What are the best ways to test for water quality in your house? The water is from a well, not town water. Are there any products that can continuously test the water coming in (versus manually sampling the water every so often)?
“Water quality” is not one-dimensional … what kind of contaminats do you want to test for?
If the answer is “everything” or “I don't know” then start by finding a reputable local lab, describe your concerns to them, and see what they recommend based on their knowledge of the water in the area. Once you have done a thorough one-time test, you will have a basis for deciding what (if anything) to test for on an ongoing basis.
To find a lab, you could start by calling the water authorities in your town or surrounding towns. At least in my case, they were happy to recommend a local, independent lab.
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
- Yellow or orange color, may cause stains on laundry and fixtures, and may have a bitter taste
- 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)
- 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)
You CAN buy (on the order of 10 dollars) a test kit from your local home center. These are usually a package of strips that you dip in the water. These strips contain reactants that change color to indicate various contaminants in your water. Having said that, those kits are not terribly accurate, but they will be reasonable. If you have a lot of something in your water, the kit will flag a problem. Just don't expect high accuracy.
Of course, you can always call in the water people - those who will try to sell you a complete water treatment system, at a cost of many thousands of dollars. They have a vested interest in selling you something. They can test your water too, though not as accurately as an independent lab would do.
A reputable, independent lab will be far more accurate, and has no vested interest in a sale. But expect to pay a reasonable fee for that service.
So to answer whether there is a "good" way to test water quality, we would need to understand how much accuracy you want to see, and how much money you would be willing to spend.
If we're just talking about hardness, there are water softeners that can measure the hardness in real time and adjust their regeneration frequency to match (for example, Culligan calls theirs an "Aqua Sensor".
There are also realtime TDS (total dissolved solids) meters that are used on the output side of lab-grade filtration systems. I'm not sure if there are similar units for the input side of things.
Other than that, I don't know.
Just to answer the basic question; there is no such thing as a continuous stream "water quality monitor".
Just like Gregmac and Vebjorn stated in their posts above, there are many elements which determine water quality.
I can tell you based on working in power plants, and large physical plants we had (at only a handful of facilities mind you...) several systems which would do continuous monitoring and chemical injection, but it was generally monitoring only one parameter - such as pH or TDS. Most water quality analysis at power plants is still done by hand because the equipment to automate the testing is either very expensive, not practical to use or vaporware.
And mind you, these are facilities that use much more water than all of us (and I mean like every member of diy.stackexchange) combined on a daily basis.
If you're in the US, talk to your local county extension office. If they don't do water testing, they'll know who to talk to.
If you're in a rural area, be sure to test in the spring after the local farmers have applied fertilizers.