Borehole Water
FREQUENTLY ASKED QUESTIONS
WHAT IS BOREHOLE WATER?
Rainwater permeates rocks and collects as ground water in natural, underground reservoirs called aquifers. It can take months or even years for the water to reach aquifers from the surface. The stratum through which the water passes determines the raw water characteristics. To abstract this water, boreholes are sunk as far as 120 metres into the rocks. Water is pumped to the surface, treated and distributed to consumers. Borehole water often has low total suspended solids (TSS), bacteriological and organic content but has high total dissolved solids (TDS), temporary hardness and possible iron, manganese and nitrite contamination.
WHAT QUALITY DOES BOREHOLE WATER NEED TO MEET?
Private water supplies from boreholes must be wholesome as required by The Private Water Supplies Regulations 1991. Information on your water private supply is available from your local authority, and general information is available from the Drinking Water Inspectorate.
IS SAMPLING REQUIRED?
Yes, the local authority is responsible for carrying out the many samples needed to ensure water quality (maximum charges do apply). The specific interval and type of sampling is dependant upon the use of the water and the number of properties / people supplied. A supply can be Category 1 (A to E) or Category 2 (1 to 5). Frequencies of sampling for specific parameters range from monthly to annually. The fifty-six parameters for analysis are listed in Schedule 2, Tables A to E of The Private Water Supplies Regulations 1991.
WHAT TREATMENT IS REQUIRED?
Initial sampling will highlight the treatment programme needed to improve the quality of borehole water to meet The Private Water Supplies Regulations 1991. Treatment can range from simple filtration or pH adjustment, to specific filters, reverse osmosis and disinfection.
WHAT ABOUT LEGIONNAIRES’ DISEASE?
The Approved Code of Practice and Guidance L8, “Legionnaires’ Disease – The Control of Legionella Bacteria in Water Systems” applies, as for water direct from the mains supply.
CAN I DRINK BOREHOLE WATER?
The Drinking Water Inspectorate advise that water from boreholes can be safe to drink, providing the sampling indicates that the water meets the specific parameters, and if softened or desalinated the levels of alkalinity and hardness are not below the minimum specified (Schedule 2, Table E of The Private Water Supplies Regulations 1991). Once water enters the building, the Drinking Water Inspectorate advice regarding drinking water from storage tanks applies (see bulletin ‘Drinking Water’).
