toolkit

When you're working in the field, certain tools are indispensable. You have the obvious:

extra large flat-head screwdriver for prying stuff loose
socket set (and wrench!) for well covers
hammer to loosen well covers and then to close them again
socket set extender to avoid destroying your knuckles
utility knife
small flathead screwdriver
small phillips head screwdriver
tape measure
duct and electrical tape
pliers
2 adjustable wrenches
fat and skinny sharpies
ballpoint pens (lots)
Spare bolts for well covers

Then you have the random stuff. These are equally indispensible:

teflon tape
5-sided well key
hose clamps and various small heavy objects to weight tubing
tubing connectors of all sizes
a drain snake (that may need some explaining...)
50 feet of mason line, generally attached to a hook and frayed all to hell
ruler with increments of inches and 1/10 of a foot
magnet
miscellaneous batteries
safety glasses and work gloves
footvalves (little plasticky doohickeys that cost like $35 each)
spare lengths of silicone tubing
a couple of vials or jars
zip ties
hand lens
strapping tape
WD-40

And the stuff that doesn't fit in a toolbox per se...

pry bar
bolt cutters
buckets
bailer for interesting liquids

What have I missed? Let me know...

You may be thinking that this is a seriously long list of crap to haul around. I tend not to have every single item at once because I'm forever breaking/losing things. I can't tell you how many bolts, zipties, socket attachments, pens, and rolls of tape I've gone through. And yes, you can do almost anything with a pair of pliers, a hammer, and a knife, but it's a hell of a lot easier if you're using the right tools. Some stuff, like the teflon tape and the footvalves, is only used occasionally, but it's the sort of thing that you'll forget when the closest hardware store is 45 minutes away and probably doesn't have what you need anyway.