire. At Level 1 the system waters only when conditions push the fire toward your home. Most nearby fires never get past an alert.
Tank sizing
The right tank for your home.
Tanks are sized to run full defense for the hours you choose, about 5,000 gallons for 4 hours on a 3,000 sq ft roof.
4 hours
6 hours
8 hours
3,000 sq ft
3 to 4 zones
about 1,060 gal / hour
4 hours
6 hours
8 hours
4,000 sq ft
4 to 5 zones
about 1,350 gal / hour
4 hours
6 hours
8 hours
How long a 5,000 gallon tank lasts.
On a 3,000 sq ft roof with 4 zones. Most fires spend hours at Level 1 or 2 first, so real use is usually lower.
Pool backup
Have a pool? It can be your tank.
Your system can run straight from a pool or storage tank, or from city water with your pool or tank as a backup that switches over automatically if pressure drops. Either way, the house is not left depending on city pressure during a fire.
18,000 gal pool
A typical backyard pool
- 1
We connect the sprinklers straight to your pool or storage tank, or to city water with the pool or tank as an automatic backup.
- 2
When a fire triggers the system, a pump sends that water to your roof and perimeter sprinklers. No one has to be home.
- 3
City water pressure can drop during a fire. Your own water supply does not depend on it.
How long the pool lasts (3,000 sq ft roof, 4 zones)
That is more than twice the 8 hour goal at the heaviest setting. Pool homes can often use a smaller tank, or none. The pump needs power during an outage, so pair it with a generator or Powerwall.
How our systems are programmed
Three homes. How long the water lasts.
Each home's watering program, water used per hour, and how long a 5,000 gallon tank would last. Calculated at 25 GPM per zone (zones run 20 to 30 GPM).
Hillside Estate
3 stories built into a hillside. 5,000 sq ft roof and a pool.
Level 1 · 3 to 5 miles
2 to 4 min each zone, 15 min rest
520 to 775 gal/hr
Tank lasts 6.5 to 9.5 hrs
Level 2 · 1 to 3 miles
4 min each zone, 10 min rest
920 gal/hr
Tank lasts 5.4 hrs
Level 3 · Under 1 mile
4 min each zone, 5 min rest
1,140 gal/hr
Tank lasts 4.4 hrs
With an 18,000 gal pool: about 23 to 35 hrs at Level 1, 20 hrs at Level 2, 16 hrs at Level 3.
Skyline Home
Hexagon home with an attached 1,200 sq ft garage. 3 zones.
Level 1 · 3 to 5 miles
2 to 4 min each zone, 15 min rest
430 to 665 gal/hr
Tank lasts 7.5 to 11.7 hrs
Level 2 · 1 to 3 miles
3 min each zone, 10 min rest
710 gal/hr
Tank lasts 7 hrs
Level 3 · Under 1 mile
3 min each zone, 5 min rest
960 gal/hr
Tank lasts 5.2 hrs
Mountain Retreat
Two-story home, about 2,000 sq ft roof, plus a detached garage. 4 zones.
Level 1 · 3 to 5 miles
2 to 4 min each zone, 15 min rest
520 to 775 gal/hr
Tank lasts 6.5 to 9.5 hrs
Level 2 · 1 to 3 miles
3 min each zone, 10 min rest
820 gal/hr
Tank lasts 6.1 hrs
Level 3 · Under 1 mile
3 min each zone, 5 min rest
1,060 gal/hr
Tank lasts 4.7 hrs
Zones run one at a time, so only one zone draws water at any moment. Every program repeats until the threat ends. Bars compare against 15 hours.
A complete exterior wildfire defense system
Three factors decide whether it works.
Water supply, satellite internet, and backup power are the three critical factors that determine how effectively an exterior sprinkler system defends a home from wildfire. If one fails, the system cannot do its job.
Water Supply
Enough water, at enough pressure, for as long as the fire lasts. That means a tank sized to your home, a pool connected as backup, and a system designed to run at 60 to 80 PSI, with a booster pump if the home's pressure falls short. City pressure can drop during a fire. Your own supply does not depend on it.
Satellite Internet
Local internet often fails during a wildfire. Satellite internet keeps the controller connected for fire alerts, live updates, and remote control from anywhere. If the link drops, the controller keeps running its saved defense programs on its own.
Backup Power
Power lines usually fail during a wildfire. Every pump drawing from a pool or tank needs backup power, a generator that starts automatically when the power goes out or a home battery. No power to the pump means no water from the tank.
Built right
The system has to be as good as the water.
Water, connectivity, and power make a system possible. Design and build quality make it effective, hour after hour, when the fire arrives.
01
Good design
Every valve, part, and pipe is laid out to FireRoofs design rules so water reaches each zone as planned. Vertical exterior pipes are painted to match your home.
02
Good coverage
Rooftop sprinklers keep the roof surface wet. Eave and wall sprinklers wet the exterior walls, vents, deck attachment points, and Zone Zero, where embers collect and most homes are lost.
03
Copper piping
Copper pipe throughout. No plastic supply lines that can soften or fail in radiant heat.
04
Commercial-grade sprinkler heads
Commercial-grade rotors on the roof and brass eave and soffit heads, built to throw an even, protective curtain of water for hours.
05
Reliable controller
Schedules and fire-response rules are stored on the controller at your home, so the system runs its defense programs even when the internet is down.
06
Quality valves
Commercial-grade zone valves open and close each zone in sequence, cycle after cycle, for as long as the threat lasts.
07
Well-designed hydraulics
Zones are sized and sequenced so no single zone exceeds your supply. Pressure and flow are measured on site before the design is final.
Learn more about exterior sprinkler systems, see what a system costs, or read why some homes survive wildfires.
Questions
Water supply, answered.
How much water do exterior wildfire sprinklers use?
Each zone puts out 20 to 30 gallons per minute. Zones generally water one at a time, then rest, unless the home's supply line is large enough to run more. On a 3,000 sq ft roof with 4 zones, the system uses about 520 to 775 gallons per hour while pre-wetting, 820 gallons per hour while saturating, and 1,060 gallons per hour at full defense.
What size water tank do I need for wildfire sprinklers?
FireRoofs sizes tanks to run full defense for the hours you choose. For a 3,000 sq ft roof, that is about 5,000 gallons for 4 hours, 7,000 gallons for 6 hours, and 9,000 gallons for 8 hours. For a 4,000 sq ft home, it is about 6,000, 9,000, and 11,000 gallons. Your FireRoofs design sets the final size.
How long does a 5,000 gallon tank last?
On a 3,000 sq ft roof with 4 zones, a 5,000 gallon tank lasts about 6.5 to 9.5 hours at Level 1, 6 hours at Level 2 and 4.7 hours at Level 3. Most fires spend hours at Level 1 or 2 first, so real use is usually lower.
Can my swimming pool supply my wildfire sprinklers?
Yes. A typical 18,000-gallon pool holds about 17 hours of the system's heaviest watering on a 3,000 sq ft roof with 4 zones, and longer at lower levels. The system only uses water when a confirmed fire threatens your home, so a pool usually outlasts the event. The sprinklers can run straight from the pool, or from city water with the pool as an automatic backup.
Why do satellite internet and backup power matter?
Power lines and local internet often fail during a wildfire. Any pump drawing from a pool or tank needs backup power, ideally a generator that starts automatically or a home battery. Satellite internet keeps the controller connected for alerts, remote control, and outside fire data. If the connection drops, the controller keeps running its saved defense programs.
What water pressure does an exterior sprinkler system need?
FireRoofs designs systems to run at 60 to 80 PSI, with a booster pump installed if the home's pressure falls short. Pressure and flow are measured during your site survey.
Know your water before fire season.
We measure your pressure and flow on site, then size the tank, pool connection, pump, and backup power for your home.
Estimates only. Each zone puts out 20 to 30 gallons per minute. 3,000 sq ft figures use 25 GPM; 4,000 sq ft homes plan at 30 GPM. Most fires spend hours at Level 1 or 2 first, so real use is usually lower. Your FireRoofs design sets the final size.