inner tubes or maybe a roofing supply store. The tubes would be my first guess,I would think that even a larger bicycle tube would yield enough rubber if split and opened up. The water system on my property is a well that pumps into a 500 gal holding tank before it is pumped to the houses, so I always have 500 gals in reserve. I also have water rights to a creek a little bit aways so I have a 1" line that runs down to near the pump house. This is my back up, along with irrigation and watering animals, I can boil it if need be. Also close by the place there is a creek that emerges from the earth. If absolutely had to I could "bucket brigade" daily consumable water to the place. I really should get a generater some day. I think I would like to have that in a metal building, or build a Faraday cage around it though. I am going to check into the hand pump also.Hmmm, still lots to do apparently
. As an after thought,I wonder if I have enough drop on my gravity line to power a generator? Something else to look into.