Well Testing 101

said on May 24th, 2012 filed under: Localism, Water Wells, Septic Systems, Sewers, Electric Power

Before buying rural property, or any property that relies on a well for the domestic water supply, the well should be tested.  You should also test a well any time you notice a change in the taste, color, or clarity of the water.  If you depend on a well, you should probably have the quality of the water tested every now and then as part of your general maintenance.

Hire a reliable well testing company if you want a complete test.  This test takes at least 3 and 1/2 hours and maybe longer depending upon your county requirements.  Currently, in Placer and Nevada counties, California, complete tests cost about $450.00.  If you are just testing for bacteria or mineral content, you can get a sterile container from the lab, collect the sample per instructions, take it to the lab yourself.  If the test is part of a real estate transaction, however, you should be cautious of something called “chain of custody,” because you don’t want any doubt about the source of the water to be tested.  Capiche?

What are you looking for in a complete well test?

1.  yield

2.  cleanliness

3.  quality

First, you are looking for yield (how much water does the well produce?), expressed in GPM or Gallons Per Minute.  The tester will disconnect the well  from the pressure tank (also called a hydropneumatic tank)  and/or holding tank (also called an atmospheric tank) and cause the water to flow directly from the well and through a pipe where, typically, it just dumps on to the ground.

Between the well and the end of the pipe, the water will run through a meter where the flow is determined.  Old time testers don’t even use a flow meter.  They direct the water into a 5 gallon bucket, then use a stopwatch or timer to determine how long it takes for the bucket to fill.  If it takes 1 minute for the 5 gallon bucket to fill, then the yield is . . . uh . . . 5 gallons per minute.   The meter will be checked, or the bucket filled and timed, every 15 minutes over the length of the test, usually 3 or 4 hours.

Typically, the flow will be greater at the beginning of the test while all the accumulated water standing in the well is drawn out.  At some point, the flow will level out and remain at a constant flow for the remainer of the test.  That constant flow is the true yield of the well, not the gusher you get at the beginning of the test. Some wells are so strong that the yield at the beginning of the test is the same as the yield at the end of the test 4 hours later.  That means that the well is producing more water than the pump (way down at the bottom of the well) can deliver.  Wow, that is a good well!

Second, you want to know that your well water is clean and free of bacterial contamination.  The water is collected in a sterile container and taken to a lab.  Your sample can result in one of three readings:

a.  absent (meaning there is no significant bacterial contamination). Yay!

b.  total coliform bacteria present in significant amounts.  Pooh.

Don’t freak out.  Total coliform can be treated.  Typically the treatment is easy and cheap.  You introduce a chlorine product into the well, wait a while, flush it out.  Bacteria gone!  Sometimes you have to “chlorine shock” the well more than once, and I’ve personally seen a well require 4 “shocks” to come clean.  What causes total coliform bacteria to contaminate a well?  Who knows?  A spider gets past the seal, a new pump is installed without being perfectly sterilized, dirt falls down the hole during maintenance.  There are a few wells that require regular “shocks,” but those are not typical.

c.  e. coli present.

This is bad news.  Very bad news.  Wells that show e. coli contamination often have to be destroyed and abandoned.  E. coli is dangerous, and can be fatal.  This pernicious bacteria grows in the intestines of animals (around our neck of the woods, it’s usually cows)  and is spread from the animal dung into the ground water where it flows downhill into poorly placed or poorly constructed wells.  The problem is that, even if you clean the well with chlorine, the infected ground water has found a way into the well, and it will just keep dripping and oozing into your water.

The cure?  Drill a new well in a better location.  In real estate transaction, e. coli is often a deal breaker.

Third, it is sometimes a good idea to test the water quality for mineral content, also called (ahem!) inorganic chemical group analyses.  Certain locations are notorious for heavily mineralized well waterIf you see a lot of staining in the toilet tank or bowl, or around the tub drain, or anywhere well water is present, you may want a “mineral panel.”  These tests cost from $50 for a basic panel, up to about $300 for the entire “menu.”  It usually takes a couple of weeks to get the results for a complete “panel.”

Again, don’t freak out.  Well water always contains some minerals.  Acceptable safe levels for most of these inorganics have been long established. Your  lab results will show how your water compares to these safe levels.  Even if your well water is heavily mineralized, most problems can be handled by filtration systems.

What will a $50 basic panel reveal?  Salinity, acidity, hardness, iron, and manganese.

Want to get exotic?  You can test for arsenic, alkalinity, copper, lead, saturation index (tendency to form lime scale), nitrate, sodium, mercury, nickle, boron, magnesium, chloride, sulfate, potassium, flouride, aluminum, antimony, barium, beryllium, cadmium, chromium, selenium, silver, zinc, and, of course, thallium.

You can even order a la carte and design your own mineral test!

This is what the well actually looks like.  Disappointing isn’t it?  All this hooplah over that little thing.


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To find out more about real estate in the Golden Hills of the Sierras, just call Bob at (530-906-1023) or CJ at (530-9064715) or email us at [email protected] or [email protected]

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