water supply

1. Water Sampling
Its Purpose, Procedure, techniques &
equipments.
QUCEST,LARKANO, PAKISTAN

2. What is water Sampling?
The process of collecting a representative
portion of water, as from the natural
environment or from an industrial site, for the
purpose of analyzing it for constituents
The process of taking a portion of water for
analysis or other testing.
 e.g. drinking water to check that it complies,
or river water to check for pollutants, or
bathing water to check that it is safe.

3. Water Sampling Purpose:
The primary goal of water sampling is to observe
and measure how water quality changes over
time.
 An important premise to water sampling work is
that high acidity or high alkalinity (pH levels) in
the water might be normal for a given
environment or ecological region
water samples must be taken and analyzed
repeatedly over a period of weeks, months,
years, and decades to determine more precisely
how water conditions change.

4. Water Sampling Procedure:
1. If sampling a body of running water, point the
mouth of the bag upstream and your hands
downstream to avoid contamination.
2. If sampling from a water faucet, run the faucet
for 1 minute before obtaining a sample.
3. Rinse the bag twice with the sample water prior
to filling and closing.
4. Fill bag as full as possible. Half-filling the bottle
leaves more room for oxygen which will promote
degradation of your sample.
5. Collect data such as temperature and pH which
affect the solubility of many ions.

5. Sampling Flow Chart
Sampling
Planning
Water
Sampling
Preparation
Storage
Sampling at
the Sites
Transportation Analyses

6. Water Sampling Techniques

7. Systematic,
Random,
Judgmental (nonstatistical),
Stratified,
Haphazard
Sampling Methods

8. Systematic Sampling
For example,
The area to be analyzed may divided by a grid, and a
sample taken at each point of the grid.
For air pollution studies, an air sample might be taken at
fixed intervals of time, say every three hours.

9. Random Sampling

10. Judgmental Sampling

11. Stratified Sampling

12. Haphazard Sampling
A sampling location or sampling time is chosen arbitrarily.
This type of sampling is reasonable for a homogeneous
system.
Since most environmental systems have significant
spatial or temporal variability, haphazard sampling often
leads to biased results.
 However, this approach may be used as a preliminary
screening technique to identify a possible problem before a
full scale sampling is done.

13. Types Of Samples
Grab sample: A grab sample is a discrete sample which is
collected at a specific location at a certain point in time. If the
environmental medium varies spatially or temporally, then a
single grab sample is not representative and more samples
need to be collected.
Composite sample: A composite sample is made by
thoroughly mixing several grab samples. The whole composite
may be measured or random samples from the composites
may be withdrawn and measured.

14. Surface water Equipments

15. Rinse the sampling vessel with water on site 3~4 times. Care
must be taken to avoid contaminating water to be sampled
during rinsing.
Submerge the sampling vessel gently, fill it with the water
sample and close it tightly. If the collected water sample may
be frozen, leave some space for expansion equivalent to about
10% of the sampling vessel.
Water Sampling using Sampling Vessels

16. Simple Water Sampler

17. Buckets or Samplers with Shafts (Scoops)
Such instruments made of polyethylene are often used. A rope
can be attached to the bucket if required. Scoops with
adjustable shafts are convenient. Items made of synthetic
resins such as polypropylene can also be used. Samplers made
of stainless steel can be used provided they are not to be used
for tests on trace amounts of heavy metals.

18. Water Collection using Heyroth Water Sampler

19. Vandorn Water Sampler

20. Insulated Water Sampler

21. Ground Water Equipments

22. Bailer
A bailer in is a hollow tube used to retrieve groundwater
samples from monitoring wells. Bailers are tied to a piece of
rope or a piece of wire and lowered into the water column.
Once lowered, the bailer uses a simple ball check valve to seal
at the bottom in order to pull up a sample of the groundwater
table. Bailers can be disposable or reusable, and they are
made out of polyethylene, PVC, FEP or stainless steel.

23. Suction lift Pump
Suction-lift pumps create a vacuum
in the intake line that draws the
sample up to land surface.
Sampling is limited to situations
where water levels are within about
20 ft of the ground surface.
Vacuum effect can cause the water
to lose some dissolved gas.

24. Air-lift Samplers
The pump injects compressed air at the bottom
of the discharge pipe which is immersed in the
liquid. The compressed air mixes with the liquid
causing the air-water mixture to be less dense
than the rest of the liquid around it and
therefore is displaced upwards through the
discharge pipe by the surrounding liquid of
higher density. In general, this method is not an
appropriate method for acquisition of water
samples for detailed chemical analyses
because of degassing effect on the sample.
Oxygenation is impossible to avoid unless
elaborate precautions are taken.

25. Submersible Pump
The submersible pumps are multistage
centrifugal pumps operating in a vertical
position. Produced liquids, after being
subjected to great centrifugal forces caused
by the high rotational speed of the impeller,
lose their kinetic energy in the diffuser where a
conversion of kinetic to pressure energy takes
place. This is the main operational mechanism
of radial and mixed flow pumps.
The pump shaft is connected to the gas
separator or the protector by a mechanical
coupling at the bottom of the pump. When
fluids enter the pump through an intake screen
and are lifted by the pump stages..

26. Thank
you 