Interpreting a Water Report: How to Make the Most of the Information You Have.

Photo courtesy of Freedigitalphotos.net

So you have been reading my blogs and now before you sits a water quality report! Are you asking yourself “now what?”  It says you have a pH of 6.84 and a Alkalinity of 37.3… is that good or bad?  Well read on my friends as we delve deeper into deciphering a water report.

pH: Potential of Hydrogen.  It is the measure of the concentration of hydrogen ions (H+).  pH is measured on a logarithmic scale of 1-14; 1 being most acidic & 14 being most alkaline.

  • Acceptable range is 6.5-8.0
  • <6.0 or >8.0 can cause severe problems
  • pH influences the availability of plant nutrients and other elements.

Alkalinity: Think of this as the ability of water to neutralize acid.  The higher the alkalinity the more acid it will take to lower the pH of the water.  Alkalinity is a measurement that incorporates the amount of bicarbonates, carbonates, and hydroxides joined to calcium, magnesium, & sodium.  Alkalinity is expressed in parts per million (PPM) of Calcium Carbonate (CaCO3.)

  • Anything above 120 PPM CaCO3 may cause a gradual increase in the pH of your potting medium.
  • Low Alkalinity water (less than 60 PPM CaCO3) is not able to neutralize sufficient amounts of acid as such the recurrent use of acidic fertilizers may result in a decrease in the pH of your growing medium.

Electrical Conductivity (EC): A measure of the conductivity of a solution.  As the level of mineral salt dissolved in the water increases so does the solution’s conductivity.  EC is often expressed in mhos (reciprocal ohms.)  Most water reports express EC in the smaller unit mmhos/cm or millimhos per centimeter.

  • Acceptable range is 0.5-0.75 mmhos/cm
  • Problematic range is 0.76-3.0 mmhos/cm
  • The severity of the problem will be determined by two factors:
    • What compound is responsible for the elevated EC?
    • How high the EC is.

Sodium Absorption Ratio (SAR): is a measure of the suitability of water for use in agricultural irrigation. It defines the sodium (Na) hazard by comparing the concentration of sodium to the concentration of Calcium and Magnesium.  A High SAR value can cause reduced porosity in soils and create a “salt crust” on the surface which will prevent water from being absorbed by the soil.  Fine soils (i.e. clays) are affected more than large particle soils (i.e. sandy soils.)

  • Acceptable range is <10 mEq/L
  • Problematic range is 10.1 – 18 mEq/L
  • Severe problem range over 18 mEq/L
    • (mEq/l is short for milliequivalents per liter)

Phosphate (PO4-P): Commonly found in groundwater and fertilizers.

  • Acceptable range is <1.2 ppm
  • Problematic range is 1.2 – 2.4 ppm
  • Severe problem range over >2.4 ppm
    • Too much phosphates can cause algal blooms in runoff water followed by significant decrease in dissolved oxygen
    • Manage with reverse osmosis filters or build fertilizer program around the levels in your water supply

Potassium (K+): Originates from dissolved rock, soil, and fertilizer.

  • Acceptable range is <20 ppm
  • Problematic range is 20 – 50 ppm
  • Severe problem range over >50 ppm (can cause foliar damage)
    • High levels can increase levels of Potassium in plant tissue thereby creating nutrient antagonism of Nitrogen or Magnesium
    • Manage with reverse osmosis filters

Calcium (Ca+2): Originates from dissolved rock, limestone, gypsum, soil, or fertilizer.  High levels of calcium form lime deposits when combined with CO3 or HCO3.

  • Acceptable range is <25 ppm for soil and water hazard but <60 ppm for ideal foliar levels
  • Problematic range is 25 – 250 ppm for soil and water hazard but 60 – 100 ppm for problems with foliar injury
  • Severe problem range over >250 ppm for soil and water hazard but >100 ppm for severe foliar injury

Magnesium (Mg+2): Originates from dissolved rock, limestone, dolomite, soils, and fertilizers. High levels of magnesium form lime deposits when combined with CO3 or HCO3.

  • Acceptable range is <20 ppm
  • Problematic range is 20 – 40 ppm
  • Severe problem range over >40 ppm

*When designing a fertilizer program remember the ideal ratio of K:Ca:Mg is 4:2:1

Zinc (Zn):  Occurs naturally in small amounts.

  • Acceptable range is <2.0 ppm
  • Problematic range is >2.0 ppm

Copper (Cu): Occurs naturally in small amounts but may be present due to corroding copper pipes.

  • Acceptable range is <0.2 ppm
  • Problematic range is 0.2 -5.0 ppm
  • Severe problem range over >5.0 ppm
  • Toxicity in some plants has been shown with levels as low as 1.0 ppm.

Manganese (Mn): Dissolved from shale and sandstone, not usually a problem.

  • Acceptable range is <0.2 ppm
  • Problematic range is >0.2 ppm

Iron (Fe+2 or +3):  Iron is the 4th most abundant element in the earth’s crust.  Not easily absorbed by plants unless the pH of the water is less than 5.5.  Iron can mix with bacteria causing slimes which can clog irrigation equipment.

  • Acceptable range is <0.3 ppm
  • Problematic range is 0.3 -5.0 ppm
  • Severe problem range over >5.0 ppm
  • Levels greater than 5.0 ppm can form coatings on leaf surfaces reducing photosynthesis.

Sulfate (SO4-2): Naturally dissolved into water from rock and soil containing gypsum, iron sulfides, and other sulfur compounds. If mixed with calcium scale can form.

  • Acceptable range is <100 ppm
  • Problematic range is 100-200 ppm
  • Severe problem range over >200 ppm
  • Reverse Osmosis filtration is recommended course of action if levels are high.

Boron (B): Naturally occurring from ground water and decaying plant material.  Boron is required in small amounts, when in excess it is highly toxic.

  • Acceptable range is <1 ppm
  • Problematic range is 1.0-2.0 ppm
  • Severe problem range over >2.0 ppm

Sodium (Na+): Naturally occurring from dissolved minerals but also from road-salt & fertilizer.  Levels Greater than 70 ppm can cause foliar damage (leaf burn.)

  • Acceptable range is <70 ppm
  • Problematic range is 70-200 ppm
  • Severe problem range over >200 ppm

 Chloride (Cl-): Naturally occurs from dissolved minerals and sea water, but also may come from road-salt, fertilizer, and sewage.  Levels Greater than 100 ppm can cause foliar damage (leaf burn.)  Chloride can be absorbed by plant roots accumulating in leaves causing toxicity.

  • Acceptable range is <70 ppm
  • Problematic range is 70-300 ppm
  • Severe problem range over >300 ppm

 Nitrate (NO3-N): Naturally occurring in soil and from decaying plant material, high levels are often the result of fertilizer usage.  High concentrations can cause plant tissue to become more susceptible to pests.

  • Acceptable range is <50 ppm
  • Problematic range is 50-100 ppm
  • Severe problem range over >100 ppm

Chloramines in Your Drinking Water: The EPA does a Q&A

As discussed in my earlier blog, Chloramines are disinfectants used to treat drinking water. Chloramines have been proven to damage garden crops.  Chloramines are most commonly formed when ammonia is added to chlorine to treat drinking water. One in five American homes has water treated with chloramines.  My ongoing blog series discussing water quality has been a hit, but if you want more information specifically regarding Chloramines see what the EPA has to say about them.  Remember Chloramines can be removed with a simple reverse osmosis filter and KDF carbon filter.

Water Quality: Just Because It’s Clear Doesn’t Mean It’s Clean!

Reasons to but an RO Water Filter

Do You Want to Drink this Water? Niether do Your Plants.

On a hot summer day after working in your garden you might reach for an icy cold glass of water; that clear refreshing beverage we all take for granted is the life blood of our planet.  It sustains us, our plants and in turn the entire global ecosystem.  If you grabbed for a drink of water and it smelled bad, was dirty brown, or tasted funny you wouldn’t drink it; would you?  Most of us would either buy a water filter (like a reverse osmosis system) or bottled water because the thought of drinking a glass of brown dirty water is revolting.  So why would you feed it to your plants?

Too often I help people only concerned with their water quality after their gardens have shown serious problems.  As long as the water is clear and doesn’t smell bad most people give little thought to the water that comes out of their faucets or hoses.  There can be bacteria in the water, high chlorine levels, or even dangerous levels of salts or chemicals.  All of these are good reasons to be proactive and learn a bit about you water quality before there is an issue.

It can be as simple as a phone call to your local Department of Water Shed Management.  Often they will come to your home and test your water for chlorine levels, contaminants, and bacteria (for free.)  Now the bacteria they test for are typically the types which are harmful to people but the chlorine content and information about contaminants are useful to us as gardeners.

Here in AtlantaI did as I am suggesting you do.  I contacted the Atlanta Department of Watershed Management.  They were helpful, and provided fast service at no charge.  Within 1 week I had documented lab results stating that there was no Coli Form bacteria present in my water, No E Coli, and a Chlorine level of 0.7 PPM.  An acceptable amount of Chlorine for most plants is less than 140 PPM, but many plants such as orchids are much more sensitive to Chlorine and will tolerate almost none.

The Department of Water Shed Management was also kind enough to supply me with the official 2010 City ofAtlanta Water Quality Report.  This provided me with a few more pieces of useful information.  My water contained:

  • 0.6 PPM of Nitrate Nitrogen of which there should be less than 10 PPM (mostly from fertilizer run off entering our water system)
  • 0.12 PPM Copper of which there should be less than 0.2 PPM
  • 0.93 PPM Fluoride of which there should be less than 1.0 PPM

    Stealth Ro 200 GPD

    A RO System Like this Transforms Bad Water into Clear Water

Lastly a phone call to a supervisor provided me with a piece of information that was extremely important; Atlanta’s water supply is not treated with any kind of Chloramine, only Sodium Hypochlorite.  This meant that the purchase of aspecialty KDF activated carbon filter (to remove Chloramines) would not be necessary to make the water safe for my collection of orchids.  Chloramines unlike Chlorine can not be removed by a typical water filter or even a standard R/O system; they require a KDF style activated carbon filter to remove them.  Checking if your water department uses Chloramines is something all of us need to do; exposure to Chloramines for as little as 1 hour significantly inhibit plant growth according to recent scientific studies.  Check with your local water department to learn more about what is in your water.  Also check out my next blog to learn how to decipher a water report.