- Groundwater sampling requires taking a representative sample, properly rinsing sample bottles, filtering and preserving samples in the field, taking accurate field measurements, storing samples on ice, and sending them to a certified lab within 24 hours. It also requires a quality control program. - There are several methods for collecting groundwater samples, including using in-place plumbing or pumps for wells with or without plumbing. - Basic water quality parameters that can be tested in the field include pH, conductivity, salinity, turbidity, dissolved oxygen, and temperature, while laboratories can analyze for cations, anions, trace metals, and radioactivity.

1. Groundwater Sampling
• Important Points
– Be sure to take a representative sample
– Make sure sample bottles are properly rinsed
– Filter and preserve samples in the field
– Take field measurements with proper equipment
– Store on ice
– Send to a certified water chemistry laboratory within
24 hours of sampling
– Have a quality control program with duplicates,
blanks, field blanks, or spiked samples

2. Groundwater Sampling Methods
Sampling is the process of obtaining, containerizing, and preserving (if required) a
ground water sample after the purging process is complete.
There are few technical methods, which can be adopted for collection of
representative samples are-
 Sampling Wells With In-Place Plumbing
Samples should be collected following purging from a valve or cold water tap as
near to the well as possible, preferably prior to any storage/pressure tanks or
physical/chemical treatment system that might be present.
 Sampling Wells Without Plumbing, Within the Limit of Suction
The pump of choice for sampling ground water within the limit of suction is the
variable- speed peristaltic pump. Its use is described in the following sections.
Other acceptable alternatives that may be used under these conditions are the
RediFlo2® electric submersible pump (with Teflon® tubing) and a closed-top
Teflon® bailer.
(variable speed peristaltic pump/ Peristaltic Pump/ Vacuum jug/ RediFlo2
Electric Submersible Pump/ Bailers)

3. Basic Water Quality Parameters
• pH
• Specific conductance (EC)
• Salinity
• Total dissolved solids (TDS)
• Turbidity
• Dissolved oxygen (DO)
• Biochemical oxygen demand (BOD)
• Temperature
• Total Hardness

4. ANALYSIS OF WATER SAMPLES
• Field:
– pH, specific conductance, temperature,
dissolved oxygen, and alkalinity
• Laboratory:
– Cations: sodium, calcium magnesium,
potassium, and iron
– Anions: bicarbonate, carbonate, sulfate, and
chloride
– Trace Metals, Radioactivity

5. Ground water Quality &
Associated Problems
Indian Sub- Continent is endowed with diverse geological formations from
oldest Achaeans to Recent alluviums and characterized by varying climatic
conditions in different parts of the country.
The main ground water quality problems in India are as follows-


Inland Salinity (Rajasthan, Haryana, Gujarat, Andhra Pradesh, Maharashtra,
Tamil Nadu etc.)
Coastal Salinity (The Indian subcontinent has a dynamic coastline of about
7500 km length, which stretches from Rann of Kutch in Gujarat to Konkan
and Malabar coast to Kanyakumari)
3 probable cases of coastal salinity
 Saline water overlying fresh water aquifer
 Fresh water overlying saline water
 Alternating sequence of fresh water and saline water aquifers

6. Sodium and Irrigation
•
•
•
•
•
Sodium reacts with soil to reduce permeability.
Alkali soils - High sodium with carbonate
Saline soils – High sodium with chloride or sulphate
Neither support plant growth
Sodium Adsorption Ratio (SAR) is a measure of the suitability of water
for use in agricultural irrigation, as determined by the concentrations of solids dissolved in
the water. It is also a measure of the sodicity of soil, as determined from analysis of water
extracted from the soil.

7. Sodium and Irrigation
•
•
•
•
Low-sodium water
– Used on all soils with little danger of harmful levels of
exchangeable sodium.
Medium-sodium water
– appreciable sodium hazard in certain fine-textured soils
High-sodium water
– harmful levels of exchangeable sodium in most soils
– require special soil management such as good drainage,
leaching, and additions of organic matter.
Very high sodium water
– unsatisfactory for irrigation unless special action is taken,
such as addition of gypsum to the soil

8. Salinity and irrigation
• Low salinity water
– used for most crops
• Medium salinity water
– used with moderate amount of leaching (potatoes,
corn, wheat, oats, and alfalfa)
• High salinity water
– Cannot be used on soils having restricted drainage.
• Very high salinity water
– Can be used only on certain crops and then only if
special practices are followed

9. Alkalinity
• “acid neutralizing capacity”
• Important because it buffers the water against
changes in pH
• For most waters, alkalinity includes the
bicarbonate ion (HCO3)
-
• Other ions such as orthophosphate (HPO4
-),
borates, may contribute to alkalinity but in
small amounts

10. pH
•
•
•
•
Measures hydrogen ion
concentration
Negative log of hydrogen ion
concentration
Ranges from 0 to 14 std. units
pH
– 7 neutral
– 0 - 7 acidic
– 7 - 14 alkaline
Thanks to Phil Brown

11. Conductivity
•
•
•
•
•
Measures electric
conductivity (EC) of water
Higher value means water
is a better electrical
conductor
Increases when more salt
(e.g., sodium chloride) is
dissolved in water
Indirect measure of salinity
Units are μmhos/cm at 25o
C or μsiemens/cm
Thanks to Phil Brown

12. Electrical conductivity of GW due
to presence of salts

13. Salinity
•
•
Classification of Ground Water
Composition Based on Total Dissolved
Solids Content
Salts in Sea Water
Type of Water Dissolved salt content (mg/l)
< 1,000 mg/l
1,000 - 3,000 mg/l
3,000 - 10,000 mg/l
Fresh water
Brackish water
Moderatly saline
water
Highly saline water
Sea water
10,000 - 35,000 mg/l
> 35,000 mg/l

14. Dissolved Oxygen
•
•
•
•
•
Amount of gaseous oxygen
(O2) dissolved in water
Oxygen gets into water by
diffusion from the
surrounding air, by
aeration, and through
photosynthesis
DO range from 0-18 mg/l
Need 5-6 mg/l to support a
diverse population
DO < 2 mg/l - Hypoxia
Thanks to Phil Brown

15. Turbidity• Measured in Nephelometric
•
Turbidity Units (NTU)
Estimates light scattering by
suspended particles
• Photocell
direction
estimate
set at 90oto the of
light beam to
scattered rather
than absorbed light
• Good correlation with
concentration of particles in
water
Thanks to Phil Brown
YSI 556 MPS
HF Scientific MicroTPI
– Turbidity Meter

16. Total Dissolved Solids
• One measure of the quality of the water in
lakes, rivers, and streams is the total amount
of solids dissolved in the water. High amounts
of dissolved solids can indicate poor water
quality. The same is true for drinking water.
Methods:
• Gravimetric method.
• Electrical Conductivity.

17. Gravimetric method.
• Gravimetric means "by weighing". Balances
require gravity to weigh something. You will
weigh the total dissolved solids after water is
boiled away. This will be done using just one
water sample.
Procedure:
• To measure TDS using this method, the water
sample is first passed through a filter that blocks
anything bigger than 2 microns ( 2 micrometers
or 2 millionths of a meter).

18. •
•
This ensures the test measures dissolved solids not solids
suspended in the water. Such things as sediment or specks of
plant material are filtered out and therefore not counted in
the "total dissolved solids“
A certain amount of the filtered water is then weighed out
and the water is boiled away leaving the dissolved solids
behind as a solid residue. This residue is weighed. This is
called the gravimetric method because a balance is used.
Balances need gravity to find the mass. So that's why it's
called a gravimetric method.