Well here in Ireland there's a lot of country homes that are off-grid so to speak. They don't have a mains water supply and waste sewage system. The homes are often built with cess pits for sewage which need emptying occasionally (not as often as you think) and water pumped up from a well bore.
There's been quite a business in Ireland with water diviners who locate underground water streams and bore the wells, due to the building boom in Ireland ofc. Many of these country homes are up for cheap rentals now too as the owners find that they can't sell them etc.
The water diviners don't use wooden sticks btw lol, but ground penetrating radar and old geological survey maps.
Ireland is festooned with ground water ofc, your area might not be, I only know about the UK and Ireland.
To test the water you just take samples to a lab that specializes in water testing..again many of these in large towns in Ireland. Some govt/local councils also offer testing. You'll find that good ground water has seeped through rocks for many years and become naturally filtered. Here in Ireland and the UK the rock is primarily limestone in most cases where the job is done, resulting in quite a bit of calcium which makes for rather hard water (you'll see it gathering around the element of a kettle for example) , there's also quite a few other minerals in the water , perhaps calcium fluoride but your body can deal with this type of fluoride far better than sodium fluoride or God forbid..fluorosilic acid (a hellaciously toxic and corrosive acid) which is what is normally added to mains supply water.
It is quite literally your own mineral water supply, tastes great and is good for you. The best wells must be bored to a depth below at least the first confining bed, this results in 100+ yr old water that is very well filtered and free of harmful bacteria but it is expensive to drill and pump from this depth.
I have a great laugh at relatives who turn their nose up at it, I tell them I've been drinking it for yonks and it's done no harm to me. I haven't even had so much as a sniffle in over 2 years now.
I've seen some places get a surface water supply which is often "peaty" in appearance...now this is indeed a bit dodgy and liable to bacterial infection by cryptosporidium or strep for example.
It is also possible to sometimes tap what is often called "fossil water", a good example of this would be in Libya where they discovered a vast (we're talking thousands of cubic kilometres) underground aquifer that held water that had seeped down perhaps thousands of years ago. It's very pure indeed and of immense value to the area for obvious reasons.
Wiki sources:
http://en.wikipedia.org/wiki/Nubian_...Aquifer_System
http://en.wikipedia.org/wiki/Ground_water
A typical well boring company in Ireland:
http://www.build.ie/company_474394.htm
EDIT- forgot to add info about septic tanks/ cesspits
http://en.wikipedia.org/wiki/Septic_tank