How a Groundwater Impact Assessment Is Conducted: Step-by-Step Guide for Industrial Projects
A Groundwater Impact Assessment should not begin with groundwater modelling software.
It should begin with a much simpler question:
How much groundwater does the industrial project actually need, and what groundwater system will that withdrawal affect?
A credible assessment connects three separate sets of information:
the industrial project
the site's hydrogeology
the proposed groundwater abstraction
Only after these are understood should the consultant assess drawdown, surrounding groundwater users, recharge, cumulative stress and long-term groundwater response.
For projects falling under the applicable CGWA thresholds, the Central Ground Water Board currently requires an Impact Assessment Report and groundwater modelling study covering a 5 km radius around the project site and prepared through accredited groundwater professionals/institutions.
For industries, however, the technical value of the exercise goes beyond regulatory filing.
A good assessment should help answer:
Can the aquifer support the proposed abstraction?
Is the proposed groundwater requirement unnecessarily high?
How might groundwater levels respond?
Could neighbouring wells be influenced?
Is the impact likely to increase during dry years?
What monitoring should be installed?
What water-conservation or alternative-source measures are needed?
Will future industrial expansion remain feasible?
That is why groundwater impact assessment should be treated as an engineering decision study, not simply an attachment to an NOC application.
For the broader regulatory framework, see SARK's Groundwater Regulatory Intelligence for Industries in India.
Step 1 — Regulatory Screening Comes First
Before collecting data, establish why the assessment is being undertaken.
The project should identify:
exact site location;
applicable groundwater authority;
groundwater assessment-unit classification;
new or existing project status;
proposed groundwater abstraction;
number of abstraction wells;
project activity;
hydrogeological setting; and
current regulatory requirements.
CGWB currently requires mandatory impact assessment and groundwater modelling for projects proposing groundwater withdrawal above specified thresholds.
These include:
more than 100 m³/day in Over-Exploited, Critical and Semi-Critical assessment units;
more than 500 m³/day in Safe areas underlain by non-alluvium formations; and
more than 2,000 m³/day in Safe assessment units underlain by alluvium.
These thresholds should always be checked against the latest applicable rules before filing.
If you are unsure whether the project reaches this stage, first read:
When Is Groundwater Impact Assessment Required for an Industrial Project?
Step 2 — Establish the Exact Project Water Requirement
This is one of the most important stages.
An impact assessment should not blindly model whatever groundwater quantity appears in the DPR.
The proposed groundwater requirement should first be reconciled with the complete industrial water balance.
The assessment should identify:
Freshwater Sources
groundwater;
municipal supply;
industrial water supply;
surface water;
purchased water;
reclaimed water;
other authorised sources.
Major Water Users
process;
cooling towers;
boilers;
washing;
domestic use;
utilities;
horticulture;
product incorporation.
Wastewater Streams
process effluent;
sewage;
cooling blowdown;
boiler blowdown;
RO reject;
wash water;
condensate.
Recovery Opportunities
treated ETP water;
treated STP water;
condensate recovery;
process-water recycling;
RO recovery;
rainwater utilisation.
The groundwater model should ideally assess the minimum technically practical groundwater withdrawal, not an inflated demand created by inefficient plant operation.
This is why an Industrial Water Audit can be an important precursor to groundwater impact assessment.
Step 3 — Define the Study Area
For applicable CGWA impact assessments, the current framework specifies evaluation and modelling over a 5 km radius around the project site.
The study area should capture enough of the surrounding groundwater system to understand:
regional geology;
aquifer continuity;
groundwater levels;
nearby abstraction;
recharge;
surface-water interaction;
villages and settlements;
neighbouring industries;
irrigation wells;
other major groundwater users.
The purpose of the study boundary is not merely cartographic.
Groundwater does not stop at the factory boundary.
An industrial production well may influence groundwater beyond the company's land parcel.
Step 4 — Collect Existing Geological and Hydrogeological Information
The desk-study phase builds the initial conceptual understanding of the aquifer.
Typical sources may include:
CGWB publications;
State groundwater department reports;
aquifer maps;
geological maps;
groundwater-resource assessments;
rainfall records;
topographic information;
satellite imagery;
drainage maps;
previous borewell records;
groundwater-level data;
groundwater-quality information.
CGWB describes groundwater modelling as a tool for organising hydrological data, understanding system behaviour and predicting response to externally applied stresses.
But the model is only as good as the conceptual understanding behind it.
The desk study therefore tries to establish:
What aquifers exist, how are they recharged, how does groundwater move and where is groundwater already being withdrawn?
Step 5 — Understand the Geological Setting
The groundwater behaviour of an alluvial aquifer can differ substantially from that of hard rock.
Important geological factors can include:
lithology;
weathered zones;
fractured rock;
sand and gravel horizons;
clay layers;
confining formations;
aquifer thickness;
faults or structural controls.
CGWB notes that porous alluvial formations generally have relatively high specific yields, while groundwater occurrence in fissured formations is concentrated largely within weathered, jointed and fractured zones.
This is one reason the current CGWA framework uses different impact-assessment thresholds for alluvial and non-alluvial Safe areas.
Step 6 — Prepare an Inventory of Existing and Proposed Wells
The assessment should document the project's own groundwater infrastructure.
Typical information includes:
borewell identification;
latitude and longitude;
depth;
casing;
diameter;
aquifer tapped;
pump setting;
pump capacity;
operational hours;
discharge;
historical abstraction;
current status.
For existing factories, this inventory should be reconciled with:
groundwater NOC;
registered abstraction structures;
flow-meter readings;
production;
operating schedules.
The project should also identify important surrounding wells where data is available.
These may include:
industrial wells;
irrigation wells;
public-supply wells;
village wells;
observation wells.
Step 7 — Measure Groundwater Levels
Groundwater-level data provides one of the most direct indications of aquifer behaviour.
Measurements may include:
static water level;
pre-monsoon level;
post-monsoon level;
seasonal variation;
long-term groundwater trend.
For existing projects, historical monitoring is particularly valuable.
A single groundwater-level reading provides only a snapshot.
A time series can show whether the aquifer is:
stable;
recovering seasonally;
gradually declining;
strongly influenced by pumping.
CGWA's present framework also specifies observation-well/piezometer monitoring requirements for applicable industrial users and requires monthly water-level data to be submitted through the portal in specified cases.
Step 8 — Review Piezometers and Observation Wells
A production borewell is not always the ideal place to monitor regional groundwater response.
Pumping itself creates drawdown inside and around the well.
A separate piezometer or observation well can help track aquifer response independently of production pumping.
Under current CGWA guidelines, specified projects drawing groundwater above applicable thresholds outside designated industrial areas may require observation wells/piezometers. The guidelines also prescribe minimum separation between pumping wells and piezometers depending on alluvial or hard-rock conditions.
Where monitoring data exists, the consultant should correlate:
groundwater level
with
groundwater abstraction
rainfall
production
rather than interpret the level in isolation.
Step 9 — Conduct a Hydrogeological Field Survey
Desk data should be verified against conditions on the ground.
Field investigations may include:
site reconnaissance;
geological observations;
borewell inventory;
water-level measurement;
review of drainage;
inspection of recharge areas;
surrounding groundwater-user survey;
examination of existing RWH structures;
groundwater sampling.
Depending on site complexity, additional investigations may include:
geophysical surveys;
pumping tests;
slug tests;
aquifer testing;
water-quality analysis.
The purpose is to refine the conceptual understanding of the aquifer before modelling begins.
Step 10 — Conduct Pumping / Aquifer Tests Where Appropriate
A pumping test can provide important information about aquifer response.
A well is pumped at a controlled rate while groundwater-level changes are monitored.
The test can help estimate aquifer parameters such as:
transmissivity;
hydraulic conductivity;
storativity;
specific capacity.
These parameters influence how groundwater responds to sustained abstraction.
For example:
Two wells may each yield 30 m³/hour.
But one may draw from a thick, highly transmissive aquifer while the other obtains the same yield from a more limited fracture system.
Their long-term implications may be very different.
Step 11 — Assess Groundwater Quality
Groundwater impact assessment should not necessarily be restricted to quantity.
CGWA's regulatory objective expressly addresses groundwater sustainability in terms of both quantity and quality.
Typical groundwater-quality parameters may include:
pH;
electrical conductivity;
TDS;
hardness;
alkalinity;
chloride;
sulphate;
nitrate;
fluoride;
iron;
heavy metals;
project-specific contaminants.
Water quality matters for two reasons.
First, it determines whether groundwater is suitable for the intended industrial application.
Second, industrial activities should not create a contamination pathway into the aquifer.
Current CGWA guidelines prohibit injection of treated or untreated wastewater into aquifers and prescribe groundwater-protection measures for potentially polluting industries.
Step 12 — Assess Rainfall and Groundwater Recharge
Recharge is the other side of the groundwater balance.
Groundwater withdrawal cannot be interpreted properly without understanding how the system is replenished.
Assessment may consider:
long-term rainfall;
monsoon distribution;
soil;
geology;
infiltration;
drainage;
surface-water bodies;
land use;
recharge structures.
CGWB notes that rainfall contributes a major portion of India's replenishable groundwater recharge, but recharge conditions vary significantly according to geology and geography.
Rainfall should therefore not be treated as equivalent to groundwater recharge.
Step 13 — Examine Existing Groundwater Development
The project is rarely the only groundwater user in the area.
The assessment should examine surrounding abstraction from:
agriculture;
industry;
domestic supply;
commercial establishments;
public-water systems.
This is important because groundwater impact can be cumulative.
A project proposing 300 KLD may appear moderate when analysed alone.
But if several large groundwater users already abstract from the same aquifer, the combined stress may be much greater.
Step 14 — Develop the Conceptual Hydrogeological Model
Before creating a numerical groundwater model, the consultant should first create a conceptual model.
This represents an engineering interpretation of:
aquifer geometry;
geological layers;
groundwater table;
recharge;
groundwater-flow direction;
abstraction wells;
surface-water boundaries;
inflows;
outflows.
Think of it as the physical story of how groundwater behaves beneath and around the project.
Only after that story is credible should it be converted into a numerical model.
Step 15 — Build the Numerical Groundwater Model
For applicable projects, groundwater modelling allows the consultant to simulate the aquifer system mathematically.
CGWB describes groundwater models as tools capable of predicting the response of groundwater systems to externally applied stresses.
A model may represent:
aquifer layers;
hydraulic conductivity;
storage;
recharge;
rivers;
boundaries;
pumping wells;
groundwater flow.
The project abstraction is then introduced as a pumping stress.
The model calculates how the groundwater system may respond.
Step 16 — Calibrate the Groundwater Model
A model should not simply produce colourful contours.
It must be tested against observed groundwater conditions.
Calibration typically compares:
modelled groundwater levels
against
observed groundwater levels.
Parameters may be adjusted within technically reasonable ranges until the model adequately represents the actual groundwater system.
Calibration helps answer:
Does the model reproduce the groundwater behaviour that already exists?
Only then should predictive scenarios be trusted.
Step 17 — Simulate the Proposed Industrial Abstraction
Once calibrated, the model can simulate future pumping.
Typical scenarios could include:
Existing Condition
Current groundwater abstraction.
Proposed Project
Current abstraction + proposed industrial pumping.
Expansion Scenario
Higher future withdrawal after production expansion.
Reduced Groundwater Scenario
Water conservation and reuse reduce fresh groundwater demand.
Stress / Dry-Year Scenario
Lower recharge or adverse groundwater conditions.
This is where the groundwater study becomes a decision tool rather than simply documentation.
Step 18 — Estimate Drawdown and Cone of Depression
When a well pumps groundwater, groundwater levels around the well decline.
This creates a cone of depression.
The assessment should evaluate:
predicted drawdown;
spatial extent;
overlapping influence of multiple wells;
potential effect on surrounding users.
The most important question is often not:
Can this borewell produce 20 m³/hour?
It is:
What happens to the aquifer if it produces 20 m³/hour repeatedly for years?
Step 19 — Assess Impact on Nearby Groundwater Users
Groundwater does not recognise property boundaries.
The assessment should therefore evaluate whether project pumping could influence:
neighbouring industrial wells;
village supplies;
irrigation wells;
domestic users.
The level of detail should reflect project scale, hydrogeology and regulatory requirements.
For large groundwater withdrawals in already stressed areas, this can become a significant component of the overall assessment.
Step 20 — Evaluate Socio-Economic Implications
Groundwater withdrawal can have implications beyond the industrial site.
Potential issues include:
reduced well yields;
deeper pumping levels;
increased pumping energy;
agricultural impacts;
community drinking-water availability;
competition between groundwater users.
Current CGWA impact-assessment provisions explicitly refer to assessment of groundwater-regime and socio-economic impacts for qualifying projects.
Step 21 — Test Whether Groundwater Demand Can Be Reduced
This step is often underdeveloped in groundwater reports.
Suppose modelling suggests that the proposed abstraction creates significant drawdown.
The solution need not always be:
“Drill another borewell.”
Alternative scenarios should be evaluated.
For example:
300 KLD proposed groundwater
could become:
220 KLD after water-efficiency measures;
170 KLD after wastewater reuse;
140 KLD after condensate recovery and cooling optimisation.
The groundwater model can then assess the reduced-pumping scenario.
This directly connects groundwater modelling with Industrial Water Audit and Zero Liquid Discharge / high-recovery systems where technically appropriate.
Step 22 — Assess Rainwater Harvesting and Recharge Measures
Current CGWA guidelines require project proponents to adopt rooftop rainwater harvesting/recharge within project premises, subject to project and industry-specific conditions. Potentially polluting industries may instead need harvested rainwater to be stored for industrial use rather than introduced into the groundwater system.
A credible assessment should consider:
available roof area;
paved catchment;
rainfall;
runoff;
storage;
recharge suitability;
contamination risk;
hydrogeology;
safe overflow.
Recharge should not simply be assumed to exactly offset abstraction.
Step 23 — Develop the Groundwater Monitoring Plan
An impact assessment is predictive.
Monitoring determines what actually happens.
A monitoring plan may include:
abstraction flow meters;
piezometers;
groundwater levels;
water-quality testing;
rainfall;
groundwater abstraction;
production-linked water consumption.
A useful monitoring framework asks:
Did the aquifer respond as predicted?
If not, the groundwater-management strategy may need adjustment.
Step 24 — Develop Mitigation Measures
Depending on the findings, recommended actions might include:
Reduce Groundwater Withdrawal
Through water efficiency and recycling.
Change the Water-Source Mix
Introduce municipal, industrial or reclaimed water.
Improve Wastewater Reuse
Use treated water for appropriate process or utility duties.
Increase Condensate Recovery
Particularly in steam-intensive industries.
Optimise Cooling Systems
Reduce avoidable cooling-tower make-up.
Improve Rainwater Management
Storage, use or recharge where appropriate.
Improve Monitoring
Additional piezometers, meters or water-quality monitoring.
The assessment should lead to implementable engineering actions.
Step 25 — Prepare the Final Impact Assessment Report
The final report should bring all of the work together logically.
A robust industrial groundwater impact assessment may contain:
Executive Summary
Project Description
Project Water Requirement
Existing and Proposed Groundwater Abstraction
Study Area
Climate and Rainfall
Geology
Hydrogeology
Aquifer Characteristics
Groundwater-Level Data
Borewell Inventory
Groundwater Quality
Existing Groundwater Development
Recharge Conditions
Field Investigations
Pumping-Test Results
Conceptual Hydrogeological Model
Numerical Groundwater Model
Model Calibration
Predictive Pumping Scenarios
Drawdown Assessment
Nearby User / Cumulative Impact Assessment
Water Conservation and Reuse
Rainwater Harvesting / Recharge Strategy
Monitoring Plan
Mitigation Measures
Conclusions and Recommendations.
The exact structure should reflect the applicable regulatory framework and project circumstances.
What Makes a Groundwater Impact Assessment Credible?
A credible study has a clear chain of evidence:
plant water demand
→ groundwater requirement
→ aquifer characteristics
→ observed groundwater data
→ model
→ predicted impact
→ mitigation
→ monitoring
A weak report often does the opposite:
generic district geology
→ generic maps
→ software output
→ “no significant impact.”
The latter may look technical, but it does not necessarily demonstrate that the project's groundwater requirement has been adequately evaluated.
How Long Does the Assessment Take?
There is no universal duration because the required fieldwork depends on:
project size;
availability of historical data;
number of wells;
monitoring data;
hydrogeological complexity;
need for pumping tests;
modelling requirements;
seasonal information.
An operating factory with years of good groundwater and abstraction data may provide a stronger evidence base than a greenfield site with no historical monitoring.
The most efficient approach is therefore to assemble the existing technical docket before fieldwork begins.
What Documents Should the Industry Keep Ready?
A project preparing for groundwater impact assessment should ideally compile:
site layout;
coordinates;
land documents;
production details;
process description;
project water balance;
groundwater NOC, if existing;
borewell details;
borewell logs;
pump specifications;
groundwater flow-meter data;
monthly abstraction;
piezometer records;
rainfall data;
groundwater-quality reports;
ETP/STP details;
wastewater reuse;
rainwater-harvesting drawings;
expansion plans.
The stronger the data, the stronger the study.
New Project vs Existing Industry
The methodology differs slightly.
For a New Project
The emphasis is more predictive.
The consultant relies on:
baseline groundwater conditions;
surrounding wells;
aquifer parameters;
proposed abstraction;
modelling;
future scenarios.
For an Existing Industry
The consultant can compare prediction with operating history.
Useful evidence includes:
actual abstraction;
production;
water consumption;
groundwater levels;
rainfall;
borewell performance;
historical piezometer data.
That can provide a much stronger basis for renewal or expansion decisions.
Groundwater Impact Assessment Should Influence Project Design
One of the biggest mistakes is conducting the groundwater study after the project water system has already been frozen.
For a water-intensive greenfield development, the better sequence is:
site selection
→ groundwater screening
→ industrial water balance
→ hydrogeological assessment
→ groundwater-impact assessment
→ alternative water analysis
→ final water architecture
→ CAPEX approval
This approach can prevent expensive redesign later.
For broader industrial due diligence, see SARK's Project Assessment services.
How SARK Engineers & Consultants Approaches the Assessment
SARK's engineering approach integrates groundwater with the facility's wider water system.
Stage 1 — Regulatory and Project Screening
Identify groundwater category, jurisdiction, abstraction and assessment requirements.
Stage 2 — Industrial Water Balance
Establish realistic fresh-water demand after recovery and reuse.
Stage 3 — Desk Hydrogeology
Review aquifers, geology, groundwater levels, rainfall and surrounding conditions.
Stage 4 — Field Investigation
Verify borewells, levels, infrastructure, surrounding groundwater use and site conditions.
Stage 5 — Aquifer Assessment
Evaluate aquifer parameters, recharge and groundwater movement.
Stage 6 — Groundwater Modelling
Where applicable, simulate existing and proposed groundwater withdrawal.
Stage 7 — Impact Assessment
Evaluate drawdown, nearby users, cumulative stress and groundwater sustainability.
Stage 8 — Mitigation and Water Strategy
Integrate demand reduction, reuse, RWH, alternative supply and monitoring.
Stage 9 — Technical Report
Prepare the regulatory and engineering output appropriate to the project.
This methodology sits within SARK's wider Groundwater Regulatory Intelligence for Industries framework.
Frequently Asked Questions
What is the first step in a Groundwater Impact Assessment?
The first step should be project and regulatory screening followed by verification of the actual groundwater requirement. Modelling an inaccurate or unnecessarily high water demand produces an inaccurate project scenario.
How large an area is studied?
For projects falling under current CGWA mandatory impact-assessment requirements, CGWB specifies groundwater impact assessment and modelling covering a 5 km radius around the project site.
Does every Groundwater Impact Assessment require modelling?
Not every groundwater study necessarily requires a numerical model. However, current CGWA rules specifically require modelling for projects crossing the applicable impact-assessment thresholds.
What is groundwater model calibration?
Calibration compares simulated groundwater levels with observed groundwater conditions and adjusts technically defensible model parameters so that the model reasonably reproduces the actual groundwater system.
What is a cone of depression?
It is the lowering of groundwater levels around a pumping well caused by groundwater abstraction.
Is a pumping test part of Groundwater Impact Assessment?
It can be important where aquifer parameters need to be established or verified. The required investigation depends on the available data and hydrogeological conditions.
Why is an industrial water balance needed?
It determines whether the proposed groundwater abstraction represents the actual minimum freshwater requirement or whether reuse, recovery and efficiency could reduce it.
Can an existing industry's historic data improve the assessment?
Yes. Flow-meter readings, piezometer levels, rainfall, production and groundwater abstraction history can provide valuable evidence of actual aquifer response.
Regulatory Note
Information reviewed: August 2026
CGWB currently states that mandatory groundwater impact assessment and modelling applies to specified higher groundwater withdrawals, including more than 100 m³/day in Over-Exploited, Critical and Semi-Critical areas and higher thresholds in Safe alluvial/non-alluvial areas. The applicable regulations and jurisdiction should be verified at the time of each project.
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