*3.1.3 Color*

Materials decayed from organic matter, namely, vegetation and inorganic matter such as soil, stones, and rocks impart color to water, which is objectionable for esthetic reasons, not for health reasons [10, 20].

Color is measured by comparing the water sample with standard color solutions or colored glass disks [10]. One color unit is equivalent to the color produced by a 1 mg/L solution of platinum (potassium chloroplatinate (K2PtCl6)) [10].

The color of a water sample can be reported as follows:


Color is graded on scale of 0 (clear) to 70 color units. Pure water is colorless, which is equivalent to 0 color units [10].

### *3.1.4 Taste and odor*

Taste and odor in water can be caused by foreign matter such as organic materials, inorganic compounds, or dissolved gasses [19]. These materials may come from natural, domestic, or agricultural sources [21].

The numerical value of odor or taste is determined quantitatively by measuring a volume of sample A and diluting it with a volume of sample B of an odor-free distilled water so that the odor of the resulting mixture is just detectable at a total mixture volume of 200 ml [19, 22]. The unit of odor or taste is expressed in terms of a threshold number as follows:

$$\mathbf{TON} \text{ or } \mathbf{TTN} = (\mathbf{A} + \mathbf{B})/\mathbf{A} \tag{1}$$

where TON is the threshold odor number and TTN is the threshold taste number.

#### *3.1.5 Solids*

Solids occur in water either in solution or in suspension [22]. These two types of solids can be identified by using a glass fiber filter that the water sample passes through [22]. By definition, the suspended solids are retained on the top of the filter and the dissolved solids pass through the filter with the water [10].

If the filtered portion of the water sample is placed in a small dish and then evaporated, the solids as a residue. This material is usually called total dissolved solids or TDS [10].

Total solid (TS) = Total dissolved solid (TDS) + Total suspended solid (TSS) (2)

Water can be classified by the amount of TDS per liter as follows:


The residue of TSS and TDS after heating to dryness for a defined period of time and at a specific temperature is defined as fixed solids. Volatile solids are those solids lost on ignition (heating to 550°C) [10].

These measures are helpful to the operators of the wastewater treatment plant because they roughly approximate the amount of organic matter existing in the total solids of wastewater, activated sludge, and industrial wastes [1, 22]. **Figure 1** describes the interrelationship of solids found in water [22]. They are calculated as follows [10]:

• Total solids:

$$\text{Total solids (mg/L)} = \left[ \left( \text{TSA} - \text{TSB} \right) \right] \times 1000 \text{/sample (mL)} \tag{3}$$

**7**

*Water Quality Parameters*

• Total dissolved solids:

*Interrelationship of solids found in water [22].*

• Total suspended solids:

of dish and filter paper in milligram.

• Fixed and volatile suspended solids:

of dish in milligrams.

**Figure 1.**

Total dissolved solids (mg/L) = [(TDSA – TDSB)] × 1000/sample (mL) (4)

where TDSA = weight of dried residue + dish in milligrams and TDSB = weight

Total suspended solids (mg/L) = [(TSSA – TSSB)] × 1000/sample (mL) (5)

where TSSA = weight of dish and filter paper + dried residue and TSSB = weight

Volatile suspended solids (mg/L) = [(VSSA – VSSB)] × 1000/sample (mL) (6)

where VSSA = weight of residue + dish and filter before ignition, mg and

VSSB = weight of residue + dish and filter after ignition, mg.

*DOI: http://dx.doi.org/10.5772/intechopen.89657*

where TSA = weight of dried residue + dish in milligrams and TSB = weight of dish in milligrams.

*Water Quality Parameters DOI: http://dx.doi.org/10.5772/intechopen.89657*

*Water Quality - Science, Assessments and Policy*

which is equivalent to 0 color units [10].

natural, domestic, or agricultural sources [21].

*3.1.4 Taste and odor*

*3.1.5 Solids*

solids or TDS [10].

• Total solids:

dish in milligrams.

• freshwater: <1500 mg/L TDS;

• saline water: >5000 mg/L TDS.

• brackish water: 1500–5000 mg/L TDS;

solids lost on ignition (heating to 550°C) [10].

a threshold number as follows:

Color is graded on scale of 0 (clear) to 70 color units. Pure water is colorless,

Taste and odor in water can be caused by foreign matter such as organic materials, inorganic compounds, or dissolved gasses [19]. These materials may come from

The numerical value of odor or taste is determined quantitatively by measuring a volume of sample A and diluting it with a volume of sample B of an odor-free distilled water so that the odor of the resulting mixture is just detectable at a total mixture volume of 200 ml [19, 22]. The unit of odor or taste is expressed in terms of

where TON is the threshold odor number and TTN is the threshold taste number.

Solids occur in water either in solution or in suspension [22]. These two types of solids can be identified by using a glass fiber filter that the water sample passes through [22]. By definition, the suspended solids are retained on the top of the filter

If the filtered portion of the water sample is placed in a small dish and then evaporated, the solids as a residue. This material is usually called total dissolved

Total solid (TS) = Total dissolved solid (TDS) + Total suspended solid (TSS) (2)

The residue of TSS and TDS after heating to dryness for a defined period of time and at a specific temperature is defined as fixed solids. Volatile solids are those

These measures are helpful to the operators of the wastewater treatment plant because they roughly approximate the amount of organic matter existing in the total solids of wastewater, activated sludge, and industrial wastes [1, 22]. **Figure 1** describes the interrelationship of solids found in water [22]. They are calculated as follows [10]:

Total solids (mg/L) = [(TSA–TSB)] × 1000/sample (mL) (3)

where TSA = weight of dried residue + dish in milligrams and TSB = weight of

and the dissolved solids pass through the filter with the water [10].

Water can be classified by the amount of TDS per liter as follows:

TON or TTN = (A + B)/A (1)

**6**

**Figure 1.** *Interrelationship of solids found in water [22].*

• Total dissolved solids:

Total dissolved solids (mg/L) = [(TDSA – TDSB)] × 1000/sample (mL) (4)

where TDSA = weight of dried residue + dish in milligrams and TDSB = weight of dish in milligrams.

• Total suspended solids:

Total suspended solids (mg/L) = [(TSSA – TSSB)] × 1000/sample (mL) (5)

where TSSA = weight of dish and filter paper + dried residue and TSSB = weight of dish and filter paper in milligram.

• Fixed and volatile suspended solids:

Volatile suspended solids (mg/L) = [(VSSA – VSSB)] × 1000/sample (mL) (6)

where VSSA = weight of residue + dish and filter before ignition, mg and VSSB = weight of residue + dish and filter after ignition, mg.

*3.1.6 Electrical conductivity (EC)*

The electrical conductivity (EC) of water is a measure of the ability of a solution to carry or conduct an electrical current [22]. Since the electrical current is carried by ions in solution, the conductivity increases as the concentration [10] of ions increases. Therefore, it is one of the main parameters used to determine the suitability of water for irrigation and firefighting.

Units of its measurement are as follows:


where (mS/m) = 10 umho/cm (1000 μS/cm = 1 dS/m).

Pure water is not a good conductor of electricity [2, 10]. Typical conductivity of water is as follows:


The electrical conductivity can be used to estimate the TDS value of water as follows [10, 22]:

$$\text{TDS (mg/L)} \cong \text{EC (dS/m or umaho/cm)} \times \text{(0.55-0.7)}\tag{7}$$

TDS can be used to estimate the ionic strength of water in the applications of groundwater recharging by treated wastewater [22]. The normal method of measurement is electrometric method [10].

#### **3.2 Chemical parameters of water quality**

#### *3.2.1 pH*

pH is one of the most important parameters of water quality. It is defined as the negative logarithm of the hydrogen ion concentration [9, 12]. It is a dimensionless number indicating the strength of an acidic or a basic solution [23]. Actually, pH of water is a measure of how acidic/basic water is [19, 20]. Acidic water contains extra hydrogen ions (H<sup>+</sup> ) and basic water contains extra hydroxyl (OH<sup>−</sup>) ions [2].

As shown in **Figure 2**, pH ranges from 0 to 14, with 7 being neutral. pH of less than 7 indicates acidity, whereas a pH of greater than 7 indicates a base solution [2, 24]. Pure water is neutral, with a pH close to 7.0 at 25°C. Normal rainfall has a pH of approximately 5.6 (slightly acidic) owing to atmospheric carbon dioxide gas [10]. Safe ranges of pH for drinking water are from 6.5 to 8.5 for domestic use and living organisms need [24].

A change of 1 unit on a pH scale represents a 10-fold change in the pH [10], so that water with pH of 7 is 10 times more acidic than water with a pH of 8, and water with a pH of 5 is 100 times more acidic than water with a pH of 7. There are two methods available for the determination of pH: electrometric and colorimetric methods [10].

**9**

*Water Quality Parameters*

substances [10].

**Figure 2.** *pH of water.*

live in the water [10].

*DOI: http://dx.doi.org/10.5772/intechopen.89657*

Excessively high and low pHs can be detrimental for the use of water. A high pH makes the taste bitter and decreases the effectiveness of the chlorine disinfection, thereby causing the need for additional chlorine [21]. The amount of oxygen in water increases as pH rises. Low-pH water will corrode or dissolve metals and other

Pollution can modify the pH of water, which can damage animals and plants that

• Most aquatic animals and plants have adapted to life in water with a specific pH

• Even moderately acidic water (low pH) can decrease the number of hatched fish eggs, irritate fish and aquatic insect gills, and damage membranes [14].

• Water with very low or high pH is fatal. A pH below 4 or above 10 will kill most fish, and very few animals can endure water with a pH below 3 or above 11 [15].

• Amphibians are extremely endangered by low pH because their skin is very sensitive to contaminants [15]. Some scientists believe that the current decrease in amphibian population throughout the globe may be due to low pH

The effects of pH on other chemicals in water can be summarized as follows:

• Heavy metals such as cadmium, lead, and chromium dissolve more easily in highly acidic water (lower pH). This is important because many heavy metals

• A change in the pH can change the forms of some chemicals in the water. Therefore, it may affect aquatic plants and animals [21]. For instance, ammonia is relatively harmless to fish in neutral or acidic water. However, as the water becomes more alkaline (the pH increases), ammonia becomes progres-

become much more toxic when dissolved in water [21].

sively more poisonous to these same organisms.

The effects of pH on animals and plants can be summarized as follows:

and may suffer from even a slight change [15].

levels induced by acid rain.

#### **Figure 2.** *pH of water.*

*Water Quality - Science, Assessments and Policy*

ity of water for irrigation and firefighting. Units of its measurement are as follows:

• U.S. units = micromhos/cm

• Ultra-pure water: 5.5 × 10<sup>−</sup><sup>6</sup>

• Drinking water: 0.005–0.05 S/m;

surement is electrometric method [10].

**3.2 Chemical parameters of water quality**

water contains extra hydrogen ions (H<sup>+</sup>

water is as follows:

• Seawater: 5 S/m.

follows [10, 22]:

*3.2.1 pH*

(OH<sup>−</sup>) ions [2].

methods [10].

living organisms need [24].

The electrical conductivity (EC) of water is a measure of the ability of a solution to carry or conduct an electrical current [22]. Since the electrical current is carried by ions in solution, the conductivity increases as the concentration [10] of ions increases. Therefore, it is one of the main parameters used to determine the suitabil-

Pure water is not a good conductor of electricity [2, 10]. Typical conductivity of

The electrical conductivity can be used to estimate the TDS value of water as

TDS can be used to estimate the ionic strength of water in the applications of groundwater recharging by treated wastewater [22]. The normal method of mea-

pH is one of the most important parameters of water quality. It is defined as the negative logarithm of the hydrogen ion concentration [9, 12]. It is a dimensionless number indicating the strength of an acidic or a basic solution [23]. Actually, pH of water is a measure of how acidic/basic water is [19, 20]. Acidic

As shown in **Figure 2**, pH ranges from 0 to 14, with 7 being neutral. pH of less than 7 indicates acidity, whereas a pH of greater than 7 indicates a base solution [2, 24]. Pure water is neutral, with a pH close to 7.0 at 25°C. Normal rainfall has a pH of approximately 5.6 (slightly acidic) owing to atmospheric carbon dioxide gas [10]. Safe ranges of pH for drinking water are from 6.5 to 8.5 for domestic use and

A change of 1 unit on a pH scale represents a 10-fold change in the pH [10], so that water with pH of 7 is 10 times more acidic than water with a pH of 8, and water with a pH of 5 is 100 times more acidic than water with a pH of 7. There are two methods available for the determination of pH: electrometric and colorimetric

TDS (mg/L) ≅ EC (dS/m or umho/cm) × (0.55–0.7) (7)

) and basic water contains extra hydroxyl

• S.I. units = milliSiemens/m (mS/m) or dS/m (deciSiemens/m)

S/m;

where (mS/m) = 10 umho/cm (1000 μS/cm = 1 dS/m).

*3.1.6 Electrical conductivity (EC)*

**8**

Excessively high and low pHs can be detrimental for the use of water. A high pH makes the taste bitter and decreases the effectiveness of the chlorine disinfection, thereby causing the need for additional chlorine [21]. The amount of oxygen in water increases as pH rises. Low-pH water will corrode or dissolve metals and other substances [10].

Pollution can modify the pH of water, which can damage animals and plants that live in the water [10].

The effects of pH on animals and plants can be summarized as follows:


The effects of pH on other chemicals in water can be summarized as follows:


#### *3.2.2 Acidity*

Acidity is the measure of acids in a solution. The acidity of water is its quantitative capacity to neutralize a strong base to a selected pH level [10]. Acidity in water is usually due to carbon dioxide, mineral acids, and hydrolyzed salts such as ferric and aluminum sulfates [10]. Acids can influence many processes such as corrosion, chemical reactions and biological activities [10].

Carbon dioxide from the atmosphere or from the respiration of aquatic organisms causes acidity when dissolved in water by forming carbonic acid (H2CO3). The level of acidity is determined by titration with standard sodium hydroxide (0.02 N) using phenolphthalein as an indicator [10, 20].

#### *3.2.3 Alkalinity*

The alkalinity of water is its acid-neutralizing capacity comprised of the total of all titratable bases [10]. The measurement of alkalinity of water is necessary to determine the amount of lime and soda needed for water softening (e.g., for corrosion control in conditioning the boiler feed water) [22]. Alkalinity of water is mainly caused by the presence of hydroxide ions (OH<sup>−</sup>), bicarbonate ions (HCO3<sup>−</sup>), and carbonate ions (CO3 <sup>2</sup><sup>−</sup>), or a mixture of two of these ions in water. As stated in the following equation, the possibility of OH<sup>−</sup> and HCO3 <sup>−</sup> ions together are not possible because they react together to produce CO3 <sup>2</sup><sup>−</sup> ions:

$$\text{CH}^+ \text{ + HCO}\_3^- \rightarrow \text{CO}\_3^{2-} \text{ + H}\_2\text{O} \tag{8}$$

Alkalinity is determined by titration with a standard acid solution (H2SO4 of 0.02 N) using selective indicators (methyl orange or phenolphthalein).

The high levels of either acidity or alkalinity in water may be an indication of industrial or chemical pollution. Alkalinity or acidity can also occur from natural sources such as volcanoes. The acidity and alkalinity in natural waters provide a buffering action that protects fish and other aquatic organisms from sudden changes in pH. For instance, if an acidic chemical has somehow contaminated a lake that had natural alkalinity, a neutralization reaction occurs between the acid and alkaline substances; the pH of the lake water remains unchanged. For the protection of aquatic life, the buffering capacity should be at least 20 mg/L as calcium carbonate.

#### *3.2.4 Chloride*

Chloride occurs naturally in groundwater, streams, and lakes, but the presence of relatively high chloride concentration in freshwater (about 250 mg/L or more) may indicate wastewater pollution [7]. Chlorides may enter surface water from several sources including chloride-containing rock, agricultural runoff, and wastewater.

Chloride ions Cl<sup>−</sup> in drinking water do not cause any harmful effects on public health, but high concentrations can cause an unpleasant salty taste for most people. Chlorides are not usually harmful to people; however, the sodium part of table salt has been connected to kidney and heart diseases [25]. Small amounts of chlorides are essential for ordinary cell functions in animal and plant life.

Sodium chloride may impart a salty taste at 250 mg/L; however, magnesium or calcium chloride are generally not detected by taste until reaching levels of

**11**

*Water Quality Parameters*

*3.2.5 Chlorine residual*

tometer [10].

*3.2.6 Sulfate*

health.

*3.2.7 Nitrogen*

*3.2.8 Fluoride*

Sulfate ions (SO4

limiting nutrient factor [10].

particularly in children [10].

blue baby or methemoglobinemia [10, 19].

colder climates, up to 2.4 mg/L is allowed.

*DOI: http://dx.doi.org/10.5772/intechopen.89657*

1000 mg/L [10]. Standards for public drinking water require chloride levels that do not exceed 250 mg/L. There are many methods to measure the chloride concentration in water, but the normal one is the titration method by silver nitrate [10].

Chlorine (Cl2) does not occur naturally in water but is added to water and wastewater for disinfection [10]. While chlorine itself is a toxic gas, in dilute aqueous solution, it is not harmful to human health. In drinking water, a residual of about 0.2 mg/L is optimal. The residual concentration which is maintained in the water

<sup>2</sup><sup>−</sup>) occur in natural water and in wastewater. The high concen-

Chlorine can react with organics in water forming toxic compounds called trihalomethanes or THMs, which are carcinogens such as chloroform CHCl3 [11, 22]. Chlorine residual is normally measured by a color comparator test kit or spectropho-

tration of sulfate in natural water is usually caused by leaching of natural deposits of sodium sulfate (Glauber's salt) or magnesium sulfate (Epson salt) [11, 26]. If high concentrations are consumed in drinking water, there may be objectionable tastes or unwanted laxative effects [26], but there is no significant danger to public

There are four forms of nitrogen in water and wastewater: organic nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen [10]. If water is contaminated with sewage, most of the nitrogen is in the forms of organic and ammonia, which are transformed by microbes to form nitrites and nitrates [22]. Nitrogen in the nitrate form is a basic nutrient to the growth of plants and can be a growth-

A high concentration of nitrate in surface water can stimulate the rapid growth of the algae which degrades the water quality [22]. Nitrates can enter the groundwater from chemical fertilizers used in the agricultural areas [22]. Excessive nitrate concentration (more than 10 mg/L) in drinking water causes an immediate and severe health threat to infants [19]. The nitrate ions react with blood hemoglobin, thereby reducing the blood's ability to hold oxygen which leads to a disease called

A moderate amount of fluoride ions (F<sup>−</sup>) in drinking water contributes to good dental health [10, 19]. About 1.0 mg/L is effective in preventing tooth decay,

Excessive amounts of fluoride cause discolored teeth, a condition known as dental fluorosis [11, 19, 26]. The maximum allowable levels of fluoride in public water supplies depend on local climate [26]. In the warmer regions of the country, the maximum allowable concentration of fluoride for potable water is 1.4 mg/L; in

distribution system ensures good sanitary quality of water [11].

1000 mg/L [10]. Standards for public drinking water require chloride levels that do not exceed 250 mg/L. There are many methods to measure the chloride concentration in water, but the normal one is the titration method by silver nitrate [10].
