Groundwater from depth and confined aquifers is usually microbially safe and chemically stable in the absence of direct contamination. Shallow or unconfined aquifers, however, can be subject to contamination from discharges or seepage associated with agricultural practices, on-site sanitation and sewage and industrial wastes.
Groundwater protection measures include:
General protection - Many problems stem from improper construction, maintenance, operation or abandonment. New groundwater sources, private wells and existing groundwater sources that have never been tested for contamination, should be tested for presence of microbiological, physical and chemical contaminants (particularly arsenic, nitrates/nitrites and fluoride).
Protection from agricultural contamination - Fertilizers and manure should be applied at an appropriate distance from groundwater sources and unconfined aquifers to avoid nitrates washing into groundwater. Manure piles should not be situated on hillsides above groundwater sources or within 100 m of the groundwater source. Wells should be sealed and flood-proofed and old wells should be properly sealed with a bentonite seal.
Protection from urban contamination - Septic systems must be monitored and maintained (pumped out every 3 to 5 years). Malfunctioning septic systems must be repaired.
Protection from salt water intrusion - In coastal regions, heavy withdrawals from aquifers can cause salt water from nearby ocean water to replace the freshwater in the emptying aquifer.
Water Service Authorities whose source water comes from aquifers should develop well protection plans in consultation with other authorities in order to address the risks of groundwater contamination.