Water

"Water water everywhere and not a drop to drink." Don't let this be you and your loved ones. It is the first tab because it is the basis for all life on earth. And clean, potable water is increasingly - and most unfortunately - becoming a commodity. 
We decided that a good quality water filtration and purification system was the way to go. This is not the right place in your budget to cut corners or skimp on quality. After much mind numbing research and consultations, we have gone with the Lifesaver jerrycan.
"Like the bottle, the LIFESAVER jerrycan uses a highly advanced ultra filtration system, originally developed for industrial applications.  It will remove bacteria, viruses, cysts, parasites, fungi and all other microbiological waterborne pathogens.  It does all this without the aid of any foul tasting chemicals like iodine which is a banned substance within the EU.  The jerrycan holds 18.5 litres (approx 5 gallons) and can process up to 20,000 litres of water.  There are 2 consumer versions, a military and an AID version."

You will also need different containers to haul it, store it, transport it and drink it. So think about your daily habits and anticipate those needs. Try where possible to utilize already existing resources, and by this I mean, stainless steel and some better quality plastics will last forever, so hit those yard sales and thrift stores and find ones already existing, avoid buying new ones as this only creates false demand. This also applies to other kitchen resources. If you don't already have it, try to find a used one.