Sources of Garden Water

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Sources of Garden Water

• Primary Sources
• Private well or spring
• Public water supplies
• Alternative Sources
• Rainfall harvesting (roof water)
• Gray water (wastewater)
• Ponds
• Pools/hot tubs

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Water Standards and Measures

• Drinking water standards acceptable level
• Primary - health based (bacteria, lead,
  pesticides, etc.)
• Secondary - aesthetic (iron, chloride, manganese,
  etc.)
• Units
• mg/L ppm
• µg/L ppb
• special units (bacteria, pH, etc.)

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Public Water Supply

• Routinely tested
• Primary concerns
• Softening
• Chlorine residual

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Chlorine

• Symptom burning of leaf tips or margins,
  bronzing, premature yellowing and loss of leaves
• Aquatic plants most sensitive (5 mg/L)
• As little as 7 mg/L can cause injury to some
  sensitive garden plants
• Many plants can handle up to 50 mg/L
• Chlorine residual in drinking water usually 0.2
  to 0.5 mg/L
• Superchlorination 3 to 5 mg/L
• More of a problem with use of pool or spa water

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Hardness

• Calcium and magnesium
• Causes whitish deposit on leaf
• Usually noticed around 100 mg/L hardness
• May clog drip or spray irrigation devices
• Removed through softening

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Schematic of Softener
Water Softening
Ion Exchange Sodium for Calcium Magnesium
Raw Water
Calcium Magnesium
RESIN (Sodium)
Treated Water
(Sodium)
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Schematic 2 of Softener
Recharge with Brine
Calcium Magnesium
Waste Water
RESIN (Calcium Magnesium)
Brine
(Sodium)
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Sodium

• From softened water, road salt, deep wells
• Reduces soil permeability, increases pH
• May directly affect plant
• Levels of concern
• lt70 mg/L - no concern (lt150 mg/L hardness)
• 70-180 - moderate (150-360 mg/L hardness)
• 180-200 - severe (360-400 mg/L hardness)
• gt200 very severe (gt400 mg/L hardness)

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What to Do?

• ONLY SOFTEN HOT WATER !
• Use potassium salt instead of sodium

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Softener Backwash Waste

• Very high chloride concentration in excess of
  10,000 mg/L
• Extremely toxic to all plants
• Should go directly to septic systems (does not
  cause problems with septic system)
• Widespread softener use may increase chlorides in
  groundwater

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Private Water Supplies
Wells drilled between 1966-1994

• Over one million systems
• No regulations
• Potential problems
• Bacteria
• Hardness and softening
• Iron
• Chloride (sodium?)
• Sulfate

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Bacteria

• Coliform bacteria
• Broad group of many "indicator" bacteria
• E. coli bacteria
• Come from human or animal waste
• Much more serious
• Carefully rinse edible portion of plant

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Shock Chlorination

• Use very high dose of chlorine (gt100 mg/L) to
  kill existing bacteria in well
• Run water to waste after
• about six hours
• BE CAREFUL WHERE YOU
• DISCHARGE THIS WATER

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Chloride

• Not related to chlorine
• Most troublesome anion for plants
• Usually more toxic than sulfate
• Tolerance varies among plants
• Most sensitive 100 mg/L
• 250-500 often affects plants
• Sources - gas wells, very deep wells, road salt,
  softener brine
• Sodium often accompanies it

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Iron and Sulfate

• Most likely in coal mining areas
• Iron may come from bottom of ponds
• Iron above 0.3 mg/L may clog watering devices and
  leave red deposit on plants
• Iron bacteria may clog watering devices
• Sulfate gt 600 mg/L may harm plants

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How Common are Problems in PA ?
of wells and springs that exceed standard
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Protecting Wells and Springs

• Slope ground away from water source to prevent
  surface contamination
• Control and/or carefully monitor activities close
  to water source (especially upslope)
• Keep herbicides and other chemicals at least 50
  feet from well or spring

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Pay Attention to Land Use
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Test the Water!

• Use certified laboratories
• Good general tests
• Coliform bacteria - absent
• pH - around 7.0 ideal
• Specific conductance - gt2,000 µS/cm may indicate
  salt or other problem
• Iron - gt 0.3 mg/L may cause red stains
• Chloride - gt250 mg/L affects some plants
• Sodium - gt70 mg/L may be problematic
• Sulfate - gt900 mg/L problematic (mining)

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Drought Emergency

• Restrictions on non-essential water use (mostly
  outside use)
• Applies to public and private water supplies
• Causes utilization of alternative water sources

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Rain Harvesting for Garden Watering
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Rainwater Harvesting

• Similar to rainfall - very dilute
• Concentrate atmospheric pollutants
• Sulfate
• Nitrate
• Mercury, etc.
• Some hydrocarbons from roofing material
• Concentrations related to time between storms

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Soil Acidification
H
NO3-
SO42-
Base cations (Ca, Mg, K, Na) become depleted,
initial amount important
Aluminum common in soil but does not become
mobile until soil acidifies, toxic to plants.
Measure soil pH to determine risk.
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Gray Water

• Non-toilet wastewater
• Bathtubs, showers, sinks
• Washing machines
• dishwashers
• Pollutants
• Grease, hair, detergents, cosmetics, food, fecal
  matter?
• Use is limited (legally) because it must enter an
  approved treatment system
• Not enforced

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Gray Water

• Use as little as possible
• Rule-of-thumb
• Half gallon per square foot per week
• Order of preference
• Shower/bath
• Bathroom sink
• Utility sink
• Washing machine - avoid diaper washing
• Kitchen sink - too much food, grease
• Dishwasher - too much food, grease

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Applying Gray Water

• Use on shrubs and ornamentals first, garden last
• Do not apply to leafy vegetables or root crops
• Apply directly to soil surface - do not use
  sprinklers
• Do not drip irrigate - may clog
• Avoid steep slopes
• Apply over broad area and rotate

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Applying Gray Water

• Apply thick compost mulch to speed decomposition
  of wastes
• Use only on established plants - seedlings
  sensitive to impurities
• Do not use on acid loving plants

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What About Soap/Detergents?

• Biodegradable
• Phosphates may be good for plants
• Can be problematic over extended time
• Main problem sodium salts
• Damage soil structure
• Create alkaline conditions
• Damage plants

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What About Soap/Detergents?

• Avoid using bleach
• Avoid detergents with boron (very toxic)
• Use ammonia rather than chlorine for household
  cleaning
• Avoid detergents with "softening power"
• Excessive sodium salts

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Protecting the Soil

• Test soil pH
• Sodium loaded will be above 7.5
• Spread 2 lbs/100 ft2 of gypsum (calcium sulfate)
  once per month
• Rotate to rainfall or fresh water to dilute

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Gray Water Pathogens

• Possible in bath, shower or washing machine water
• Die quickly
• Absorbed by organic matter
• If used on garden, wash edible portions carefully

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Ponds

• Irrigation Problems
• Aquatic herbicides
• Iron/manganese
• pH, hardness
• Bacteria

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Pools and Hot Tubs
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Pools and Hot Tubs

• Variety of chemicals
• Oxidizers (chlorine, bromine)
• Algicides
• pH adjusters
• Metals binders
• Many more!

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Pools and Hot Tubs

• Generally not recommended for plants
• Allow to sit in bucket to dissipate chemicals
• Usability related to amount of chemicals and time
  since chemicals were applied
• Bromine
• Levels up to 100 mg/L generally not toxic to
  plants
• Chlorine
• Concentration may be 5-10 mg/L
• Dissipates quickly

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Penn State Water Quality Web Site
www.sfr.cas.psu.edu/water