Water Test InterpretationWater Test InterpretationMike KizerMike Kizer

OSU Extension Irrigation SpecialistOSU Extension Irrigation Specialist

CaCa++++

NaNa++

ClCl--

SOSO44==

KK++

MgMg++++

HCOHCO33--

COCO33==

NONO33--

Measures of Water QualityMeasures of Water Quality

• Electrical Conductivity (EC)Electrical Conductivity (EC)

• Total Dissolved Solids (TDS)Total Dissolved Solids (TDS)

• Individual mineral concentrationsIndividual mineral concentrations

• Calculated salinity productsCalculated salinity products(Hardness, SAR, Na%, etc.)(Hardness, SAR, Na%, etc.)

Electrical ConductivityElectrical Conductivity(EC)(EC)

• Pure water is a poor conductor of electricityPure water is a poor conductor of electricity

• The more minerals dissolved in water, the The more minerals dissolved in water, the more current it conductsmore current it conducts

• EC is a good estimator of total mineral EC is a good estimator of total mineral content (TSS)content (TSS)

UnitsUnits - EC - EC

• mmho/cm = (millimho per centimeter)mmho/cm = (millimho per centimeter) mho/cm = (micromho per centimeter)mho/cm = (micromho per centimeter)• dS/m = (deciSiemen/meter)dS/m = (deciSiemen/meter)• mS/cm = (milliSiemen per centimeter)mS/cm = (milliSiemen per centimeter)

• 1 mmho/cm = 1 dS/m = 1mS/cm1 mmho/cm = 1 dS/m = 1mS/cm• 1 mmho/cm = 1000 1 mmho/cm = 1000 mho/cmmho/cm

Total Dissolved SolidsTotal Dissolved Solids(TDS)(TDS)

• TDS is calculated by totaling all measured TDS is calculated by totaling all measured mineral concentrations as determined by mineral concentrations as determined by chemical analyseschemical analyses

• TSS is an estimate of TDS based on ECTSS is an estimate of TDS based on EC

• EC (mmho/cm) x 640 EC (mmho/cm) x 640 TSS mg/l TSS mg/l• This equivalence is approximate andThis equivalence is approximate and

depends on the ions causing the salinitydepends on the ions causing the salinity

Units Units - TDS / TSS - TDS / TSS

mg/lmg/l = milligrams/liter = milligrams/liter ppmppm = parts per million = parts per million

g/lg/l = micrograms/liter = micrograms/liter ppbppb = parts per billion = parts per billion

• 1 mg/l = 1 ppm 1 mg/l = 1 ppm in water chemistryin water chemistry(1 liter of water weighs 1,000,000 mg)(1 liter of water weighs 1,000,000 mg)

• 1 mg/l = 1000 1 mg/l = 1000 g /lg /l• 1 1 g /l = 1 ppbg /l = 1 ppb in water chemistry in water chemistry

SW&FAL Water Quality TestsSW&FAL Water Quality Tests

The OSU Soil Water & Forage Analytical The OSU Soil Water & Forage Analytical Laboratory (Room 048 Ag. Hall) offers three Laboratory (Room 048 Ag. Hall) offers three water tests:water tests:

• Livestock Water TestLivestock Water Test

• Household Water TestHousehold Water Test

• Irrigation Water TestIrrigation Water Test(All tests require a (All tests require a 1 pint1 pint water sample) water sample)

Livestock Water TestLivestock Water Test

• Price:Price: $6.00$6.00

• Analytes:Analytes:• pHpH

• Total Soluble Salts (TSS)Total Soluble Salts (TSS)

• Electrical Conductivity (EC)Electrical Conductivity (EC)

• Nitrate-Nitrogen (NONitrate-Nitrogen (NO33-N)-N)

Livestock Water QualityLivestock Water QualityTotal Soluble Salts -Total Soluble Salts - TSSTSS

TSS (ppm)TSS (ppm) InterpretationInterpretation• Less than 1000: ExcellentLess than 1000: Excellent• 1000 – 3000:1000 – 3000: Satisfactory for all animals Satisfactory for all animals• 3000 – 5000:3000 – 5000: Unsatisfactory for poultry Unsatisfactory for poultry• 5000 – 7000:5000 – 7000: Can be used except for Can be used except for

pregnant, lactating or pregnant, lactating or immature livestock immature livestock

• Over 10,000:Over 10,000: Unsatisfactory for all animals Unsatisfactory for all animals

Livestock Water QualityLivestock Water QualityNitrate- Nitrogen –Nitrate- Nitrogen – NONO33-N-N

NONO33-N-N (ppm) (ppm) InterpretationInterpretation

• Less than 100:Less than 100: Satisfactory for all animals Satisfactory for all animals

• 100 – 290:100 – 290: Use with care when given in Use with care when given in combination with high nitrate combination with high nitrate feeds (especially certain feeds (especially certain forages in times of drought) forages in times of drought)

• Over 290:Over 290: Unsatisfactory for all animals Unsatisfactory for all animals

Livestock Water QualityLivestock Water Quality

• Sulfate (SOSulfate (SO44)) – If most of the TSS are sulfates the acceptable TSS If most of the TSS are sulfates the acceptable TSS

level is reduced because of scouring concernslevel is reduced because of scouring concerns– Polioencephalomalasia (PEM) is a nervous system Polioencephalomalasia (PEM) is a nervous system

disease in cattle caused by thiamine deficiency. disease in cattle caused by thiamine deficiency. High dietary sulfate has been linked to thiamine High dietary sulfate has been linked to thiamine deficiency by research and case studies.deficiency by research and case studies.

• pHpH– The preferred range is 6.0-8.5. Animals can The preferred range is 6.0-8.5. Animals can

tolerate water outside this range, but some species tolerate water outside this range, but some species may perform poorly.may perform poorly.

Household Water TestHousehold Water Test

• Price:Price: $15.00$15.00

• Analytes:Analytes:• Sodium (Na)Sodium (Na) Nitrate-Nitrogen (NONitrate-Nitrogen (NO33-N-N

• Calcium (Ca)Calcium (Ca) Iron (Fe)Iron (Fe)

• MagnesiumMagnesium (Mg)(Mg) Manganese (Mn)Manganese (Mn)

• Potassium (K)Potassium (K) ZnZn

• Boron (B)Boron (B) Electrical Conductivity (EC)Electrical Conductivity (EC)

• HardnessHardness Total soluble Salts (TSS)Total soluble Salts (TSS)

• Chloride (Cl)Chloride (Cl) Sodium PercentageSodium Percentage

• Sulfate (SOSulfate (SO44)) pHpH

Household Water TestHousehold Water TestNitrate-Nitrogen – Nitrate-Nitrogen – (NO(NO33-N)-N)

• NONO33-N is the only analyte on the test with a -N is the only analyte on the test with a

Federal SDWA Federal SDWA StandardStandard

• The NOThe NO33-N standard is 10 mg/l-N standard is 10 mg/l

• Newborn infants (less than 9 months) and Newborn infants (less than 9 months) and pregnant women are “at-risk” consumerspregnant women are “at-risk” consumers

• NONO33-N affects the blood’s ability to carry -N affects the blood’s ability to carry

oxygen, causing oxygen, causing methemoglobenemiamethemoglobenemia

Household Water TestHousehold Water TestSecondary ContaminantsSecondary Contaminants

• Other regulated analytes on the Household Other regulated analytes on the Household Water Test are Secondary Contaminants that Water Test are Secondary Contaminants that have Federal SDWA have Federal SDWA GuidelinesGuidelines

• Exceeding SDWA Guidelines is not a primary Exceeding SDWA Guidelines is not a primary health riskhealth risk

• Secondary contaminants affect aesthetic quality Secondary contaminants affect aesthetic quality of water (taste, odor, etc.) or damage the water of water (taste, odor, etc.) or damage the water system (hardness, corrosion, etc.)system (hardness, corrosion, etc.)

Household Water TestHousehold Water TestSecondary ContaminantsSecondary Contaminants

Secondary contaminants can indirectly affect Secondary contaminants can indirectly affect health:health:– High sulfatesHigh sulfates can cause diarrhea which could can cause diarrhea which could

result in dehydrationresult in dehydration– Corrosion due to Corrosion due to low pHlow pH and and low alkalinitylow alkalinity can can

leach lead and copper from plumbing fixtures leach lead and copper from plumbing fixtures which could cause lead toxicitywhich could cause lead toxicity

Corrosiveness of WaterCorrosiveness of WaterpH – Alkalinity BalancepH – Alkalinity Balance

4

5

6

7

8

9

10

0 100 200 300 400 500 600

Total Alkalinity, (mg/l CaCO3 equivalent)

pH

Deposition Zone

Corrosive Zone

Neutral Zone

Household Water TestHousehold Water TestHardnessHardness

Hardness ClassHardness Class CaCOCaCO33 Equivalent Equivalent

Hardness (mg/l)Hardness (mg/l)

SoftSoft 0 – 600 – 60

Moderately HardModerately Hard 60 – 12060 – 120

HardHard 120 – 180120 – 180

Very HardVery Hard 180 +180 +

Hardness is caused by calcium and magnesiumHardness is caused by calcium and magnesium (iron also contributes to hardness)(iron also contributes to hardness)

Irrigation Water TestIrrigation Water Test

• Price:Price:$15.00$15.00• Analytes:Analytes:

– Sodium (Na)Sodium (Na) —— Chloride (Cl)Chloride (Cl)– Calcium (Ca)Calcium (Ca) —— Sulfate (SO4)Sulfate (SO4)– Magnesium (Mg)Magnesium (Mg) —— Nitrate-Nitrogen (NONitrate-Nitrogen (NO33-N)-N)– Potassium (K)Potassium (K) —— Carbonate (COCarbonate (CO33))– Boron (B)Boron (B) —— Bicarbonate (HCOBicarbonate (HCO33))– pHpH —— Electrical Conductivity (EC)Electrical Conductivity (EC)– HardnessHardness —— Total Soluble Salts (TSS)Total Soluble Salts (TSS)– Residual Carbonates Residual Carbonates —— Sodium Adsorption Ratio Sodium Adsorption Ratio

(SAR)(SAR)

Irrigation Water QualityIrrigation Water Quality Important AnalytesImportant Analytes

•• EC (or TSS):EC (or TSS): determines soil osmotic potential determines soil osmotic potential

•• SAR (or Na%):SAR (or Na%): rates infiltration problem potential rates infiltration problem potential

•• Boron:Boron: toxic at very low concentrations toxic at very low concentrations

•• Residual Carbonates (RSC):Residual Carbonates (RSC): raises effective SAR/Na% raises effective SAR/Na%

The Effect of The Effect of Salinity of Soil Salinity of Soil

Water AvailabilityWater Availability

Salt ConcentrationsSalt Concentrations

0.4% = 4000 mg/l0.4% = 4000 mg/l

0.2% = 2000 mg/l0.2% = 2000 mg/l

0.1% = 1000 mg/l0.1% = 1000 mg/l

Irrigation Water QualityIrrigation Water QualitySodium (Na) HazardSodium (Na) Hazard

• Na generally creates soil infiltration problems Na generally creates soil infiltration problems before becoming toxic to plantsbefore becoming toxic to plants

• In hot, dry weather conditions sprinkling can lead In hot, dry weather conditions sprinkling can lead to leaf burning due to Na toxicityto leaf burning due to Na toxicity

• Na reduces soil permeability by dispersing clay Na reduces soil permeability by dispersing clay particles which seal larger pore spacesparticles which seal larger pore spaces

• Na hazard is greater high clay content soilsNa hazard is greater high clay content soils• Na hazard is greater in expanding clays than in Na hazard is greater in expanding clays than in

non-expanding claysnon-expanding clays

Potential for infiltration problems due to high NaPotential for infiltration problems due to high Na++ water. water.

Water Suitability Based on Total Salinity and Sodium ContentWater Suitability Based on Total Salinity and Sodium Content

(Example: EC = 1.7 dS/m = 1700 (Example: EC = 1.7 dS/m = 1700 mho/cm and Na%= 35)mho/cm and Na%= 35)

Irrigation Water QualityIrrigation Water QualityBoron (B)Boron (B)

• Crops are very sensitive to boronCrops are very sensitive to boron

• Threshold soil concentration for yield Threshold soil concentration for yield reduction: reduction: 0.3 – 5 mg/l0.3 – 5 mg/l

• Toxic to all vegetation: Toxic to all vegetation: 10-15 mg/l10-15 mg/l

• Typical boron toxicity symptoms are spotting, Typical boron toxicity symptoms are spotting, yellowing and/or drying at tips and edges of yellowing and/or drying at tips and edges of older leavesolder leaves

Irrigation Water QualityIrrigation Water QualityResidual Carbonates (RSC)Residual Carbonates (RSC)

• Excessive bicarbonate and carbonate in irrigation Excessive bicarbonate and carbonate in irrigation water will combine with calcium and magnesium water will combine with calcium and magnesium ions in soilions in soil

• This effectively increases the SAR and leads to This effectively increases the SAR and leads to greater risk of infiltration problemsgreater risk of infiltration problems

• Residual carbonates Residual carbonates ≥ ≥ 2.5 are usually a problem2.5 are usually a problem

RSC = (CORSC = (CO33 + HCO + HCO33) ) -- (Ca + Mg) (Ca + Mg)

Nitrate NitrogenNitrate Nitrogen

• NONO33-N in irrigation water should be -N in irrigation water should be

accounted for in nutrient managementaccounted for in nutrient management

• 1 mg/L of NO1 mg/L of NO33-N in irrigation water -N in irrigation water

applies 0.23 lb/acre of N per 1 inch of applies 0.23 lb/acre of N per 1 inch of irrigation water appliedirrigation water applied

Water Quality Units and TermsWater Quality Units and Terms(Concentrations)(Concentrations)

1 mg/l = 1 ppm = 1000 1 mg/l = 1 ppm = 1000 g/lg/l = 1000 ppbppb

TSS = Total Soluble SaltsTSS = Total Soluble Salts

TDS = Total Dissolved SolidsTDS = Total Dissolved Solids

TSS TSS TDS TDS

TSS, (mg/l) TSS, (mg/l) 640 x EC, (mmho/cm) 640 x EC, (mmho/cm)

(Electrical Conductivity)(Electrical Conductivity)

1 mmho/cm = 1 dS/m = 1 mS/cm1 mmho/cm = 1 dS/m = 1 mS/cm = 1000 = 1000 mho/cmmho/cm

EC = electrical conductivity of waterEC = electrical conductivity of water

ECECee = electrical conductivity of saturated soil extract = electrical conductivity of saturated soil extract

Water Quality Units and TermsWater Quality Units and Terms(Concentrations)(Concentrations)

meq/l = milliequivalents per litermeq/l = milliequivalents per liter

epm = equivalents per millionepm = equivalents per million

1 meq/l = 1 epm1 meq/l = 1 epm

IonIon ppm per meq/lppm per meq/l IonIon ppm per meq/lppm per meq/l

CaCa 20 20 COCO33 30 30

MgMg 12 12 HCOHCO33 61 61

NaNa 23 23 SOSO44 48 48

KK 39 39 ClCl 35.5 35.5

Derived Water Quality TermsDerived Water Quality Terms

SAR = SAR = Sodium Adsorption RatioSodium Adsorption Ratio

SAR = Na (Ca+Mg)/2SAR = Na (Ca+Mg)/2

Na% = Na% = Sodium PercentageSodium Percentage

Na% = (Na x 100) (Ca+Mg+K+Na)Na% = (Na x 100) (Ca+Mg+K+Na)

RSC = RSC = Residual Sodium CarbonatesResidual Sodium Carbonates

RSC = (CORSC = (CO33 + HCO + HCO33) ) -- (Ca + Mg) (Ca + Mg)

(the 3 calculations on this page are in (the 3 calculations on this page are in meq/lmeq/l))

OSU PublicationsOSU Publications

• L-256 L-256 Understanding Your Livestock Understanding Your Livestock Water Test Report Water Test Report

• L-296L-296 Understanding Your Household Understanding Your Household Water Test Report Water Test Report

• L-323L-323 Understanding Your Irrigation Understanding Your Irrigation Water Test Report Water Test Report

• F-2401F-2401 Classification of Irrigation Water Classification of Irrigation Water Quality Quality

To download a copy of this presentation go to:To download a copy of this presentation go to:

(http://biosystems.okstate.edu/Home/mkizer/index.htm)(http://biosystems.okstate.edu/Home/mkizer/index.htm)