Whats the best choice for safe water supply?
WATER & WASTE

Whats the best choice for safe water supply?

When it comes to the pipes used for drinking water supply, there are a few options available, with galvanised and PVC pipes being two of the most common. But which one is the better choice? Choosing the ideal pipe for a construction project, especially for water supply, is a complex proce...

When it comes to the pipes used for drinking water supply, there are a few options available, with galvanised and PVC pipes being two of the most common. But which one is the better choice? Choosing the ideal pipe for a construction project, especially for water supply, is a complex process that involves various factors. These include the strength and water-carrying capacity of the pipe, its life and durability, transportation costs, jointing process, and maintenance and repair requirements. Each of these aspects must be carefully considered to ensure that the chosen pipe is fit for purpose and meets the project's specific needs. Choosing right Galvanised iron pipes (GI pipes) and plasticised polyvinyl chloride pipes (PVC pipes) are most commonly used for internal plumbing systems. BO Prasanna Kumar, Joint Managing Director, DesignTree Service Consultants, compares the two across various parameters: Durability: PVC pipes are more durable compared to GI pipes as GI pipesare not corrosion-resistant and will eventually rust. Bacterial growth: Bacterial growth in PVC pipes is low compared to GI pipes. Ease of installation: PVC pipes can easily be installed through cold welding. GI requires more man hours to install and, if not done correctly, can lead to breakage and leakage issues. Cost-effectiveness: Having a PVC plumbing system is a cost-effective affair with savings on extra fittings, loops, anchors, insulation and labour.Further, determining the type of pipe best suited for a construction project is crucial. “Quality of water is the most important factor for selecting the piping material,” opines Minesh Shah, Director, Aqua Utility Designs & Management.“Location of the project also plays a major role in material selection; i.e., Mumbai/Goa weather (humidity) is different to Delhi/Ahmedabad (dry and hot) weather. The choice needs to be made depending on the type of project –residential, commercial, hotel, hospital, institutional, luxury villa – and assessing if it is low rise, high rise, a super tall building or land development. Requirements of water pressure (design pressure) in the system also play an important role in material selection.” For his part, Sharat Rao, Managing Director, Engineering Creations Public Health Consultancy, says,“It is important to understand the type of project while selecting the pipe.Is it a luxury building, an affordable housing building or an SRA building?In the case of an SRA building, the preferred choice would be normal PVC pipes.” As for luxury construction, he recommends stainless steel pipes and composite piping that are more expensive but more efficient. The height of the building also plays a role in determining the piping to be used. “It is important to ensure that the piping can withstand higher pressures, especially in the case of high rises.” Maintenance and repair Irrespective of the pipe material, several precautions need to be taken for installation of pipes. “All pipes and fittings shall run in wall chase, ceiling or as specified,” explains Shah. He further mentions that where it is specified to conceal the pipes, chasing may be adopted for pipes fixed in the shafts and ducts, and there should be sufficient space to work on the pipes with the usual tools. Further, as far as possible, pipes may be buried for short distances provided adequate protection is given against damage and, where required, special care is to be taken at joints. In case the pipe is embedded in walls or floors, it should be painted with anticorrosive bitumastic paints of approved quality, in case of GI pipes. Under the floors, the pipes shall be laid in layer of sand filling. Also, piping shall be properly supported on, or suspended from, stands, clamps and hangers as specified and required.Adequately designed brackets, saddles, anchor, clamps and hangers shall be provided to ensure structural stability(see box for more). Maintenance &repair Minesh Shah, Director, Aqua Utility Designs & Management, adds to his list of precautions to be considered while installing pipes. Pipe hangers and supports shall be provided as per the standards and manufacturers’ guidelines. All pipes shall be accurately cut to the required size in accordance with relevant BIS codes and burrs removed before laying. Open ends of the piping shall be closed as the pipe is installed to avoid entrance of foreign matter. Where reducers are to be made in horizontal runs, eccentric reducers shall be used for the piping to drain freely. In other locations, concentric reducers may be used. All buried GI pipes shall be cleaned and coated with two coats of bitumen and then wrapped with two layers of 400 microne polythene sheet coating. All water supply systems shall be flushed before testing and tested to a hydrostatic pressure test of atleast one-and-a-half (1.5) times’ pressure for a period of not less than eight hours. All leaks and defects in joints revealed during the testing shall be rectified and approved at site with a retest. The system may be tested in sections; such sections shall be entirely retested on completion. In addition to the sectional testing carried out during construction, the contractor shall test the entire installation after connections to the overhead tanks, pumping system or mains. Leakages, if any, shall be rectified and all defective materials in the system shall be replaced. Before commissioning the water supply system, the contractor shall arrange to disinfect the entire system in a proper manner as specified in the codes and standards. The pipework shall be thoroughly flushed before supply is restored. For proper planning for repair work, it is necessary to assess the probable causes of failure.Kumaroutlines some factors to be considered to ensure pipe protection from damage or failure, including handling and storage of pipes, laying of pipeline, jointing of pipes, characteristics of soil, excessive temperature changes, internal pressure, aggressive water and galvanic action. Also emphasising upon the repair action plan for a pipeline, he lists: Detection of pipe failure: inspection of site; notification of interruption in water supply and related issues; location and demarcation; repair planning; repair work: selection of most appropriate method for repair; testing of ‘dry’ repair; restoration; completion; hygiene; and notice of restoration and completion. Regulations and standards There are certain regulations and standards that need to be followed when using GI or PVC pipes. One needs to follow IS 10500, 2012 to ensure drinking water quality standards, according to Shah, and piping materials must be based on the same. Proper treatment of water shall be taken up in case the quality of water does not comply with IS:10500, 2012. “Moreover, IS: 1239 for GI pipes and IS:4985 for PVC pipes for potable water application should also be adhered to,” he adds. Adding to the list of IS codes for water supply systems, Kumar lists: IS 15778:2007 - Specification for chlorinated polyvinyl chloride (CPVC) pipes for potable hot and coldwater distribution system IS 28:2005 - Specification for composite PEX-AL-PEX HOT and PE-AL-PE COLD water distribution system IAPMO IS 3:2003 - Specification for copper plumbing tube, pipe and fittings. Two things that govern the market today are constructing at a faster pace and costs, in Rao’s view. In terms of costs, he specifies that GI is 30-40 per cent more expensive than PVC pipes. “Plus, GI pipes are heavier in weight and manoeuvrability is cumbersome.” He would prefer a stainless-steel pipe, else a PVCpipe, for drinking water. “The stainless-steel pipe comes at a premium but it’s worth the spend because it is long lasting. The cost is more than two times than that of PVC– depending on if it is being sourced from an Indian manufacturer or a foreign one.” In the end, delivering high-quality water should be the top priority. We agree. Pipe characteristics &usage BO Prasanna Kumar, Joint Managing Director, DesignTree Service Consultants, shares pipe characteristics and uses for various types of pipes in a water supply distribution system. Chlorinated polyvinyl chloride (c-PVC) pipes & fittings: Safety of potable water and long-term reliability Resistance to corrosion, tuberculation, deposits Chlorine and chloramine resistance Lightweight and easy to transport Available in a wide range of sizes Noise and water hammer resistance Durability and toughness to survive jobsite installations UPVC pipes and fittings: Extremely resistant to chemicals, abrasion and corrosion High strength, good flexibility and good air permeability Wide range of fittings Easy to install and maintain Stable performance through long-term usage Eco-friendly Lightweight Flexible and versatile PEX pipes & fittings: Durable material Environment-friendly Cost-effective and quickly installable Flexibility and quicker installation Durable and freeze-resistant Resistance to corrosion Composite pipes: Corrosion-resistant Inert to acids and chemicals Smooth flow characteristics that can handle a range of temperature Copper pipes & fittings: Durable Lightweight and can be bent easily Donot contaminate the water Can withstand both hot and cold water Recyclable, so less harmful to the environment Fire-resistant GI (galvanised iron) pipes & fittings: Galvanising is lower in first cost than many other commonly specified protective coatings for steel Less maintenance and lowest long-term cost Long life Polybutylene (PB) pipes and fittings: Flexibility Ease of installation Resistance to freezing Affordable - SHRIYAL SETHUMADHAVAN

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