Is there a good way to test water quality in your house?
There are MANY things that determine quality of water, common ones being:


"Nuisance" Bacteria

Not always harmful, but they do release iron and sulfur into the water during their life cycles, and form a biofilm on the well surfaces

Disease-causing bacteria

Most common are e. coli and coliform, but can also include fecal coliform and fecal streptococci among others
You don't want any of these in the water

Iron 

Yellow or orange color, may cause stains on laundry and fixtures, and may have a bitter taste 

Manganese 

causes black or purple color in water and may stain fixtures, and cause a bitter taste 

Hydrogen sulphide (sulfur)

Smells like rotten eggs
Can be naturally occurring, and sometimes be caused by bacteria 

Hard water 

Caused by calcium carbonate (salt) 

Lead

Can be caused by leaded solder, and old brass plumbing components. 
It's a neurotoxin which is quite dangerous to drink 

Sand or grit 


Most jurisdictions have their own set of guidelines for acceptable levels of about a hundred different attributes (eg, here are the EPA contaminants limits, to my knowledge in North America, the local standards are is at or below these levels).



There are currently (to my knowledge, at least) no continuous processes for checking bacteria -- though I do know of at least one company who has been working on it for commercial applications (I would guess it would cost upwards of $20k). There are some sensors that can monitor other attributes. Most are prohibitively expensive for a home (conductivity and pH come to mind that could be done for a couple hundred dollars).

Here's the thing though - most of the quality attributes are unlikely to change, definitely not fast enough to actually monitor on your house. Contamination from bacteria can increase over time if your well is biofouled as the bacteria grows, but otherwise, unless you have a source of surface contamination (such as a poorly-constructed well that is not sealed properly, a dug well, or a well with direct influence from a body of water) then generally the water quality will be fairly steady. 

In Canada at least, most local public health units will test for e.coli and total coliform for free. You can also take your water to a lab to do a full analysis, or to a company that specializes in water treatment to do this for you. Be sure to pick one that uses an accredited lab though -- some fly-by-night/shady treatment companies will test "in house" looking for some really basic attributes, but are actually more interested in selling you a softener and a salt contract than treating the real problem (eg, doing a clean-out and then shocking your well every month or two may kill off the bacteria causing the iron or manganese in the first place -- but they make a lot less money if you do that). 

One option for home testing is water test strips (eg, like SenSafe makes). These are relatively cheap, and you can do them at home. Becareful though, it's not really possible to measure your water quality or safety using just these strips. They can help give you an idea, and check that your treatment is working, but don't base your health on these alone. Talk to a professional that understands the chemistry of the water and how all the different factors interact to come up with treatment options.

The EPA has a decent site about Private Wells, you may want to check it out for more information.



(Note: my dad ran a water treatment company for over 25 years, so although I am by no means an expert, I did pick up a few things)