The protection of water quality in drilled wells. The purpose of this Green Facts sheet is to assist people who rely on drilled wells for their water to achieve acceptable water quality. Improper well construction or the failure to carry out routine preventive maintenance on a well can result in contaminated water. In 2003, Ontario updated its regulatory requirements for water well siting, construction, maintenance and abandonment to better protect well users and groundwater resources. Ontario 's Wells Regulation (Reg. 903, under the Ontario Water Resources Act) requires well contractors and well technicians to be licenced by the Ministry of the Environment. The regulation also sets the minimum construction standards to which all well contractors, including private homeowners, must adhere. Although upgrading work can be done by a private well owner working on their own property, employing a licenced well contractor is strongly advised to ensure that proper minimum well construction standards are met and protection of the water supply is achieved. The regulation also states that "the well owner shall maintain the well at all times after the completion date in a manner sufficient to prevent the entry into the well of surface water or other foreign materials.

Factors contributing to the deterioration of drilled well water quality A poorly maintained or constructed well can result in the bacterial and/or chemical contamination of its water. One of the most common causes of contamination is foreign materials and surface waters in the immediate vicinity of a well having direct access into the well. In Ontario , drilled wells are constructed using a variety of drilling machines that produce holes of varying diameters, and are usually lined with a steel casing. Problems due to surface water contamination occur when the sealing around the outside or top of the casing is not watertight. Damage such as cracking of old cement grouting or corrosion can also allow surface waters to enter such a well. Wells in pits are particularly vulnerable because the pits can hold surface contamination directly over or around the casing for long periods of time. For that reason, the construction of well pits for new wells is no longer permitted in Ontario effective August 1, 2003. Indicators that sealing around the well casing may be inadequate and surface contamination may be gaining access to the well include: • presence of coliform bacteria in counts exceeding recommended limits set by health authorities; • changes in the appearance or physical quality of the water, such as turbidity, colour, taste or odour, especially after a rainstorm or snow melt; • rapid or large changes in the well water level, especially after a rainstorm or snow melt ; • cascading, seeping or stagnant water and/or staining inside the casing in a well pit; • the presence of biological material, such as animals, insects or roots, in a well pit; • unsealed or parted joints or cracks in the casing wall or cover; • a cracked or damaged well cap; • settlement of soils around the well casing at ground level or around the old well pit; • the casing is noticeably heaved or loose in its seal, or water is bubbling up around casing; • an absence of any sanitary well seal or vermin-proof or watertight well cap over the casing set at an appropriate height above land surface level; or • changes in the chemical quality of the well water detected through laboratory analysis.