CHAPTER II
REVIEW OF RELATED LITERATURE AND STUDIES
NAWASA (National Water and Sewerage Authority) was established to provide
affordable potable or tap water for those who cannot afford bottled water. That is why
NAWASA needs a good and reliable source of potable water which is freshwater sources.
Freshwater is only 3% of earth’s water reservoir while the remaining 97% are
seawaters. Freshwaters are commonly potable except for those in glaciers and ice sheets
because of its solid form (Tarbuck and Lutgens, 2005).
Groundwater is usually good for drinking because it is buried underground which
causes water to be filtered as it passes through the rocks and roots of the trees.
Groundwater is stored in, and moves slowly through, moderately to highly permeable
rocks called aquifers. An aquifer may be a layer of gravel or sand, a layer of sandstone or
cavernous limestone. In terms of storage at any one instant in time; groundwater is the
largest single supply of fresh water available for use by humans. Wells pump
groundwater from the aquifer and then pipes deliver the water to cities, houses in the
country, or to crops (“The Ground Water Foundation”, 2011).
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Figure 1. The Groundwater Process
There are two types of aquifers, the unconfined and confined aquifers.
Unconfined aquifers are usually called phreatic aquifer, because as can be seen in the
illustration the water table or phreatic surface is its upper boundary. An unconfined
aquifer is one that is open to receive water from the surface, and whose water table
surface is free to fluctuate up and down, depending on the recharge/discharge rate. There
are no overlying "confining beds" of low permeability to physically isolate the
groundwater system. Confined aquifers are water that are overlain by impermeable rocks
and does not transmit any water at all (“Aquifer”, 2012).
A spring is a flowing groundwater above the surface. It is caused by large cracks,
cavities and tunnels through which groundwater flows, namely any natural occurrence
where water flows to the surface of the earth from below the surface. Thus it is where
the aquifer surface meets the ground surface. Springs occur when water pressure causes a
natural flow of groundwater onto the earth's surface. As rain filters down into the aquifer
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system, natural acids in the rainwater slowly dissolve the aquifer's limestone. Usually
most of the springs are potable depending on its qualities such as its pH, TDS, toxicity
and turbidity (Suwannee River Water Management District, 2006).
Table 1. Standard Parameters and Values for Drinking Water Source Quality
Water Characteristics
Minimum Acceptable
Maximum Allowable
Color
0
5
pH
6.5
8.5
Total Dissolved Solids
(mg/L)
Turbidity
0
500
0
5
Water Pressure (Psi)
60
80
Table 1 shows some of the standard water quality ranges for a water source to be
considered a feasible water source for Iligan City NAWASA.
In Chemistry, pH level is the measure of acidity of a liquid solution. Pure water is
said to be neutral thus the litmus paper maintains it color. Liquid solutions with a pH
level below 7 is said to be acidic so it turns blue litmus paper into red. For those pH
levels above 7, they are said to be alkaline or basic so it turns red litmus paper into blue
(“We find Water”, 2011).
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Figure 2. Litmus Paper as an Acid-Base Indicator
It is essential for potable water to be neutral because pH level affects the rate of
biochemical reactions. Higher pH makes ammonia compounds more toxic on the other
hand, lower ph enables dissolving of heavy metals if present in the water. Higher pH
increase respiratory deficiency. Lower pH generally indicates lower mineral
concentrations (TDS) (Ra Londe, 2006). Fresh water sources with a pH 5.5 or above 9.5
may not be able to sustain plant or animal species (Steven Institute and Technology,
2009).
As shown in Figure 1, the standard pH level for the Iligan City NAWASA, the
standard pH level for water source ranges from a minimum acceptable pH value of 6.5 to
a maximum allowable with a pH level of 8.5.
Another important characteristic of potable water is turbidity. Turbidity is a
principal physical characteristic of water and is an expression of the optical property that
causes light to be scattered and absorbed by particles and molecules rather than
transmitted in straight lines through a water sample. It is caused by suspended matter or
impurities that interfere with the clarity of the water. These impurities may include clay,
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silt, finely divided inorganic and organic matter, soluble colored organic compounds, and
plankton and other microscopic organisms. Simply stated, turbidity is the measure of
relative clarity of a liquid. Clarity is important when producing drinking water for human
consumption and in many manufacturing uses. Once considered as a mostly aesthetic
characteristic of drinking water, significant evidence exists that controlling turbidity is a
competent safeguard against pathogens in drinking water. (Science Fair Water, 2011)
Water turbidity causes a reduction in the depth of light penetration into the water
column. This effectively decreases rates of photosynthetic activity thus primary
productivity in submerged plants (a basic food source for aquatic animals). A reduction in
the food source at the primary level may then have a knock-on effect upon higher trophic
levels. High turbidity levels can also cause physical damage to leaf surfaces by abrasion
and by smothering (Science Fair Water, 2011).
High turbidity levels can adversely affect invertebrate populations; interfere with
the behavior, feeding and growth of salmanoids and other fish species. It can also cause
damage to fish gills by abrasion (hyperplasia), and cloning. High suspended sediment
concentrations may also increase the susceptibility of fish to disease. Mucus secreted by
fish in response to high concentrations of suspended solids attracts bacteria and fungus.
Turbidity can increase surface water temperature and lead to thermal stratification, a
problem not only in rivers, but also for downstream reservoirs such as groundwater and
lakes (Brondson and Clark, 2008).
To test turbidity, one can perform the secchi disk test. Secchi disk is created by
Fr. Prieto Angelo Secchi, an astrophysicist (Bungco and Marcela, 2011).
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Secchi
disk
is
a
circular
disk
used
to
measure
water transparency in oceans and lakes. It is used to measure the clarity of the water or
also known as its turbidity. The disc is mounted on a pole or line, and lowered slowly
down in the water. The depth at which the pattern on the disk is no longer visible is taken
as a measure of the transparency of the water. The unit for the turbidity used in this study
is the NTU (Nephelometric Turbidity Units).
The standard turbidity for drinking water ranges a minimum acceptable value of 0
NTU to a maximum allowable value of 5 NTU.
Figure 3. Secchi Disk
“Experiments have shown that the limit of visibility may be determined most
accurately by using a disc about 8 inches in diameter, divided into quadrants painted
alternately black and white like the target of a level-rod, and looking vertically down
upon it through a water-telescope provided with a suitable sunshade” (Wilson, 2005).
Total Dissolved Solids (TDS) is the total amount of mobile charged ions,
including minerals, salts or metals dissolved in a given volume of water, expressed in
units of mg per unit volume of water (mg/L), also referred to as parts per million (ppm).
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TDS is directly related to the purity of water and the quality of water purification systems
and affects everything that consumes, lives in, or uses water, whether organic or
inorganic, whether for better or for worse.
Figure 4. Total Dissolved Solids Scale
The chart values in Figure 4 represent national U.S. averages. Actual TDS levels
for geographic regions within the U.S. and other countries may vary. (HM Digital, 2008)
Dissolved solids refer to any minerals, salts, metals, cations or anions dissolved in
water. This includes anything present in water other than the pure water (H20) molecule
and suspended solids. Water may also pick up metals such as lead or copper as they
travel through pipes used to distribute water to consumers (WaterFiltersOnline, 2011).
Based on the interview conducted by the researchers to the Iligan City NAWASA
to determine the standard pH level for the Iligan City NAWASA, the standard TDS level
for a drinking water source ranges from a minimum acceptable value of 0 mg/L to a
maximum allowable value of 500 mg/L.
Toxicity is the degree to which a substance can harm humans or animals. Toxic
substances may affect any kind of water source including groundwater. Pollutants can
seep into groundwater supplies. Pollutants that contaminate surface water could also
contaminate groundwater. Compounds from the surface can move through the soil and
end up in the groundwater. For example, pesticides and fertilizers can find their way into
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groundwater supplies over time. Road salt, toxic substances from mining sites, and used
motor oil may also seep into groundwater. In addition, it is possible for untreated waste
from septic tanks and toxic chemicals from underground storage tanks to contaminate
groundwater (“Toxicity”, 2008).
Toxicity can refer to the effect on a whole organism, such as an animal, bacterium
or plant, as well as the effect on a substructure of the organism, such as a cell
(cytotoxicity) or an organ (organotoxicity). By extension, the word may be
metaphorically used to describe toxic effects on larger and more complex groups, such as
the family unit or society at large (Elano, 2003).
Based on an interview to the Iligan City NAWASA, Multiple Tube Fermentation
Technique is a method used to test the toxicity of a water sample. The allowable limit or
the most probable number of coli form in a 100 mL water to consider it non-toxic is <1.1.
Water pressure is also one of the standards used in determining whether a water
source is a potential water source for Iligan City NAWASA. Water pressure proves if the
water source can supply the residential houses. Water pressure is the amount of force
exerted by the water on the container. Water pressure affects the rate of water flow. If
water pressure is increased, the rate of water flow also increases. (McGraw-Hill ACT,
2008) The SI unit of pressure is the Pascal (Pa), which is equal to one Newton of force
per square meter. Because p = F/A, all units of pressure represent some ratio of force to
surface area. The principle SI unit is called a Pascal (Pa), or 1 N/m2. A Newton (N), the
SI unit of force, is equal to the force required to accelerate 1 kilogram of mass at a rate of
1 meter per second squared. Thus, a Pascal is equal to the pressure of 1 Newton over a
surface area of 1 m2 (InspectAPedia, 2012).
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As water flows to the house, the water loses some of its pressure to friction inside
of the pipe. The further the flow of the water, the more pressure it loses this leads to low
water pressure. A water source having a low water pressure is insufficient in supplying
the needs of residential houses. A water pressure booster is used to keep the water
pressure constant. A water pressure booster system is also an efficient way to provide
constant water pressure in the water mains (American Tank Company, 2012).
As mentioned by the Laboratory Technician of NAWASA, which is Ms. Maricar
V. Lagus, a common drinking water source that wishes to provide water to a residential
area must have a water pressure ranging from minimum acceptable value of 60 Psi to a
maximum allowable value of 80 Psi.
Another indicator used to determine the feasibility of a drinking water are the
indicators of water contamination which are the Total coli form, fecal coli form, and E.
coli. The total coli form group is a large collection of different kinds of bacteria. Fecal
coli forms are types of total coli form that mostly exist in feces. E. coli is a sub-group of
fecal coli form. When a water sample is sent to a lab, it is tested for total coli form. If
total coli form is present in the water, the sample will also be tested for either fecal coli
form or E. coli.
Total coli form bacteria are commonly found in the environment. If water is tested
and the results show that only total coli form bacteria are detected in drinking water, the
source is probably environmental. Fecal contamination is not likely. However, if
environmental contamination can enter the system, there may also be a way for pathogens
to enter the system. Therefore, it is important to find the source and resolve the problem.
When coli form bacteria are found, it is necessary to investigate the reason on how the
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contaminants moved to the water. Taking repeat samples helps determine whether an
actual problem exists in the system. If any of the repeat samples detect coli form bacteria,
the initial findings are considered confirmed. If total coli form bacteria are confirmed in
the drinking water, the water system should be inspected. Once the source is identified, it
can usually be resolved by making system repairs, flushing, and adding chlorine for a
short period of time. Confirmation of fecal coli forms bacteria or E. coli in a water system
indicates recent fecal contamination, which may pose an immediate health risk to anyone
consuming the water (Department of Health-United States of America, 2010).
Tabudlong (2002) studies an investigated one of the three properties in her
research about groundwater in Emerald Homes, the bacteriological properties. The
researcher collected the water samples from her home and sampling was also done in the
laboratory. The results of these experiments may vary. In the bacteriological analysis,
both the samples has 5/5 coli form count after the presumptive and confirmatory test and
also had a Most Probable Number (MPN) of less than 16. The MPN in E. Coli medium in
sample1 was 22 while sample 2 is less than 22. It was discovered and confirmed that
there are typical colonies of less harmful bacteria found in both samples and sample 1
had the MPN of colony count.
Buna (2004) studied on the bacteriological analysis of three water sample sources;
the deep well, tap water and bottled water. The researcher collected samples in the
Hinaplanon since there is pump which supplies deep well water, from the residential who
use tap water, in NAWASA and from Coastal Waters, an Iligan-Based bottled water. The
results showed that deep-well water has the most number of coli form while tap water has
the least number of coli form count.