Journal of Water Resource and Protection, 2012, 4, 746-749 Published Online September 2012 (
Uncontrolled Drilling: Exposing a Global Threat to
Groundwater Sustainability
Romain Chesnaux
Department of Applied Sciences, Université du Québec à Chicoutimi, Chicoutimi, Canada
Received June 9, 2012; revised July 12, 2012; accepted August 24, 2012
Untold numbers of boreholes are drilled into the earth’s crust every year. Most constitute a potential threat to ground-
water quality by creating a preferred pathway for contaminant migration. Some solutio ns, including “well-poo ling”, are
proposed to better protect groundwater resources through the efficient management of boreholes.
Keywords: Groundwater Resources; Contamination; Drilling; Well-Pooling
I recently attended GeoHydro2011 in Quebec City, Can-
ada, a conference on groundwater resources. I spent
some time asking my hydrogeologist colleagues a few
simple questions: In your estimation, how many wells
have been drilled in the world? No one knows. In Canada?
No one knows. If one wan ted to determine th e number of
wells drilled in Canada (including for geotechnical, oil
and gas, water, etc. purposes), which government body
or professional association should be consulted? None
among my colleagues, all specialists in groundwater re-
source management, could provide an answer. Extensive
research has led me to conclude that comprehensive re-
gional or national listing s of all boreholes do not exist.
Every day, hundred s, even thousands, of boreholes are
drilled in the earth’s crust. Drilling is occurring in all
parts of the world: in the mountains, in the wilderness, in
the far North, in cities, in suburbs, in the countryside, in
the rainforest, in the deserts. Farmers and country resi-
dents are hiring private drilling contractors for their water-
supply wells. Petroleum companies are drilling for oil
and gas (sometimes kilometres deep). Exploration com-
panies and mining conglomerates are drilling for miner-
als. Municipal governments are drilling to supply their
populations with drinking water and monitor its quality.
Universities are drilling for groundwater research. Engi-
neering consulting firms are drilling for geotechnical
projects. Construction companies are drilling to build
bridges, roads and buildings. Most drilling is motivated
by the exploitation of non-renewable (oil and gas) and
renewable (groundwater, geothermal) resources.
Drilling can be considered as a wild (uncontrolled) ac-
tivity. Little authority is ex ercised ov er the act of drillin g,
the quality of borehole seals or the management of wells
on a local, municipal, provincial, national or global level.
Today, it seems, holes can be drilled in the ground with-
out anyone having to answer to the consequences.
Every time a borehole is drilled in the earth, a pathway
of vulnerability is created with a po tential for contamina-
tion and degradation of the groundwater resource [1-4].
Groundwater presents a contradictory situation: it is
prized when it has been protected from human activity on
the surface, but the very act of extracting it can contami-
nate the water or alter the underground environment that
protects it. Approximately 2 billion people worldwide
rely on aquifers for their drinking water supply [5].
Drilling into the subsurface can create hydraulic con-
nections between contaminated surface water and the
pristine underground water. These connections become
preferential pathways for cross-contamination, which is
the infiltration of surface contaminants into deeper (clean)
aquifers [2,6-8]. When a borehole is drilled for purposes
of drinking water extraction or monitoring, the usual
practice consists of sealing the borehole to prevent sur-
face contaminants from infiltrating through the annular
space between the borehole wall and the casing [5]. Even
though the practice of sealing a borehole is recom-
mended or locally regulated to prevent cross-contami-
nation, it is estimated that two-thirds of the wells world-
wide may be improperly sealed [5]. Considering the lack
of regulations on the quality of drilling methods and
equipment, the risk of contamination of groundwater sy-
stems is likely to increase. Existing techniques for veri-
fying and restoring borehole seal quality are extremely
cost-intensive and rarely applied in practice [9-11]. When
boreholes are drilled for purposes other than drinking
water, such as in mineral or gas exploration, practices are
opyright © 2012 SciRes. JWARP
even less regulated. Those boreholes are most often left
open and not properly filled. A large number of aban-
doned or orphan wells likely exist that have not been
filled or properly decommissioned [12]. These boreholes
are future contaminant leaks waiting t o ha p pen [5].
Rarely is permission required or sought before a bore-
hole is drilled. Many boreholes are drilled with no fore-
knowledge of the local conditions or the vulnerability of
the underlying aquifers. The qualifications of the people
and the quality of the practices, techniques and equip-
ment used for drilling boreholes are not sufficiently
regulated or controlled. Once a borehole is drilled, few
laws and regulations serve to register its location and
control its quality, integrity, use, lifespan and adequate
decommissioning once it is no longer of use.
The unfortunate event that occurred in 2000 in the
county of Walkerton in Ontario, Canada sadly illustrates
the consequences of cross-contamination between sur-
face water and groundwater in the vicinity of pumping
wells used for a municipal water supply [13,14]. These
contaminations had severe consequences on human
health; cases of deaths were reported due to the infiltra-
tion of E. coli bacteria into the city’s drinking water.
The vulnerability of aquifers can be measured and
mapped on a regional level using well-known tools. The
most widely used groundwater vulnerability mapping
method is known as DRASTIC [15], which uses hydro-
geological factors to identify areas where groundwater is
most vulnerable and where there is greatest potential for
groundwater contamination. The DRASTIC method,
however, does not take into account the existence of
boreholes. This is a significan t weakness, since boreholes
constitute a major contributor to the vulnerability of aq-
What will be the impact of uncontrolled drilling on
groundwater, especially in areas where the density of
boreholes is high? Nothing less than the endangerment of
the availability, quantity, quality, and sustainability of
drinking water supply for everyone, as well as the in-
creasing cost of clean water, in the face of rising demand
and need for the resource. New human settlements
spreading to previously uninhabited areas may find that
their potential reserves o f groundwater have already been
jeopardized by exploratory drilling. Exploratory drilling
is increasing in areas that are being developed, especially
in newly accessible Arctic zones where the ice pack is
withdrawing due to climate change. Paradoxically, these
areas will later be the site of human settlements with
their requisite need for drinking water. Pristine aquifers
may be already irrevocably contaminated by the time
new settlers arrive.
In all these situations, the lack of political will, laws,
regulations, control methods and database management
that are exercised when boreholes are drilled will have
both immediate and long-lasting repercussions on the
quality, accessibility and sustainability of groundwater.
Protecting the subsurface water resource and ensuring its
sustainability should be a major political and environ-
mental objective, and will require a concerted effort on
many fronts. Experience has shown that the occurrence
of borehole leakage decreases when regulations for well
construction, operation and monitoring are improved [12].
The following recommendations represent an outline of
measures which could be undertaken, some of which are
1. Raise awareness of the groundwater res ource
a) Educate the public.
b) Train engineers, technicians and other professionals
to be more aware of environmental risks arising from
incorrectly drilled boreholes and improper seals.
c) Legislate the requirement for all municipal, local,
and regional public governments to maintain a subsur-
face water management program.
2. Limit the number of boreholes drilled into the
earth. Governments should better control the drilling
activities that are occurring on their territories.
3. Institute and enforce regulations at a national,
regional and municipal level for drilling, completion
and abandonment of wells, regardless of their pur-
a) Permission should be required and obtained from a
relevant authority before drilling any hole in the ground,
even on private property.
b) Reporting the existence of all boreholes and sharing
the data must be required and enforced by law.
c) All boreholes should be georeferenced in a ground-
water database.
d) Personnel involved in boreh ole drilling should have
proper training and certification. Private drilling con-
tractors should be certified and should be required to
properly document their work.
e) New regulations and policies, as well as best man-
agement practices, should be implemented whereby all
boreholes drilled for the purpose of water extraction must
be protected by a wellhead protection area (e.g. no cattle
grazing around wells, no human activity with potential
for waste contam ination, etc.).
f) The data provided by all contributors to a borehole
database should be controlled for quality by a competent
g) Orphan wells and boreholes that have been aban-
doned or are no longer active must be properly filled,
protected and documented.
4. Well-pooling and community involvement: Car-
pooling owes its success to the fact that it not only helps
the environment, it also helps individuals save money.
Well-pooling can do the same. Everyone needs water,
but not everyone needs to have a well on their property.
Copyright © 2012 SciRes. JWARP
Municipalities could incite residents to share existing
wells or create partnerships in new wells. Communities
also need to share in the responsibility for preserving
their underground water resource, possibly by managing
their regional borehole geodatabase.
5. Compile, map and mainta in data bases that record
the groundwater resource and all regional boreholes [16].
These data can then be used to locate and measure dif-
ferent levels of vulnerability. Groundwater flow and
transport numerical models, when properly calibrated
and validated, can be used as a tool for predicting the im-
pact of residential, agricultural and industrial develop-
ment on groundwater. Databases can be used as a foun-
dation to institute local, regional and national groundwa-
ter management plans. However, databases will only be
useful if all drillers share borehole data as required by
law (see point 3b).
6. Prevent cross-contamination of aquifers caused
by leaking borehole seals, by ensuring the proper design
and construction of wells. The problems generated by
faulty borehole seals are much greater than the small
effort required to prevent them. A faulty seal is difficult
to detect and remediating the consequent contamination
is expensive, often beyond the means of local well-owners
or even municipalities. Frequently, costly water treat-
ment procedures are employed to decontaminate drinking
water, whilst a p roperly drilled boreh ole would have p re-
vented the problem [5].
7. Develop better scientific methods and institute
higher standards when measuring the vulnerability of
aquifers which take into account not only a complete
inventory of boreholes in a given region, but also their
integrity. Regulations must be instituted that make it
mandatory for engineers, geoscientists and other profes-
sionals to take into account the cumulative effects of
multiple boreholes when preparing aquifer vulnerability
reports for municipalities or governments.
8. Control the quantity and location of boreholes
drilled in remote areas. This is urgent. Before ground-
water is jeopardized in wilderness areas on a very large
scale, governments and environmental associations need
to act. Much political will and decision-making will be
needed to prevent the contamination of groundwater in
the remaining pristine wilderness areas of the planet.
Uncontrolled drilling is incompatible with sustainable
water management. To protect the planet’s renewable
supply of clean water, we may be obliged to control and
manage the holes that we drill into the earth. This implies
a responsibility on the part of all political and social
groups, from the individual resident all the way to legis-
lative bodies. Many concrete actions can be realistically
implemented in the immediate future, such as improving
drilling practices, registering boreholes and instituting
well-pooling, to help ensure a genuin e long-term ground-
water sustainability.
The author acknowledges the financial support of the
National Sciences and Engineering Research Council of
Canada (NSERC individual research grant). Grateful
thanks are expressed to Ms Josée Kaufmann for editorial
collaboration. Thanks are also extended to Dr. John W.
Molson and Dr. Gilles Wendling for their valuable com-
ments, which greatly improved the original manuscript.
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