There are different types of water pipes designed to transport water to choose from. The varieties include large diameter main pipes which supply entire towns, smaller branch lines that supply a street or group of buildings or small diameter pipes located within individual buildings. Materials commonly used to construct water pipes include cast iron, polyvinyl chloride (PVC), copper, steel or concrete. If the water is treated before distribution or at the point of use depends on the context. In well planned and designed water distribution netwoeks, water is generally treated before distribution and sometimes also chlorinated, in order to prevent recontamination on the way to the end user.
Types of pipes
Pipes come in several types and sizes. They can be divided into three main categories: Metallic pipes, cement pipes and plastic pipes. Metallic pipes include steel pipes, galvanized iron pipes and cast iron pipes. Cement pipes include concrete cement pipes and asbestos cement pipes. Plastic pipes include plasticized polyvinyl chloride (PVC) pipes.
Steel pipes are comparatively expensive, but they are the strongest and most durable of all water supply pipes. They can withstand high water pressure, come in convenient lengths than most other pipes and thus incur lower installation/transportation costs. They can be easily welded.
Galvanised steel or iron pipes
Galvanized steel or iron is the traditional piping material in the plumbing industry for conveyance of water and wastewater. Although still used throughout the world, its popularity is declining. The use of galvanized steel or iron as a conveyer for drinking water is problematic where water flow is slow or static for periods of time because it causes rust from internal corrosion. Galvanized steel or iron piping may also give an unpalatable taste and smell to the water conveyed under corrosive conditions.
Cast iron pipes
Cast iron pipes are quite stable and well suited for high water pressure. However, cast iron pipes are heavy, which makes them unsuitable for inaccessible places due to transportation problems. In addition, due to their weight they generally come in short lengths increasing the costs for layout and jointing.
Concrete cement and asbestos cement pipes
Concrete cement pipes are expensive but non-corrosive by nature. Their advantage is that they are extremely strong and durable. However, being bulky and heavy, they are harder and more costly to handle. Install and transport.
Plasticized Polyvinyle Chloride (PVC) pipes
PVC pipes are non-corrosive, extremely light and thus easy to handle and transport. Still, they are strong and come in long lengths that lower installation and transportation costs. However, they are prone to physical damage if exposed overground and become brittle when exposedto ultraviolet light. In addition to problems associated with the expansion and contraction of PVC, the material will soften and deform if exposed to temperatures over 65 oC
Installation costs make up a major part of the total cost of a project. Differences in the cost of the actual pipe do not change the total cost of the project much. However the following factors should be considered concerning installation cost and the choice of pipes.
- Weight of the pipe. A pipe that is lightweight can be handled easier and faster.
- Ease of assembling. Push-on joints can be assembled much faster than bolted joints.
- Pipe strength. If one type of pipe requires special bedding to withstand external pressures while another pipe does not, the choice can impact installation costs significantly.
Most importantly, buy quality fittings from a reputable supplier that has the technical back up required for the relevant Products; this is according to Wayne Masters the Product and Projects Manager at Astore Keymak in South Africa. “In our experience it is best to use quality products that carry backup from the suppliers and come with certification,” he adds.
How plastic pipes outperform metal pipes
According to Jamil Ali. A senior Export manager at Muna Noor, plastic pipes are preferred when laying down water distribution networks. He attributes this to the following reasons:
- Corrosion resistant— A plastic plumbing system pipe isn’t easily corroded by exposure to water and common household chemicals. Plastic formulas can be adjusted to allow them to stand up to the demands of various residential plumbing needs, including water supply and drainage.
- Low heat conductivity— Unlike metal, plastic doesn’t conduct heat well so it’s better able to maintain the temperature of the water it carries. While copper pipes require insulation to prevent sweating and dripping, PVC pipes stay dry even with no insulation. That’s especially helpful with condensate drains for air conditioners, boilers and other appliances.
- Non-reactive— Connecting dissimilar metals, such as copper and iron, can cause corrosion. Plastic pipes can be connected with each other or with metal pipes without the risk of damaging chemical reactions.
- Easier installation— Because plastic pipes are light and easy to handle, plumbing jobs done with these pipes nearly always cost less than those that involve metal pipes.
- Fewer blockages— Some plumbers find plastic drainpipes are less likely to clog than metal ones and are easier to unclog when they do.
Jamil says during the past 5 years, the use of plastics in Africa has grown by 150%, with Imports into the continent growing at between 25% and 50%. He however says despite the encouraging statistics, there are challenges facing the Plastic industry in Africa:
- Relaying in conventional production methods, product quality tests, scale of production, and product ranges.
- The conservative attitude of decision makers towards new material like Polypropylene.
- Poor government support and the strong position of the metals industry, and a shortage of good infrastructure to boost the industry.
A leaking distribution system increases the likelihood of safe water leaving the source or treatment facility becoming contaminated before reaching the consumer. Moreover, leaking can result in considerable water loss on the way to the end-user. The distribution system must be designed, managed and maintained to guarantee minimal level of leakage. The internal pipe pressure constantly must be greater than the external hydrostatic pressure. This wil ensure ensure the delivery of the water reducing loss from leaks and minimizing excess growth of pathogenic microorganisms.
A certain level of free residual chlorine will reduce the risks of recontamination within the distribution system. Inflows of contaminated water during distribution are major sources of waterborne pathogens and thus cause of waterborne diseases.
Water pipes are often made of copper and bath fixtures may be made from alloys containing copper. The principal source of copper in drinking water results from leaching of copper from pipes and bath fixtures due to corrosive water. The blue-green stain left in some bath fixtures is a sign of the presence of copper in water. Usually, excess copper in drinking water comes from the leaching of the plumbing system into the water that has been sitting in the pipes for several hours. Therefore letting the water run for 30 to 60 seconds before using it for drinking or cooking will often significantly reduce copper levels.
Sarth Jain, Chairman, Vinyl Pipes Pvt Ltd, advises clients’ to switch to uPVC pipes but with caution. He counsels customers to source pipes with the right quality certifications. Given the n number of manufacturers in the market, many use poor material resulting in Pipes, with a short lifespan. He further shared that at Vinyl, to prevent pipes from losing form in extreme temperatures, their R&D team has developed a proprietary annealing process that strengths the Pipes. All Vinyl uPVC pipes are put through this process. Furthermore, being recyclable Vinyl uPVC pipes carry value even at the end of their lifecycle, bringing more value to the end customer. Vinyl Pipes Pvt Ltd is an Indian based company that supplies complete quality borehole solutions that promise a reliable leak-free installation. The company also supplies uPVC casing pipes as well as Pieziometric Pipes to Africa.
According to Michelle Momberg from Fiberpipe, one of the biggest challenge for most of the local manufacturers in Africa is competition from imported products. She adds that for the case of South Africa, companies are required to comply with BBBEE codes and SABS/SANS quality standards, a requirement that many importers forgo. She says that lack of engineers and technicians is another challenge that affects many countries in Africa, a problem she blames largely on the decision makers.