If this aerial photo is accurate, then the reactor complex is directly adjacent to the Pacific Ocean - for all practical purposes an infinite supply of seawater.

http://www.imgstant.com/-open-channel-blog-2007-japan-quake-was-wake-up-call-on-nuclear-safety-474x500/msnbcmedia2.msn.com%7Ci%7CMSNBC%7CComponents%7CInteractives%7C_swf%7CNews%7Cjapan_quake_2011%7CFukushima-Daiichi-Nuclear-Power-Station2.jpg/

Problems of lack of water must be very local lack of means to pump enough water to the places where it would do the most good.

If the proximity of the ocean is a given, I would have thought ship based pump and power systems would have been deployed. I can only guess the magnitude of the need exceded such straightforward solutions. [Shudder.]