If customers have proper storage, the water pipeline has a greater economy and safety. Storage adds reliability to the water supply in the event of reduced water pipeline flow due to accident or normal maintenance. Properly designed storage facilities can also reduce the instant demand on the water source and thereby reduce the size and cost of pipes, pumps and related infrastructure.
For water pipelines with storage, each residential connection should have a storage tank such as a cistern that is sized for at least two days of future average day water demand. The typical size of water storage for in-house use with a family of three persons is 1.4 m
3 (300 imperial gallons).A cross-connection is any point in a water pipeline where chemical, biological or radiological contaminants may come into contact with water intended for human consumption or hygienic use. During a backflow event, these contaminants can be drawn or pushed back into the water system. Strict precautions must be taken in the design of water pipelines to prevent the entrance of contaminating materials into the pipeline supply of water for hygienic use or human consumption use. The water pipeline design shall layout backflow prevention devices (BPD) to eliminate cross-connection hazards.
An example of a cross-connection hazard is the backflow of pesticides into drinking water while spray tanks are filled by a customer at a yard hydrant fed by a line experiencing negative pressure.
A BPD will be installed at every point of cross-connection to prevent contaminated water from entering the water pipeline.
In the interests of increased safety and liability reduction, designers may chose to add a backflow preventer at mainline locations where pipe ownership changes. BPD must be installed according to manufacturer’s instructions, typically in a warm, dry area and according to any other relevant plumbing codes, health codes and other regulations. Manhole BPD design and installation must prevent flooding problems and cold temperatures which may interfere with correct operation of the BPD. The service connection BPD may be located in the water users basement or other heated room as close as possible to the service line entrance point, while maintaining easy access for servicing. Ensure the BPD is not subject to flooding, cold or other adverse conditions.
With a basement BPD or similar service line BPD, if any other line or object withdraws water from the service line, ensure the withdrawal point is downstream of the basement BPD and the withdrawal point has suitable BPD, regardless of the volume of water withdrawn. As an example, a yard hydrant should be supplied typically by a line run from after the basement BPD to the hydrant which also has an air gap BPD. The basement BPD (if a DCVA) is not a sufficient BPD for a yard hydrant and the basement BPD may protect only the service line and not the residence, therefore the designer must incorporate an air gap BPD into the yard hydrant. Do not source water for yard hydrant lines from before the service line BPD because of the potential for easy bypassing or removal of the yard hydrant air gap device. The same applies to large-scale withdrawal such as a livestock watering operation.
Interconnecting a private water supply system to the water pipeline is not acceptable. Regulation of backflow prevention at a private residence is the jurisdiction of Saskatchewan Health (SH). SH must be contacted for required permits and inspections.
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