A large number of Canadians rely on water wells to provide them with their everyday water supply. What exactly are water wells made of? While many of us take our drinking water for granted, we forget how much goes into construction a water well. Most water wells obtaining groundwater for household use are comprised of many materials, with three being the most crucial.
The 3 most important materials needed to build a water well:
- Well Casing
Modern household wells are lined with sturdy steel piping or well casing. Other common materials or older well casing may be made from black or galvanized steel or concrete. The well casing is what keeps the well open and serves as the pathway for bringing up water from the earth to the surface. It’s usually around 4 to 6 inches in diameter. It prevents any soil, dangerous contaminants, leakage from surrounding formations, and rock from entering the well.
If a well is made using the rotary drilling method, there will be a space in between the bare hole and the well casing, called the annular space. Leaving the annular space open means risking contaminants entering the well. Grout, which is a unique mixture of cement, bentonite, or concrete, is used to fill in the empty areas. To ensure a well is fully sealed, the grout should be pumped into the well’s annular space. A grout pipe or tremie pipe is the best way to ensure the grout is reaching all the way down to the bottom of the annular space between the casing and the borehole. Grout should be continually poured into the gap until it comes to the surface.
- Well Screen
A well screen is usually found at the bottom of the casing and is essential for keeping sand and gravel out of the well. A well screen works like a sieve or strainer for the water well. Water can move through the screen freely while it catches any sand and gravel that may be trying to make its way into the water supply. Screens can be made from a few different materials, the most common today being stainless steel and slotted PVC pipe. The size of the screen will depend on the size of the unwanted particles trying to enter the well. Many water well owners will use a gravel pack as well. It’s placed around the side of the screen, between the screen and the borehole wall, or outside of the well screen. Gravel packs are best for keeping fine sediment, like sand, from clogging the filter.