Aloha,
From what I understand, this is the sequence of events in case of a fire;
1. Someone calls to report a fire to the police department and the police dispatch the fire department
2. Somehow (radio or cb or scanner) the volunteer fire department, located in Eden Roc Subdivision on road 8 (I do believe Ahiukau is road 8 you lucky rooster), but also serves outlying areas get the information
3. If available, the volunteer fire department responds and since they arrive first, ascertains whether or not the County fire department needs to respond
4. If the County does not need to respond then the volunteer fire department calls and lets them know, if so, visa-versa
There are NO fire hydrants located in this subdivision!
The volunteer fire department has a fire truck with a water tank attached and uses that for its service. If it does need more water than that, there is a tank on road 8 with water. Of course, if you can install an attachment to your tank to accept their hose that would be a golden goose. I dont know what size adapter they need. I dont know their direct number but the Eden Roc Estates Association number is 808-968-8484, you can leave a message and they should pass your question on to the volunteer fire department who should be happy to tell you what size.
If you have a 15,000 gallon tank you may have the largest in the subdivision; whether or not that is sufficient would depend on the extent of the fire. And at 1,8oo sqft, you may want to ask the county if that tank is large enough
Good luck, youre on the right track
Also, if the County fire department responds to your fire they may need a different size adapter. Heres their website.
http://co.hawaii.hi.us/directory/dir_fire.htm