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Population Projections

Design of water supply and sanitation scheme is based on the projected population of a particular city, estimated for the design period. Any underestimated value will make system inadequate for the purpose intended; similarly overestimated value will make it costly.
Change in the population of the city over the years occurs, and the system should be designed taking into account of the population at the end of the design period.

The present and past population record for the city can be obtained from the census population records. After collecting these population figures, the population at the end of design period is predicted using various methods as suitable for that city considering the growth pattern followed by the city.

The design population will have to be estimated with due regard to all the factors governing the future growth and development of the project area in the industrial, commercial, educational, social and administration spheres. Special factors causing sudden immigration or influx of  population should also be foreseen to the extent possible.

Arithmetic Increase Method

This method is suitable for large and old city with considerable development. If it is used for small, average or comparatively new cities, it will give low result than actual value. In this method the average increase in population per decade is calculated from the past census reports. This increase is added to the present population to find out the population of the next decade. Thus, it is assumed that the population is increasing at constant rate.

Geometric Increase Method

In this method the percentage increase in population from decade to decade is assumed to remain constant. Geometric mean increase is used to find out the future increment in population. Since this method gives higher values and hence should be applied for a new
industrial town at the beginning of development for only few decades.

Incremental Increase Method

This method is modification of arithmetical increase method and it is suitable for an average size town under normal condition where the growth rate is found to be in increasing order. While adopting this method the increase in increment is considered for calculating future population. The incremental increase is determined for each decade from the past population and the average value is added to the present population along with the average rate of increase.

Decreasing rate of Growth

In this method it is assumed that rate of percentage increase decreases and the average decrease in the rate of growth is calculated. Then the percentage increase is modified by deducting the decrease in rate of growth. This method is applicable only in such cases
where the rate of growth of population shows a downward trend.

Graphical Method

In this method, the populations of last few decades are correctly plotted to a suitable scale on graph. The population curve is smoothly extended for getting future population. This extension should be done carefully and it requires proper experience and judgment. The best way of applying this method is to extend the curve by comparing with population curve of some other similar cities having the similar growth condition.

Comparative Graphical Method

In this method the census populations of cities already developed under similar conditions are plotted. The curve of past population of the city under consideration is plotted on the same graph. The curve is extended carefully by comparing with the population curve of some similar cities having the similar condition of growth. The advantage of this method is that the future population can be predicted from the present population even in the absent of some of the past census report.

Master Plan (Density)Method

The big and metropolitan cities are generally not developed in haphazard manner, but are planned and regulated by local bodies according to master plan. The master plan is prepared for next 25 to 30 years for the city. According to the master plan the city is divided into various zones such as residence, commerce and industry. The population densities are fixed for various zones in the master plan. From this population density total water demand and wastewater generation for that zone can be worked out. So by this method it is very easy to access precisely the design population.

Logistic Curve Method

This method is used when the growth rate of population due to births, deaths and migrations takes place under normal situation and it is not subjected to any extraordinary changes like epidemic, war, earth quake or any natural disaster etc. the population follow the growth curve characteristics of living things within limited space and economic opportunity. If the population of a city is plotted with respect to time, the curve so obtained under normal condition is look like S-shaped curve and is known as logistic curve.

Projected population is calculated by;



P = Population at any time t

Ps = Saturation Population

t = time in years

For only three pairs of characteristic values P0, P1, P2 at times t = t0 = 0, t1and t2 = 2t1 extending over the past record




Component Method

Main reasons of the population change are birth, death and migration. Where information regarding births and deaths is available, the natural increase can be easily estimated. When calculating, net migration should be calculated first, otherwise it will not affect the number of births and deaths recorded.
It is a useful method when migration is not the main factor in population change.

Design Period

The design period is not the same as the life expectancy. The design period is the length of time it is estimated that the facility will be able to meet the demand, that is, the design capacity. The life expectancy of a facility or piece of equipment is determined by wear and tear.

The complete water supply project includes huge and costly constructions such as dams, reservoirs, treatment works and network of distribution pipelines. These all works cannot be replaced easily or capacities increased conveniently for future expansions.
While designing and constructing these works, they should have sufficient capacity to meet future demand of the town for number of years. The number of years for which the designs of the water works have been done is known as design period. Mostly water works are designed for design period of 20-30 years, which is fairly good period.

New water supply projects are generally made large enough to meet the demand for the future. The number of years selected for the design period is based on the following:

  • Regulatory constraints.
  • Population growth rate
  • Interest rate on Capital.
  • The useful life of the structures and equipment.
  • The ease or difficulty of expansion.
  • Performance in early years of life under minimum hydraulic load.

Although other indicators may lead to the conclusion that a long design period is favored, serious consideration must be given to the impact of low flow rates in the early years of the project. In addition to the behavior and efficiency of the unit operations, the impact
on the energy efficiency of the equipment should be evaluated. A successful alternative is the use of modular units and construction of hardened facilities without installation of mechanical equipment until the units are needed.

Design periods that are commonly employed in practice and commonly experienced life expectancies are shown in Table below;

Type of facility Characteristics Design period Life expectancy
Large dams and pipelines Difficult and expensive to enlarge 40–60 100
Wells Easy to refurbish & replace 15–25 25
Treatment plants Fixed facilities Difficult and expensive to enlarge or replace 20–25 50
Equipment Easy to refurbish or replace 10–15 10–20
Distribution systems Mains  60 cm Replacement is expensive and difficult 20–25 60
Distribution systems Laterals and mains  30 cm Easy to refurbish or replace To full development 40–50



As per CPHEEO Manual, the recommendations for design period of various facilities is as below;

The water supply infrastructural is normally designed for a period of thirty years after their completion. The time lag between design & completion of a project should also be taken into account. Necessary land for future expansion of facilities should be acquired in the beginning itself. Expensive tunnels and large aqueducts should be designed for ultimate project demand. Where failure of components is forseeable, such components shall be provided in duplicate.

Some major components of Water Supply Project may be designed for a design period as below;

S.No. Items Design Period in Years
1 Storage by Dams 50
2 Infiltration Works 30
3 i Pumping – Pump House Civil Works 30
3 ii Electric Motors and pumps 15
4 Water Treatment Units 15
5 Pipe Connections to several treatment units and other small appurtenances 30
6 Raw Water and Clear Water Conveying Mains 30
7 Clear Water Reservoir at the head works & balancing tank and service reservoirs (overhead or ground level) 15
8 Distribution System 30




Disinfection is an important step in ensuring that water is safe to drink. Water systems add disinfectants to destroy microorganisms that can cause disease in humans. Disinfection kills or inactivates disease-causing organisms in a water supply and must provide a 99.9 percent inactivation of Giardia lamblia cysts and enteric viruses to protect health.

There are two kinds of disinfection: primary disinfection achieves the desired level of microorganism kill or inactivation, while secondary disinfection maintains a disinfectant residual in the finished water that prevents the regrowth of microorganisms.

Our natural environment contains numerous microorganisms. Most of these present no concerns. However, some—such as Giardia lamblia and various viruses, which can be present in water supplies—are extremely harmful and can cause disease in humans. These disease-causing organisms are known as pathogens.

Because pathogens can be present in drinking water supplies, disinfection is very important for surface water and groundwater under the influence of surface water. Disinfection treatment methods include chlorination, chlorine dioxide, chloramines, ozone, and ultraviolet light. When combined with conventional treatment, such as coagulation, flocculation, sedimentation, and filtration, good results have been obtained. Direct filtration, slow sand filtration, and diatomaceous earth filtration, along with disinfection, have been just as successful.

Groundwater systems that disinfect may have to add filtration if the water contains iron and manganese. In fact, insoluble oxides form when chlorine, chlorine dioxide, or ozone are added to these systems. Both ozonation and chlorination may cause flocculation of dissolved organics, thus increasing turbidity and necessitating filtration.

The effectiveness of disinfection is judged by analyzing for an indicator organism (total coliform bacteria). This organism is considered harmless, but its presence indicates that pathogens may also have survived.

Historically, boiling of water or use of copper and silver vessels for storing water which effect some measure of disinfection have been employed. Modern disinfection processses include use of

  • Physical methods such as thermal treatment and ultrasonic waves
  • Chemicals including oxidizing agents such as chlorine & its compounds, Bromine, Iodine, Potassium Permagnate, Ozone and metals like silver
  • Radiation

Criteria for good disinfectant

To be a good disinfection agent, it should satisfy following criteria;

  • It shall be capable of destroying the pathogenic organism present within the contact period available and not unduly influenced by the range of chemical & physical properties of water
  • Should not leave products of reaction which render he water toxic or impart colour or otherwise make it unpotable.
  • Possess the property of leaving residual concentration to deal with possible recontamination
  • Be amenable to detection by practical, rapid and simple analytical techniques in the small concentration ranges to permit control of disinfection processes.

 Factors affecting efficiency of disinfection

The efficiency of chemical disinfection is influenced by following factors;

  • Type, condition concentration and distribution of organisms to be destroyed
  • Type & concentration of disinfectant
  • Chemical & Physical properites of water to be treated
  • Contact Time available for disinfection
  • Temperature of water

Contact Time

Under ideal conditions and at constant temperature, the number of organism (Nt) surviving after a period of time t is related to the initial number (No) by Chicks Law

log(No/Nt) = k.t

Where k is a constant with dimension 1/T
Departures from Chicks law are not uncommon. Rates of kill have been experimentally observed to increase with time in some cases and decrease with time in other cases. To account for these departures from Chicks law, the following modified equation has been suggested

log(No/Nt) = k.t^m

Where m is a constant. If m is greater than 1 then the rate of kill increases with time and if m is less than 1, the rate of kill decreases with time.

Concentration of disinfectant

Rate of disinfection is affected, within limits, by changes in concentration of disinfectant. The relation between disinfectant concentration and time required for killing a desired percentage of organism is generally expressed by following equation;

C^n . tp = Constant

Where C is the concentration of disinfectant, n is a coefficient of dilution and t is the time required for a constant percentage kill of the organisms. Value of n greater than 1 indicates rapid decrease in efficiency of disinfectant as its concentration is reduced, if n is less than 1, contact time is more important than concentration and if n is equal to 1, both affect the efficiency of disinfection to some extent.

Temperature of Water

The effect of temperature on rate of kill is usually expressed by the Vant Hoff-Arrhenius relationship assuming that the rate of disinfection is controlled by either rate of diffusion of disinfectant through the cell wall or by rate of chemical reaction with cellular enzymes.

Log t1/t2 = E(T2-T1)/(2.303R.T1.T2)

where t1, t2 are time given for given percentage of kill at Temperature T1 and T2 in Degree Kelvin, E is the activation energy in J/mol or cals/mol and R is gas constant equal to 8.314 J/molDegree Kelvin or 1.99 cals/mol.Degree Kelvin. Typical values of E at pH 7.0 for aqueous chlorine and chloramines are 34332 and 50242 J/mol respectively. This type of relationship indicates that at lower temperature of water i.e. in winter season, the time required for achieving the same percentage of kill for the same concentration of disinfectant would be higher than those for higher temperature i.e. in summer season.

Drinking Water Contaminants

Drinking water is derived from two basic sources: surface waters, such as rivers and reservoirs, and groundwater. All water contains natural contaminants, particularly inorganic contaminants that arise from the geological strata through which the water flows and, to a varying extent, anthropogenic pollution by both microorganisms and chemicals. In general, groundwater is less vulnerable to pollution than surface waters. There are a number of possible sources of man-made contaminants, some of which are more important than others. These fall into the categories of point and diffuse sources. Discharges from industrial premises and sewage treatment works are point sources and as such are more readily identifiable and controlled; run off from agricultural land and from hard surfaces, such as roads, are not so obvious, or easily controlled. Such sources can give rise to a significant variation in the contaminant load over time. There is also the possibility of spills of chemicals from industry and agriculture and slurries from intensive farm units that can contain pathogens. In some countries, badly sited latrines and septic tanks are a significant source of contamination, especially of wells. Local industries can also give rise to contamination of water sources, particularly when chemicals are handled and disposed of without proper care. The run-off or leaching of nutrients into slow flowing or still surface waters can result in excessive growth of cyanobacteria or blue-green algae. Many species give rise to nuisance chemicals that can cause taste and odour and interfere with drinking water treatment. However, they frequently produce toxins, which are of concern for health, particularly if there is only limited treatment.

If treatment is not optimized, unwanted residues of chemicals used in water treatment can also cause contamination, and give rise to sediments in water pipes. Contamination during water distribution may arise from materials such as iron, which can corrode to release iron oxides, or from ingress of pollutants into the distribution system. Diffusion through plastic pipes can occur, for example when oil is spilt on the surrounding soil, giving rise to taste and odour problems. Contamination can also take place in consumers’ premises from materials used in plumbing, such as lead or copper, or from the back-flow of liquids into the distribution system as a consequence of improper connections. Such contaminants can be either chemical or microbiological.

A list of drinking water contaminants is provided below (Source:EPA);


Contaminant Potential Health Effects from Long-Term Exposure Sources of Contaminant in Drinking Water
Cryptosporidium Gastrointestinal illness (such as diarrhea, vomiting, and cramps) Human and animal fecal waste
Giardia lamblia Gastrointestinal illness (such as diarrhea, vomiting, and cramps) Human and animal fecal waste
Heterotrophic plate count (HPC) HPC has no health effects; it is an analytic method used to measure the variety of bacteria that are common in water. The lower the concentration of bacteria in drinking water, the better maintained the water system is. HPC measures a range of bacteria that are naturally present in the environment
Legionella Legionnaire’s Disease, a type of pneumonia Found naturally in water; multiplies in heating systems
Total Coliforms (including fecal coliform and E. Coli) Not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present5 Coliforms are naturally present in the environment; as well as feces; fecal coliforms andE. coli only come from human and animal fecal waste.
Turbidity Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness (such as whether disease-causing organisms are present). Higher turbidity levels are often associated with higher levels of disease-causing microorganisms such as viruses, parasites and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches. Soil runoff
Viruses (enteric) Gastrointestinal illness (such as diarrhea, vomiting, and cramps) Human and animal fecal waste


Disinfection By Products

Contaminant Potential Health Effects from Long-Term Exposure Sources of Contaminant in Drinking Water
Bromate Increased risk of cancer Byproduct of drinking water disinfection
Chlorite Anemia; infants and young children: nervous system effects Byproduct of drinking water disinfection
Haloacetic acids (HAA5) Increased risk of cancer Byproduct of drinking water disinfection
Total Trihalomethanes (TTHMs) Liver, kidney or central nervous system problems; increased risk of cancer Byproduct of drinking water disinfection



Contaminant Potential Health Effects from Long-Term Exposure Sources of Contaminant in Drinking Water
Chloramines (asCl2) Eye/nose irritation; stomach discomfort, anemia Water additive used to control microbes
Chlorine (as Cl2) Eye/nose irritation; stomach discomfort Water additive used to control microbes
Chlorine dioxide (as ClO2) Anemia; infants and young children: nervous system effects Water additive used to control microbes


Inorganic Chemicals

Contaminant Potential Health Effects from Long-Term Exposure Sources of Contaminant in Drinking Water
Antimony Increase in blood cholesterol; decrease in blood sugar Discharge from petroleum refineries; fire retardants; ceramics; electronics; solder
Arsenic Skin damage or problems with circulatory systems, and may have increased risk of getting cancer Erosion of natural deposits; runoff from orchards, runoff from glass and electronicsproduction wastes
Asbestos (fiber > 10 micrometers) Increased risk of developing benign intestinal polyps Decay of asbestos cement in water mains; erosion of natural deposits
Barium Increase in blood pressure Discharge of drilling wastes; discharge from metal refineries; erosion of natural deposits
Beryllium Intestinal lesions Discharge from metal refineries and coal-burning factories; discharge from electrical, aerospace, and defense industries
Cadmium Kidney damage Corrosion of galvanized pipes; erosion of natural deposits; discharge from metal refineries; runoff from waste batteries and paints
Chromium (total) Allergic dermatitis Discharge from steel and pulp mills; erosion of natural deposits
Copper Short term exposure: Gastrointestinal distressLong term exposure: Liver or kidney damage

People with Wilson’s Disease should consult their personal doctor if the amount of copper in their water exceeds the action level

Corrosion of household plumbing systems; erosion of natural deposits
Cyanide (as free cyanide) Nerve damage or thyroid problems Discharge from steel/metal factories; discharge from plastic and fertilizer factories
Fluoride Bone disease (pain and tenderness of the bones); Children may get mottled teeth Water additive which promotes strong teeth; erosion of natural deposits; discharge from fertilizer and aluminum factories
Lead Infants and children: Delays in physical or mental development; children could show slight deficits in attention span and learning abilitiesAdults: Kidney problems; high blood pressure Corrosion of household plumbing systems; erosion of natural deposits
Mercury (inorganic) Kidney damage Erosion of natural deposits; discharge from refineries and factories; runoff from landfills and croplands
Nitrate (measured as Nitrogen) Infants below the age of six months who drink water containing nitrate in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. Runoff from fertilizer use; leaking from septic tanks, sewage; erosion of natural deposits
Nitrite (measured as Nitrogen) Infants below the age of six months who drink water containing nitrite in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. Runoff from fertilizer use; leaking from septic tanks, sewage; erosion of natural deposits
Selenium Hair or fingernail loss; numbness in fingers or toes; circulatory problems Discharge from petroleum refineries; erosion of natural deposits; discharge from mines
Thallium Hair loss; changes in blood; kidney, intestine, or liver problems Leaching from ore-processing sites; discharge from electronics, glass, and drug factories


Organic Chemicals

Contaminant Potential Health Effects from Long-Term Exposure Sources of Contaminant in Drinking Water
Acrylamide Nervous system or blood problems; increased risk of cancer Added to water during sewage/wastewater treatment
Alachlor Eye, liver, kidney or spleen problems; anemia; increased risk of cancer Runoff from herbicide used on row crops
Atrazine Cardiovascular system or reproductive problems Runoff from herbicide used on row crops
Benzene Anemia; decrease in blood platelets; increased risk of cancer Discharge from factories; leaching from gas storage tanks and landfills
Benzo(a)pyrene (PAHs) Reproductive difficulties; increased risk of cancer Leaching from linings of water storage tanks and distribution lines
Carbofuran Problems with blood, nervous system, or reproductive system Leaching of soil fumigant used on rice and alfalfa
Carbon tetrachloride Liver problems; increased risk of cancer Discharge from chemical plants and other industrial activities
Chlordane Liver or nervous system problems; increased risk of cancer Residue of banned termiticide
Chlorobenzene Liver or kidney problems Discharge from chemical and agricultural chemical factories
2,4-D Kidney, liver, or adrenal gland problems Runoff from herbicide used on row crops
Dalapon Minor kidney changes Runoff from herbicide used on rights of way
1,2-Dibromo-3-chloropropane (DBCP) Reproductive difficulties; increased risk of cancer Runoff/leaching from soil fumigant used on soybeans, cotton, pineapples, and orchards
o-Dichlorobenzene Liver, kidney, or circulatory system problems Discharge from industrial chemical factories
p-Dichlorobenzene Anemia; liver, kidney or spleen damage; changes in blood Discharge from industrial chemical factories
1,2-Dichloroethane Increased risk of cancer Discharge from industrial chemical factories
1,1-Dichloroethylene Liver problems Discharge from industrial chemical factories
cis-1,2-Dichloroethylene Liver problems Discharge from industrial chemical factories
trans-1,2-Dichloroethylene Liver problems Discharge from industrial chemical factories
Dichloromethane Liver problems; increased risk of cancer Discharge from drug and chemical factories
1,2-Dichloropropane Increased risk of cancer Discharge from industrial chemical factories
Di(2-ethylhexyl) adipate Weight loss, liver problems, or possible reproductive difficulties. Discharge from chemical factories
Di(2-ethylhexyl) phthalate Reproductive difficulties; liver problems; increased risk of cancer Discharge from rubber and chemical factories
Dinoseb Reproductive difficulties Runoff from herbicide used on soybeans and vegetables
Dioxin (2,3,7,8-TCDD) Reproductive difficulties; increased risk of cancer Emissions from waste incineration and other combustion; discharge from chemical factories
Diquat Cataracts Runoff from herbicide use
Endothall Stomach and intestinal problems Runoff from herbicide use
Endrin Liver problems Residue of banned insecticide
Epichlorohydrin Increased cancer risk, and over a long period of time, stomach problems Discharge from industrial chemical factories; an impurity of some water treatment chemicals
Ethylbenzene Liver or kidneys problems Discharge from petroleum refineries
Ethylene dibromide Problems with liver, stomach, reproductive system, or kidneys; increased risk of cancer Discharge from petroleum refineries
Glyphosate Kidney problems; reproductive difficulties Runoff from herbicide use
Heptachlor Liver damage; increased risk of cancer Residue of banned termiticide
Heptachlor epoxide Liver damage; increased risk of cancer Breakdown of heptachlor
Hexachlorobenzene Liver or kidney problems; reproductive difficulties; increased risk of cancer Discharge from metal refineries and agricultural chemical factories
Hexachlorocyclopentadiene Kidney or stomach problems Discharge from chemical factories
Lindane Liver or kidney problems Runoff/leaching from insecticide used on cattle, lumber, gardens
Methoxychlor Reproductive difficulties Runoff/leaching from insecticide used on fruits, vegetables, alfalfa, livestock
Oxamyl (Vydate) Slight nervous system effects Runoff/leaching from insecticide used on apples, potatoes, and tomatoes
Polychlorinated biphenyls (PCBs) Skin changes; thymus gland problems; immune deficiencies; reproductive or nervous system difficulties; increased risk of cancer Runoff from landfills; discharge of waste chemicals
Pentachlorophenol Liver or kidney problems; increased cancer risk Discharge from wood preserving factories
Picloram Liver problems Herbicide runoff
Simazine Problems with blood Herbicide runoff
Styrene Liver, kidney, or circulatory system problems Discharge from rubber and plastic factories; leaching from landfills
Tetrachloroethylene Liver problems; increased risk of cancer Discharge from factories and dry cleaners
Toluene Nervous system, kidney, or liver problems Discharge from petroleum factories
Toxaphene Kidney, liver, or thyroid problems; increased risk of cancer Runoff/leaching from insecticide used on cotton and cattle
2,4,5-TP (Silvex) Liver problems Residue of banned herbicide
1,2,4-Trichlorobenzene Changes in adrenal glands Discharge from textile finishing factories
1,1,1-Trichloroethane Liver, nervous system, or circulatory problems Discharge from metal degreasing sites and other factories
1,1,2-Trichloroethane Liver, kidney, or immune system problems Discharge from industrial chemical factories
Trichloroethylene Liver problems; increased risk of cancer Discharge from metal degreasing sites and other factories
Vinyl chloride Increased risk of cancer Leaching from PVC pipes; discharge from plastic factories
Xylenes (total) Nervous system damage Discharge from petroleum factories; discharge from chemical factories



Contaminant Potential Health Effects from Long-Term Exposure Sources of Contaminant in Drinking Water
Alpha particles Increased risk of cancer Erosion of natural deposits of certain minerals that are radioactive and may emit a form of radiation known as alpha radiation
Beta particles and photon emitters
Increased risk of cancer Decay of natural and man-made deposits ofcertain minerals that are radioactive and may emit forms of radiation known as photons and beta radiation
Radium 226 and Radium 228 (combined) Increased risk of cancer Erosion of natural deposits
Uranium Increased risk of cancer, kidney toxicity Erosion of natural deposits






EPANET is software, developed by Environment Protection Agency (EPA) of USA, for hydraulic modelling of water supply networks. It is a public domain software, free to download and use. The link for the download page is

EPANET download page.

It performs steady state as well as extended-period simulation of the hydraulic and water quality behavior within pressurized pipe networks.

It  provides an integrated computer environment for editing network input data, running hydraulic and water quality simulations, and viewing the results in a variety of formats. These include color-coded network maps, data tables, time series graphs, and contour plots.


AWWA Manuals of Water Supply Practices

American Water Works Association (AWWA) publishes a number of Manuals on Water Supply Practices. A complete list is available below;
Manual No
M1principles of Water rates, fees, and Charges, fifth edition
M2instrumentation & Control, third edition
M3safety practices for Water utilities, sixth edition
M4Water fluoridation principles and practices, fifth edition
M5Water utility Management, second edition
M6Water Meters: Selection, Installation, Testing & Maintenance, fifth edition
M7problem organisms in Water: identification & treatment, third edition
M9Concrete pressure pipe, third edition
M11steel pipe: A guide for Design and installation, fourth edition
M12simplified procedures for Water examination, fifth edition
M14recommended practice for Backflow prevention and Cross-Connection Control
M17installation, field testing, & Maintenance of fire Hydrants, fourth edition
M19emergency planning for Water utilities, fourth edition
M20Water Chlorination & Chloramination practices & principles, second edition
M21groundwater, third edition
M22sizing Water service lines and Meters, second edition
M23pVC pipe Design and installation, second edition
M24planning for the Distribution of reclaimed Water, third edition
M25flexible Membrane Covers and linings for potable-Water reservoirs, third edition
M27external Corrosion: introduction to Chemistry and Control, second edition
M28rehabilitation of Water Mains, second edition
M29fundamentals of Water utility Capital financing, third edition
M30precoat filtration, second edition
M31Distribution system requirements for fire protection, fourth edition
M32Computer Modeling of Water Distribution Systems, third edition
M33flowmeters in Water supply, second edition
M36Water Audits and loss Control programs, third edition
M37Operational Control of Coagulation and Filtration Processes, third edition
M38electrodialysis and electrodialysis reversal
M41Ductile-iron pipe and fittings, third edition
M42steel Water-storage tanks
M44Distribution Valves: selection, installation, field testing & Maintenance, second
M45fiberglass pipe Design, second edition
M46reverse osmosis and Nanofiltration, second edition
M47Capital project Delivery, second edition
M48Waterborne pathogens, second edition
M49Butterfly Valves: torque, Headloss and Cavitation Analysis
M50Water resources planning, second edition
M51Air-release, Air/Vacuum & Combination Air Valves
M52Water Conservation programs: A planning Manual
M53Microfiltration and ultrafiltration Membranes for Drinking Water
M54Developing rates for small systems
M55pe pipe design and installation
M56fundamentals & Control of Nitrification in Chloraminated Drinking Distribution systems
M57Algae: source to treatment
M58internal Corrosion Control in Water Distribution systems
M60Drought Preparedness and Response
M61Desalination of Seawater

Water specific Observances

Observance denotes a period of time to observe some issue of international interest or concern. This is used to commemorate, promote and mobilize for action.
Some of the observances specific to water are as follows;
February 2World Wetlands Day
March 22World Water Day
April 22Earth Day
May 25World Meteorological Day
June 5World Environment Day
June 8World Ocean Day

LOOP program in Window 7

Network modelling program – “LOOP” is a DOS based program, which do not runs by itself in Window 7. To run DOS program in Window 7, we need a DOS Emulator. An open source DOS emulator is DOSBOX which can be downloaded free from www.dosbox.com. Step by Step procedure for running “LOOP” in window 7 is as below;

  • Download the emulator DOSBOX and install it in directory c:\dosbox.
  • We have LOOP program installed in directory C:\loop.
  • Run the DOSBOX program
  • At prompt of DOSBOX program (Z:\>), mount your loop folder as follows;
    • Z:\>MOUNT C C:\LOOP
  • Drive C mounted as local directory C:\LOOP\
  • After this done, we will be prompted with a Z:\>
  • Navigate to newly mounted drive as follows;
    • Z:\>C:
    • C:\>
  • Now we are ready to run the LOOP program
    • C:\>loop

For detailed instruction, you can refer to DOSBOX documentation. LOOP program is available on our “freebies” Page.

Anaerobic Treatment of Wastewater

A presentation on Anaerobic Treatment of Wastewater

CPHEEO Manuals on Scribd

The links for three CPHEEO manuals as available on Scribd are as follows;

Manual of Water Supply & Treatment

Manual of Sewerage & Sewage Treatment

Manual on Operation & Maintenance of Water Supply Systems

Plastic Pipe Calculator

An excellent calculator for plastic pipes covering all aspects of design. The calculator uses formula from handbook of polyethylene pipes by Plastic Pipe Institute.
The link is as below;

Plastic Pipe Calculator

Partial Flow in Circular Pipes

Partial Flow in Circular Pipes

jsWater Calculator
Hydraulic Properties Calculator for Partial Flow in Circular Pipes



The velocity of flow for gravity flow is provided by mannings equation, which is as follows;


V = Velocity of Flow in m/s,

R = Hydraulic Radius in meters,

S = Slope, unitless,

n = Manning’s Coefficient

The circular channel running part-full is very commonly met with. The flow occupies a segment of the circle of total angle 2α, related to the depth y. For partially full pipe the following relations are applied:
Depth Ratio
d/D=1/2(1-cos theta/2)
Area Ratio
a/A=(theta/360-(sin theta)/2*pi)
Hydraulic Radius Ratio
r/R=(1 - (360*sin theta )/ (2*pi*theta))
Velocity Ratio
v/V = (r/R)^(2/3)
Flow Ratio
q/Q = (a/A) * (v/V)

Here, notations d,a,r,v,q are for partial flow and D,A,R,V,Q are for full pipe flow.

Mannings Coefficients

Type of material
Salt glazed stone ware pipeGood0.012
Cement concrete pipes (with collar joints)Good0.013
Spun concrete pipes (with socket and spigot joint)0.011
Neat cement plaster0.018
Sand and cement plaster0.015
Concrete, steel trowled0.014
Concrete, wood trowled0.015
Brick in good condition0.015
Brick in rough condition0.017
Masonry in bad condition0.02
Stone work
Smooth dressed Ashlar0.015
Rubble set in cement0.017
Fine, well packed gravel0.02
Regular surface in good condition0.02
In ordinary condition0.025
With stones and weeds0.03
In poor condition0.035
Partially obstructed with debris or weeds0.05
Slightly tuberculated0.02
With spun cement mortar lining0.011
Cast iron
With spun cement mortar lining0.011
Asbestos cement0.011