Most people shopping for a wildfire pump start with one question: how many GPM is enough? It's the wrong first question. A bigger number on the box doesn't help if your hose, your lift, or your tank can't keep up with it.
Here's how I'd size a pump for a rural place, in the order I'd work it out.
Start with the job and your flow
Write down what the pump has to do before you look at any pump. Most rural owners want one or more of these:
- Run sprinklers on the roof and the ground around the house
- Wet down outbuildings, fences, and fuel on the edges of the property
- Fill a water truck or ATV sprayer
- Run a hose line for putting out small spot fires
Sprinklers are a steady, long-running load. Hose lines are short bursts that want more pressure and volume.
For sprinklers, find the spec sheet on the heads you plan to use. Flow depends on the nozzle and the pressure, so use the manufacturer's numbers, not a guess. Multiply by the number of heads running at the same time, then add a hose line or two if you want one. Give yourself some margin, because real systems lose a little to long hose runs, elevation, and worn parts.
Pressure matters as much as volume. Every foot you pump uphill costs you pressure, and long hose or small-diameter pipe costs you more. A property with a pond at the bottom and a house at the top needs a different pump than a flat lot with a tank next to the shop. Look at the pump's pressure rating, not just its GPM. Our Dry Lightning 3000 is rated up to 140 PSI, which leaves room for lift and long hose runs.
Match the pump to the water supply
This is where people get burned. Two numbers decide how long you can run:
- Tank or pond volume. A pump moving 150 gallons a minute empties a 5,000-gallon tank in about half an hour. Run fewer sprinklers, and the same tank lasts a lot longer.
- Refill rate. If a well or spring feeds the tank slowly, you're limited by that, not the pump.
Don't buy for the biggest flow you can imagine. Decide how many hours of sprinkler time you want, divide your usable water by those hours, and see what flow that gives you. Often the answer is lower than people expect, and a bigger tank is a better investment than a bigger pump.
Also check the suction side. Keep the pump close to the water and the suction hose short and tight, with no air leaks. A good pump with a bad suction line won't prime or will lose flow.
Think about who starts it
A pump is only useful if someone can start it. A lot of ranch and cabin owners aren't home when fire season gets ugly, and the road may be closed by the time you could get back.
That's why I build remote-start systems. Our Dry Lightning 3000 wildfire pump runs on a Honda iGX390 engine, moves up to 150 GPM, and starts and stops from your phone over WiFi or SMS, from anywhere. It also alerts you if the pump stops running, such as when it runs out of gas, or if the tank runs low. A pump that quietly stops is worse than no pump when you think the house is covered.
Test it with everything running
Paper math only goes so far. Once the pump, hoses, and sprinklers are hooked up, run everything at once. Watch the pressure at the farthest head, time how fast the tank drops, and look for leaks, kinked hose, and any sprinkler that isn't throwing water where you need it.
Write down what you learn and tape it inside the pump shed door. If someone else has to run it, they'll need it.
One thing to do this week
Measure your water. Find out how many gallons your tank, pond, or well can really give you, then divide that by the flow of your planned sprinklers to see how many hours you'd actually have. If the answer is less than you'd want in a long fire, you've found your real limit, and it's better to learn that in November than in August.