What kind of water pipe to use?

I live in a forested area too and fire mitigation is a BIG deal. I don't ever recall reading anything about suggested ways to mitigate forest fires that involves wetting down an area. What is generally suggested is a fire mitigation zone, a cleared area from any structures you don't want to burn. That usually includes removing any trees and brush within 30 feet of structures and then trimming tree limbs that are within 10-12 feet of the ground in a 50-100 foot parameter around structures. We are told that if you choose not to fire mitigate, then the likely hood of your structure being saved by fire fighters is a lot less. That, and they may consider not trying to save your structure as you never took the proper fire mitigation recommendations.

My opinion would be that wetting down an area will quickly evaporate with an approaching fire and probably not do much good. You would need very high volumes of water to be successful. It may be a waste of money... but don't take my opinion as fact. And, most likely I do not live in a similar environment as you.

Please do yourself a favor and look into proper fire mitigation and make the necessary changes that are recommended for your area. If you can't find anything, I'm sure a call to the local fire department can provide lots of good information for you on how to proceed.