Welcome to all to this lecture.
Today we will talk about drinking water supply, its needs and challenges.
When we talk about water everybody is very familiar with water and as we all know it
is an essential commodity for human well-being.
And health of human beings is directly related to the quality of water consumed.
Most of you must have experienced when you drink some water which is contaminated instantaneously
or within few hours you will be getting stomach upset and all the things.
So many times it is very clearly shown that health of human beings is directly related
to the quality of water.
So by providing sufficient quantity of safe water one can significantly reduce the expenditure
in health sector.
And people have shown that if you put around $10 or 10 rupees in providing a good quality
water and good hygienic conditions your expenditure in health sector can be reduced around 80
rupees can be reduced in the health sector.
So that is the relationship between good quality of water and health.
An integrated approach of water quality, hygiene and sanitation is essential to have a sustainable
solution for providing safe drinking water for all.
If you provide only good water supply system and we are not bothered about waste water
or solid waste or you are at the sanitation conditions then you will not be able to provide
good quality of water to all.
This show us the relationship between water quality, hygiene and sanitation.
So now when we talk about water quality, or water requirement we should know what is the
water available to us.
This shows us very clearly the fresh water availability.
You can all see that the fresh water availability is very limited.
See around 77.8% of the total water available on earth is in the form of snow and ice and
around 21.6% is existing as ground water an surface water, atmospheric water and soil
water constitute around 0.6%.
So when we talk about fresh water only availability is 2.5% of the total water in our earth and
in that one around 97.5% is salt water.
Total available water around 97.5% is salt water.
So fresh water is less than 2.5%.
So we cannot assume that water is an endless resource.
It is - its availability is very very restricted and we are seeing that the reports that many
of the countries will be sooner becoming stressed countries and recently there was some paper
articles telling that in India by 2020 more than 20 cities will become dry.
Okay because of our exploitation of water resources.
So it is very essential to conserve or augment the available water.
So how can we do the conservation of water?
There are various methods.
Rain water harvesting is one of the very proven methods of augmenting the available water
resources.
And enhancing ground water recharge.
Instead of allowing our rain water to flow to the sea if we can enhance the ground water
reach out this one will be okay enhancing our available water sources and it will be
very helpful for us in the future.
Then another one is preventing leakages.
This one I will discuss in detail little later.
If we are not maintaining our water distribution system properly around 50% of the water will
be getting lost in the water supply system because of the leakages and other means.
And when we are doing water supply system the leakage loss will be around 15% to 20%.
and another way of conserving water or augmenting water is water recycling and reuse.
Many of the industries are practicing this.
We call them Zero Liquid Discharge industries what they are doing is what are the waste
water, they are generating they are treating it into a very good quality and reusing it
in the industry itself.
So that their water consumption is almost negligible or the fresh water consumption
is almost negligible.
So nowadays industry waste water also many cities are reusing for augmenting their water
supply.
For example, [Indiscernible] [00:04:59] using around 80% of its waste water for domestic
purposes after properly treating it.
And many other countries like Singapore and even in India Chennai we are using some extend
of the treated waste water for augmenting the water supply.
So waste water recycling and reuse is also a method of conservation of water.
Another thing is we can use water conservation appurtenances for example you think about
toilet flushing.
Each time when you go to a toilet you will be using around 10 liters of water to flush
the toilet but if you can reduce that one to 5 liters or two liters as per the requirement
then you will be able to change the - you will be able to reduce the water consumption.
So that's why use water conservation appurtenances.
Another example is using sensors in taps.
Because many people have the tendency to keep the tap open when you do the hand washing
or brushing the teeth etc.
So lot of water will be wasted during those processes but if you put a sensor whenever
we need the water then only the water will be coming.
So there are many many examples so one have to think about this conservation of water.
Then another one is change in habits.
By changing the habit we will be able to save lot of water or conserve lot of water.
So now so we have talked about what is water availability etc.
When it comes to drinking water in developing countries many of us are having problem taking
the water from the tap.
We all are bothered about the quality of water.
So what are the attributes of drinking water?
When we talk about drinking water the most important things are one is aesthetic.
Another one is safety.
The water whatever we are suppose to drink should be meeting or having both these attributes.
For example, aesthetic means it should be free from color, odor, taste and it should
be pleasing that means physical perception.
And we know that any physical perception is subjective but the water should be pleasing
to the people who is going to use it.
That is one thing.
And another one is safety.
Even if the water looks very clean if it is not safe that is not good because it will
be leading to many other problems.
So when we talk about drinking water the most important water quality parameter or most
important parameter is the water should be free from bacteriological contamination or
free from pathogens because the pathogens can cause diseases immediately.
So the water should be always free from pathogens and next one is it should be free from all
intoxicants or all toxic chemicals.
This can be either Anthropogenic or natural origin because sometimes you can see that
the ground water will be having lot of fluoride, arsenic etc.
So many times these are coming from the natural minerals present in that area.
And many water sources are contaminated with heavy metals and many of these heavy metals
are coming due to Anthropogenic activities or due to industrial activities and when these
industries discharge their waste water without any treatment this waste water will find its
way to the existing water bodies either surface water or ground water.
So whenever we talk about drinking water the water should be portable, and palatable.
That means it should be pleasing and it should be safe for the people whoever is consuming
the water.
Now when we have to supply the water we have to bother about two aspects one is the quality
of the water.
Another one is the quantity of the water because we have to supply sufficient quantity of good
quality water to have healthy people.
So first we will look into water or the sources of water because we have to get enough water
from various sources and we have to give sufficient treatment to meet the requirements.
So that is what we have to do.
So when we talk about drinking water or water supply there are various sources.
For example, one source is ground water and another one is surface water.
We can see lake water.
We can see recycle-based water, etc. etc.
So when we talk about these various sources we should have some idea about the nature
of that water.
For example, ground water most of the time we think that the water is coming from deep
into the ground so the water will be clean because no waste water is there in the surface
will be reaching the ground.
But many times it may not be the right thing to think because ground water it is in contact
with the natural minerals whatever is present in that area so any time the ground water
can have various metals and non-metals like iron, magnesium, fluoride, arsenic, nitrate,
etc.
And nowadays we have seen in India many of our ground water sources are having bacteriological
contamination also.
The reason is okay whatever the waste water the domestic waste water we are discharging
without treatment it is getting pulled somewhere or it is getting into the surface water and
slowly slowly it is peculating into the ground and the ground water is getting contaminated.
So thinking that the ground water is extracted from [Indiscernible] [00:11:01] they are free
it may not be true all the time.
So we have to be careful about the quality before using it as a source.
If the quality is not meeting the required standards then we have to give sufficient
treatment to improve the quality.
So now we will see the surface water.
All of you have seen rivers, and lakes etc.
So many of the rivers are river water are contaminated with various pollutants including
pathogens, organic and inorganic pollutants and many times they will be having turbidity
etc.
So surface water also if you want to supply it as a source of drinking water okay we have
to give sufficient treatment.
Similarly when we talk about river water or lake water you will be having sometimes if
the river is stagnant and it is receiving either partially treated or untreated waste
water or the rivers will be receiving the run of from agricultural fields.
So lot of nutrients will be getting into the rivers.
So as a result they will be having algae growth.
When the algae growth is there there will be taste and odor and as we have seen earlier
pathogens maybe there and other organic and inorganic pollutants maybe there.
And you will be having turbidity etc.
So we have to look into the quality of water before we use them as drinking water.
Then another source is sea water because you know that many of the cities in the tropical
or other regions where you have water scarcity they use the sea water as a source of water
supply.
And we know that sea water is having very high concentration of salts around 35 grams
per liter.
That is too high of concentration.
If you want to use this sea water we have to give appropriate treatment like reverse
osmosis or other treatment to remove the dissolved salts before supplying to the people and as
I mentioned earlier another source is treated waste water because waste water contains around
99 more than 99% water and remaining is organic matter and some amount of microorganism.
So if you can remove the organic matter and microorganisms and other pollutants you will
be getting a good quality water.
So only thing is we have to make sure that you are giving appropriate treatment.
And this treated waste water is very reliable source of water supply because whatever the
water you are supplying about 80% will be coming as waste water.
So if you can treat and re-use it okay 80% of your water supply is met from the treated
waste water.
So this is another important source.
So now we will see in India what is the urban trends in drinking water.
And definitely the classification is based upon the wealth quantities accessibility to
all sections of the people.
So if you see the poorest people in 1995 only 8% of the people getting pipe water on premises
and by 2008 it become 17% and other improved sources that means other sources wells or
water thing which is of good quality around the total is around 80% in 1995 and it become
95% in 2008 and unimproved sources that means the quality is not assure so it was 20% and
okay by 2008 it become only 5% people are not having either pipe water supply or other
improved sources water supply who is not accessible to that water.
And next section if you take it from 20 it become 11 and 4.
You can see that as the income or as the wealth increases your accessibility to good quality
water is improving.
And when we see the middle class around 54% were having pipe water supply in 1995 and
by 2008 it was 57% significant improvement compared to the poorest.
It was 17%.
And if you see an unimproved sources it was 7% in 1995 and late 3% was lacking.
Improved or pipe water supply by 2008.
And as the wealth increases again the gap is decreasing instead of 7 it is reduce to
4 and this is remaining 3 again and the richest people richest stand next to that or upper
middle class the gap is not very significant but here you can see that pipe water supply
has increased significantly.
Now but what we are - what I am trying to tell is this is the chart prepared by the
UNICEF Statistics and Monitoring Section in 2010 what I am trying to tell is as affordability
is increasing the quality of water supplied is improving in India.
Now we will see what are the objectives of public water supply system because any city
or any town you go there is a public water supply system.
So what is the mandate of this public water supply system.
So to supply safe and good quality water in adequate quantity to population.
That is the major objective of any public water supply system.
What is this adequate quantity?
Government of India has come up with a number around 135 liters per capita per day but there
are some gradation if it is a superior urban area it can be 72 to 100 liters and all the
things but on an average one has to supply 135 liters per capita per day.
So this is the quantity one has to supply so and the public water supply system also
have to do the collection, treatment and disposal of the waste water generated in the community.
The public water supply system is not only for supplying adequate quantity of good quality
of water whatever is the water supply naturally the waste water will be generated.
So it is the duty of the public water supply engineers or public water supply firm to collect
the waste water generated and not only collect to treat and dispose the industrial waste
water.
That is also coming under their preview.
The reason why these two are integrated with the water supply system is we have seen earlier
unless you treat the waste water and provide a hygienic environment you will not be able
to provide safe and good quality water because all these untreated waste water will be spoiling
your water sources.
So that's the reason the objectives of public water supply system is not only supply water,
whatever is the waste water generated collect them properly and treat them as per the standards.
Now when we talk about this water supply system there are various components you will be having
a water source and from there you have a collection system.
You can see here very clearly so this is the water source.
It is lake, or a reservoir from that one you have the water collection system.
So water is collected from the reservoir and after that one water is getting treated in
a sunlight treatment system or [Indiscernible] [00:19:19] treatment system or sometime the
treatment can happen end of the pipe.
Then what we do the treatment is happening somewhere and the people are staying all around
the city or the town or the village so you have to have a distribution system.
The water should be sufficient quantity of water should supplied to the people.
Then you have a point of use.
So your water supply system consists of all these five components that means source, collection,
treatment, distribution, and the point of use.
Then when we talk about the water supply system what are the attributes of a good water supply
system.
There are five major attributes.
They are one is quality.
The supplied water should be of very good quality as per the standards the water should
be meeting the standards.
That is one important thing.
Another one is quantity.
The water supply system should be able to provide sufficient quantity of water because
if the system is providing very good quality but if each household is getting only 10 liters
or 20 liters of water that is not a good water supply system because each person needs around
125 liters per day of water.
So the water supply system should be able to provide enough quantity of water.
Then the next attribute is reliability.
If some system provide good quality and sufficient quantity for some days and all of a sudden
there is a breakdown or the water is not coming.
So that system is not a good system because reliability should be there.
The system should be able to provide the water.
The system should be reliable.
And fourth one is accessibility.
If you have a water supply system and the pipelines are maybe 20 meters away or 500
meters away from your household it is not a good water supply system because the people
have to walk around - people have to walk a long distance to get the water.
So that is not a good water supply system.
The water supply should be accessible to the people.
And even if all these attributes are met, like quality, quantity, reliability and accessibility.
And the price of water is very very high and many people will not be able to afford that
one.
So such a water supply system is also not good.
So the water supply system should be affordable, accessible, reliable and it should be providing
sufficient quantity of good quality of water then only we can call it as a good water supply
system.
If the water supply system is meeting all these thing people will not be having any
intimation to use the supplied water through the pipe or taps otherwise people will go
for their own treatment units or they will be going after bottled water etc.
So we have to ensure that all these attributes are met by
the water supply system.
Then we have seen water required per person is around 135 liters per day.
So when we decide the water supply system what are the other needs we have take into
account.
One is the residential or domestic water demand so that is if you know the population and
what is the water needed by a person we will be getting the water demand, domestic water
demand.
Then we have to have water for institutional purpose.
We have to have water for public or civic use that means like water in the gardens or
cleaning the roads, etc.
Then we should supply enough water for industrial use and the water supply system should be
able to take care of the system losses.
So when we calculate the water demand we have to consider all these aspects.
So here I have given the approximate division water used per person per day.
We use around 55 liters of water per day for bathing and again this will be varying from
place to place and depending upon the climatic conditions.
And washing of clothes around 20 liters.
Flushing around 30 liters.
Washing the house around 10 liters.
Washing the utensils around 10 liters.
Cooking five and drinking five.
So this is the way we are dividing the 135 liters per capita per day and I have mentioned
earlier the minimum supply should around 72 to 100 liters per capita per day in places
where they have accessibility to other water sources for some other purposes like bathing
and washing the clothes etc. then the water supply can be in the order of 70 to 100 lpcd.
So if you want to expand on the water demand when we talk about industrial use it depends
upon the type of industries.
Around 20-25% of per capita demand is used for industrial use.
This is the thumb rule for industrial use.
And water demand also should take care of the water system losses.
What are the system losses?
We can see that there can be leakage and overflow from service reservoirs many times it can
happen leakage from main and service pipelines.
Leakage and losses on consumer's premises.
And sometimes under registration of supply water because your water meters are not working
properly then again there is a loss of water from the system, then last leakage from service
taps.
So this also can happen.
So all these things will be increasing the water demand.
As I mentioned earlier in a well maintained water distribution system the losses hardly
exceeds 20%.
It is around 10 to 20% but if the system is partially metered and unmetered the losses
can go upto 50% because whatever the losses we have mentioned it can go upto 50%.
So when we design a system or something we have to look into all these aspect.
And we will look into what are the factors affecting the rate of demand.
It will be depending upon the size and type of the community, large city, less fluctuations,
and smaller habitat the fluctuations will be more.
And standard of living if higher standard of living high demand because there will be
having lot of lots and water demand for flush etc. will be very high.
Then climatic conditions.
If you are in tropical region or if it is hot area the water demand will be high but
in cold regions it will be less.
Then the quality of water, good quality more use.
Pressure of the water supply system higher pressure more use and system of supply.
If you are supplying intermittent then the demand will be reduced.
And whether you have proper sewerage system or not if you have proper sewer system the
demand will be more.
So I will stop this lecture here.
We will see the remaining part in the next lecture.
Okay. thank you very much.