Landscape
Guide: Water Characteristics
Introduction
| Water Characteristics
| Soil Management |
Irrigation |
Turf Grass | Water Features
| Plant List
How Recycled Water is Produced
Recycled water (which is also referred to as "reclaimed
water") is created from wastewater. In our area, wastewater is processed
and treated at the San Jose/Santa Clara Water Pollution Control Plant,
one of the largest such treatment plants in California.
After entering the plant, wastewater from homes and
businesses undergoes a carefully regulated purification and disinfection
process. Throughout the process, samples are taken and tested in a state-of-the
art laboratory to ensure high-quality water.
Recycled water is analyzed frequently to assure its
horticultural suitability and it is of such exceptional quality that it
meets or exceeds most drinking water standards. Water quality standards
are listed on the chart that follows. More detailed information can be
provided to you that compares well water, treated water, and Hetch Hetchy
with South Bay recycled water.
Chemical Characteristics of Recycled Water
The following information provides some specifics about
the chemistry of recycled water. With a few exceptions, recycled water
is very similar to drinking or potable water.
Alkalinity
Recycled water is well within the range of drinking water standards
for alkalinity. With all landscaping, pH should be regularly monitored.
Sodium
Individual plant species vary greatly in their sensitivity
to sodium. The symptoms of sodium injury include a marginal scorch on
the edges of older leaves. This is the effect of the plant's taking
up sodium from the soil water. As water transpires from the leaf surface,
sodium accumulates in the tissue. With overhead irrigation, sodium can
be directly absorbed and can accumulate in wet leaves, thereby causing
leaf burn. Soil surface irrigation lessens this problem.
Chloride
Woody plants are especially sensitive to chloride. Evidence
of chloride toxicity is first seen as leaf burn that starts at the tips
of older leaves and progresses back into the leaf blade. Using a soil-applied
watering system will significantly lessen any problems.
Boron
A constituent of almost all natural water, boron is essential
to plant growth. The boron level of recycled water meets drinking water
standards for safety. High levels of boron can be identified by yellowing,
marginal burning and internal spotting.
Nitrogen
Because recycled water provides nitrogen in quantities that
significantly benefit landscaping and turf, use of this water can reduce
the need for synthetic fertilizer, while cutting fertilizer costs.
Bicarbonate
Bicarbonate levels in recycled water are minimal. Higher levels
could cause white deposits on plant leaves. To avoid any problems, use
soil-applied watering.
Elements Important to Plants - Horticultural Water Quality
| Primary
Standard |
Symbol |
Unit of
Measurement |
Drinking
Water Standards |
SBWR Recycled
Water Constituents |
| Mandatory
Health Related |
| Clarity/Turbidity |
|
NTU |
0.5 |
<1.0 |
| Coliform Bacteria |
|
% Tests Positive |
<5.0 |
<2.0 |
| Inorganic Chemicals |
|
|
|
|
| Fluoride |
F |
mg/L |
1.4 – 2.4 |
0.46 |
| Nitrate |
NO3-N |
mg/L |
45 |
20.2 |
|
|
|
|
|
| Secondary Standard |
|
|
Aesthetic |
Horticultural |
| Apparent Color |
|
Units |
15 |
18 |
| Odor Threshold |
|
Units |
3 |
<5 |
| Alkalinity |
Total CaCO3 |
|
No Standard |
158.3 |
| Adj. Na Adsorption Ratio |
RNa |
mg/L |
No Standard |
4.42 |
| Hydrogen Ion Activity |
pH (6.5-8.4) |
Units |
No Standard |
8.3 |
| Equilibrium Reaction |
pHc |
Units |
No Standard |
7.44 |
| Electrical Conductivity |
ECw |
DS/m |
No Standard |
1.18 |
| Total Dissolved Solids |
TDS |
mg/L |
1,000 |
755 |
| Sodium |
Na |
mg/L |
No Standard |
140 |
| Sulfate |
SO4 |
mg/L |
500 |
124 |
| Iron |
Fe |
mg/L |
0.3 |
0.1 |
| Zinc |
Zn |
mg/L |
5 |
0.06 |
| Manganese |
Mn |
mg/L |
0.05 |
<0.02 |
| Boron |
B |
mg/L |
No Standard |
0.48 |
| Chloride |
CL |
mg/L |
500 |
148 |
|
|
|
|
|
| Nutrient Content = Pounds
per 1000 square feet per foot of Applied Water* |
| Nitrogen (Actual) |
N |
Lbs |
|
1.04 |
| Phosphorus |
P2O5 |
Lbs |
|
0.33 |
| Potassium |
K2O |
Lbs |
|
0.9 |
*Compared to a fertilizer program which
applies 25 pounds 21-7-14 annually, this water
would supply about 80% of the nitrogen and phosphorus and 107% of the
potassium.
|
