Water well basics

A well gets its water from an underground source called groundwater. Ground water is a resource found under the earth’s surface. Most ground water comes from rain and melting snow soaking into the ground. Water fills the spaces between rocks and soils, making an “aquifer”. Ground water, its depth from the surface, quality for drinking water, and chance of being polluted, varies from area to area. Generally, the deeper the well, the better the ground water. The amount of new water flowing into the area also affects ground water quality.

Hacking at the ground with a pick and shovel is one way to dig a well. If the ground is soft and the water table is shallow, then dug wells can work. They are often lined with stones to prevent them from collapsing. They cannot be dug much deeper than the water table -- just as you cannot dig a hole very deep when you are at the beach... it keeps filling up with water!

Driven wells are still common today. They are built by driving a small-diameter pipe into soft earth, such as sand or gravel. A screen is usually attached to the bottom of the pipe to filter out sand and other particles. Problems? They can only tap shallow water, and because the source of the water is so close to the surface, contamination from surface pollutants can occur.

Most modern wells are drilled, which requires a fairly complicated and expensive drill rig. Drill rigs are often mounted on big trucks. They use rotary drill bits that chew away at the rock, percussion bits that smash the rock, or, if the ground is soft, large auger bits. Drilled wells can be drilled more than 1,000 feet deep. Often a pump is placed at the bottom to push water up to the surface.

Domestic water wells

Safe, clean water is one of the most vital resources we have for drinking, cooking, bathing and cleaning. The Township tests the Municipal drinking water supplies weekly, to ensure they are safe. But it is a homeowner’s responsibility to test their own well water. Laurentian Valley Township has approximately 4,500 private water wells. Most of these wells are not tested for coliform bacteria and other contaminants on a regular basis. Many of these contaminants can cause sickness in people who drink, bathe, or cook with the water.

These days we are hearing and reading about situations where the quality of water is not good enough for normal uses. Bacteria and other microorganisms have gotten into drinking-water supplies, causing severe illness and even deaths. Chemical pollutants have been detected in streams, endangering plant and animal life. Water quality has become a very big concern. If we are not diligent, the quality of our water supply will suffer.

As a private water well owner, it is your duty to understand the basics of well maintenance. It is also the law, Regulation 903 of the Ontario Water Resources Act sets out your obligations as a private water well owner.

As a responsible well owner, you need to carry out a regular program of well maintenance. Taking care of your well is a three-step process.

  1. Protect your well water at the ground surface by avoiding, eliminating or reducing contaminants.
  2. Inspect your well regularly and keep your well in good running order.
  3. Test your well water regularly and respond to contamination problems.

 Domestic water well definitions

 Annual sealer
When a well is drilled, the hole in the ground is larger than the well casing. This gap, the annular space, is filled with a water tight sealant, usually bentonite. Bentonite does not crack or shrink in the ground. Regulation 903 prescribes the minimum depth of the sealant.
An underground formation or group of formations in rocks and soils containing enough ground water to supply wells and springs.
Also called back siphonage, a reverse flow in water pipes. A difference in water pressures pulls water from sources other than the well into a home’s water system. For example, waste water or flood water.
Microscopic living organisms; some are helpful and some are harmful. “Good” bacteria aid in pollution control by consuming and breaking down organic matter and other pollutants in septic systems, sewage, oil spills, and soils. However, “bad” bacteria in soil, water, or air can cause human, animal, and plant health problems.
 Coliform bacteria
A group of bacteria predominantly inhabiting the intestines of humans or animals but occassionaly found elsewhere. The presence of this bacteria in water is used as an indication of faecal contamination. (contamination by human or animal waste)
 Confining layer
Layer of rock that keeps the ground water in the aquifer below it under pressure. This pressure creates springs and helps supply water to wells.
Anything found in water (including microorganisms, minerals, chemicals, radionuclides, etc.) which may be harmful to human health. 
Any actual or potential connection between a drinking (potable) water supply and a source of contamination.
 Heavy metals
Metallic elements with high atomic weights, such as, mercury chromium cadmium, arsenic, and lead. Even at low levels these metals can damage living things. They do not break down or decompose and tend to build up in plants, animals, and people causing health concerns. 
 Hydrologic cycle
Is the natural process of rain and snow falling to earth and evaporating back to form clouds and fall again. The water falling to earth flows into streams, rivers, lakes and into the soil collecting to form groundwater.
Leaching field
The entire area where many materials (including contaminants) dissolve in rain, snowmelt, or irrigation water and are filtered through the soil.
Also called microbes. Very tiny life forms such as bacteria, algae, diatoms, parasites, plankton, and fungi. Some can cause disease.
Plant nutrient and fertilizer that enters water supply sources from fertilizers, animal feed lots, manures, sewage, septic systems, industrial wastewaters, sanitary landfills, and garbage dumps.
In the forms of nitrate, nitrite, or ammonium, is a nutrient needed for plant growth. About 78% of the air that we breathe is composed of nitrogen gas. Some forms of nitrogen are commonly deposited in acid rain. Although nitrogen is abundant naturally in the environment, it is also introduced through sewage and fertilizers.
Is an essential element for plant life, but when there is too much of it in water, it can speed up eutrophication (a reduction in dissolved oxygen in water bodies caused by an increase of mineral and organic nutrients) of rivers and lakes.
Small single-cell animals, usually microscopic, that are larger and more complex than bacteria. (including amoebas, ciliates and flagelates)
A colourless, odourless naturally occurring radioactive gas formed by the breakdown or decay of radium or uranium in soil or rocks like granite. Radon is fairly soluble in water, so well water may contain radon.
A material with an unstable atomic nucleous that spontaneously decays or disintegrates producing radiation. Distinct radioactive particles coming from both natural sources and human activities. Can be very long lasting as soil or water pollutants.
Recharge area
The land area through or over which rainwater and other surface water soaks through the earth to replenish an aquifer, lake, stream, river, or marsh. Also called a watershed.
Saturated zone
The underground area below the water table where all open spaces are filled with water. A well placed in this zone will be able to pump ground water.
Unsaturated zone
The area above the ground water level or water table where soil pores are not fully saturated, although some water may be present.
Submicroscopic disease-causing organisms that grow only inside living cells.
The land area where water soaks through the earth filling an underground water supply or aquifer. It is also called a recharge area.
Water table
The line below which the ground is saturated or filled with water and available for pumping. The water table will fall during dry seasons. A well can pump water from either the saturated zone or an aquifer. Wells must be deep enough to remain in the saturated zone.
Well cap
A tight-fitting, vermin-proof seal designed to prevent contaminants from flowing down inside of the well casing.
Well casing
The tubular lining of a well. Also a steel or plastic pipe installed during construction to prevent collapse of the well hole.
The top of a structure built over a well. Term also used for the source of a well or stream.
Well pit
Common on wells constructed before 1985, the well casing was terminated below ground and an access pit such as well tiles were placed over and around the casing with a lid. This was done to protect the water lines from freezing.


MOECC - Water Well Records
  • If you are trying to locate a copy of the well record for your property you may be able to find it by using the Ministry's mapping tool. This map allows you to search and view well record information from reported wells in Ontario
  • Go to MOECC
Well Aware
  • A portal website for private well owners. Includes an online version of the Well Aware booklet.
  • Go to Well Aware
Ontario Ground Water Association 
  • This is a membership database that includes licensed well drillers and pump installers, manufacturers, suppliers, groundwater scientists and engineers.
  • Go to OGWA
Renfrew County and District Health Unit (RCDHU)
  • This website has more detailed information on sampling, testing and what to do if your well water is contaminated.
  • Go to RCDHU