According to the surfaces water (Hall, 1987), is ‘soft’ and subterranean waters are found ‘hard’ depends on strata of earth comes contact with. There are two hardness of water that are temporary and permanent. Temporary hardness is when the water passes through strata containing a certain of amount salts (magnesium or carbonate of calcium) and will be taken into water which contains the amount of carbon dioxide present. However, for the permanent hardness is when the water passes through strata containing calcium sulphate, magnesium chloride or calcium chloride, it will dissolve without the carbon dioxide in water. For soft water are readily lathers and it is not suitable for drinking uses as it contains some hardness degree in the solution which can cause corrosion of zinc, iron, steel and even lead and copper. Based on Fig. 1.2 shows the process of base exchange for temporary and permanent hardness. This process will remove all the hardness from temporary and permanent of water efficiently by going through a steel cylinder containing zeolites (Hall, 1987).Sodium Zeolite + Calcium Sulphate/Carbonate = Calcium Zeolite + Sodium Sulphate/Carbonate
Calcium Zeolite + Sodium Chloride = Sodium Zeolite + Calcium Chloride
Fig. 1.2 Base exchange process
2. Cold water system
When designing a cold water system for a certain residential building, it is important to know the requirement of Water Authority for local based on Table 1.1 and Table 1.2 by previous work (Hall, 1987). There are two types of distinct systems which are direct and indirect system and some of them are allow to be modified the systems based on Water Authority given. However, in terms of cost saving issues direct system are used in designing this cold water system.
Provision of cold water to cover 24-hour interruption of supply C.P Water Supply
Types of building
Storage in liters
Dwelling houses and flats (per resident)
Hostels (per resident)
Hotels (per resident)
Offices without canteens (per head)
Offices with canteens (per head)
Restaurants (per head/per meal)
Day schools (per head)
Boarding school (per head)
Nurses’ homes and medical quarters (per resident)
Volumes of water, hot and cold, added together required for single use of appliances
Volume required in liters
hand and face wash
3. Direct system
This system frequently used in northern districts, where they can provide an efficient main supply by the large high-level reservoirs. For all sanitary fitting in the system are provided from cold water through directly by the main based on Fig. 1.3 (Hall, 1987) and a cold water feed cistern need only to consume from the hot water storage cylinder. The main supply are usually supplies a cold water for showers, baths, basins for example and it required to double the capacity in liters for the uses of hot water cylinder in the direct system. The capacity in liters of hot water cylinder required more than the capacity in liters for cistern used. Based on Water Regulations, the cistern required 114 liters (minimum) capacity and it also enough for accommodated in the pipework and sanitary systems shown in Fig. 1.4 (Hall, 1987).
Fig. 1.3 Connection to water main
Fig. 1.4 Detail of cold water cistern
4. Back siphonageBack siphonage occurs when the presence of negative or reduced of pressure (vacuum or partial vacuum) in water which mainly located in the drinking water main supply. This is usually created in the pipe connected to a valve or tap, with submerged the outlet into water and also can cause contaminated. This thing may be happening when the water main supply is adequate to snag the water and evacuate a partial vacuum. To prevent the back siphonage occurs, the following statement or points must be perceived. For example, the taps outlets must be connected to baths, sinks and the basins should be above from level of flooding for the fitting, all fitting that have water inlet with low-level version such as bidets must be supplied by from a cold water storage and not from the main supply and in the overflow pipe, the ball valves in water storage cisterns must be situated above the pipe and same goes for the outlets of silencer pipe which must be situated above position of valve (Hall, 1987).
5. Distribution of water for cold water supply and hot water supply
There are five type of pipe which are commonly used in small low-rise residential building for direct system such as communication pipe, supply pipe, service pipe, overflow pipe and warning pipe. Communication pipe are the main pipe which supply the water directly from the resources (Severn Trent Water) and pass through the supply pipe with a minimum 15mm of diameter into the residential building. The communication pipe that running from the main water to the boundary of a property can allow a structure to connect with a multiple water supply. The underground service pipework must be laid at a minimum depth of 750 mm to guard against frost and mechanical damage and must be no deeper than 1350 mm so that it is accessible for repair (Fang, 2018). Polythene plastic services pipe are commonly used in underground applications. It is uncommon for the underground pipes to be expose for inspection unless there are presence of leaking or damage have been reported (Noy, 1994). For old building, they usually use lead underground pipes and because of the medium quickly decay it have been forbidden.
The water from supply pipe will flow to the service pipe and distributed directly to the sink, basin, bath, W.C cistern and to the cold water storage tank with a minimum 100 liters capacity of water for direct system. The stop valve installed between the supply pipe and service pipe to stop the flow of water when there are presence of leaking in pipe. However, the service pipe will drain most of the water to a cold water storage tank. The cold water storage tanks must be located in the tanks room or roof spaces according to the regulations requirement and must be covered by dust-proof cover for health and safety. According in previous research (Seeley, 1987), there are many failures occurred when using copper pipes for connecting the galvanized steel tank because there are certain types of water which comes from the hot water system pipes that are capable in dissolving amount of copper particles. When the water comes into the galvanized tank, there will be a certain amount of copper will be deposited with zinc and it will equivalent amount of zinc is dissolved into it. The zinc and copper will produce electrolytic that can cause the ultimate perforation and coating of zinc, then rusting begins to take place and cause the tank to leak slowly. In generally, for a hot water system is best constructed throughout of copper, unless previous experience in the district shows it to be safe to use these materials together based on previous inspection (Seeley, 1987). To prevent the galvanized steel cold water tank from becomes rusting and leaking is by painting the internal surfaces with non-toxic bituminous solution which can give protection coating to the surfaces. Furthermore, using plastics tank and glass fibre can help the tank to last longer. Based on the article, Building Research Establishment (BRE) have found where trussed rafter members have been distorted because the tank bearers were incorrectly sized and positioned, pipe joints disturbed and chipboard tank platforms have become wetted by condensation and collapsed. Moisture damage has also been caused by overflow pipes having too small bore, sagging or having inadequate slope (Seeley: 1987).
The water from cold water storage tank will flow through the distribution pipe into hot water cylinder. During supplying the hot water in this direct heating systems, there are few components in the system that are cold water supply pipe, boiler, hot water cylinder, expansion pipe, the flow and return pipes. The gas-fired boilers are used in this system as it usually can be mounted on wall and connected to a conventional or balanced flue. Sometimes, there are two types of difference device to operates the boilers which are the automatic electric ignition and a permanent pilot light. The boilers are usually installed in a kitchen area depends on the layout in a domestic property. If is not permitted, the boilers can be installed in a specific cupboard and provides a ventilation for the compartment. The two air vents must be provided and both can be either through directly outside air or a room that can be ventilated located at low level and at high level. The full way gate valve are attaches to distribution pipe in order to control the fluids in low-pressure systems and have less resistance of fluids flow than the globe valve (Hall, 1987). The distribution pipe is a pipe within the structure that convey water from the water services that connected to a cold water storage tank to the point of utilization. The flow pipe must be located at higher position at water tank because if the ball valve were damage or broken, this pipe will help the water to flow to the other pipe. It will need to be mounted slightly above the full water tank that supplying water to overflow in the event of damage to the ball valve and pipe. Based on Fig. 1.5 are the design sketches for water services.
Fig. 1.5 Design of direct system of cold water supply and hot water supply
6. Sanitary fittings in pipework
The sanitary appliance discharge through the stack pipes or the multi-use discharge pipes in single stack plumbing. For this pipe design, the stack for a bath waste must be above at least 200 mm below entry in a WC pipes. The sink waste, baths and basins also required 75 mm deep seal and 50 mm for WC deep seal. Based on Approved Document H1 of the Building Regulations 1985, it requires 3 m maximum pipe length of 40 mm and 4 m pipe length of 50 mm. Within a good functional of WC flushing cistern must be filled water in 2 minutes per once when used and the orifice valve must be exactly have the same supply pressure in flushing cistern to give required flow for water. Wash basins, baths and sinks must be installed without using the overflows passage. The length between the bottom of cold water cistern and shower rose is 900 mm to maintain the water pressure from cold water cistern.
Based on article (Stauffer: 2018), a low-flow toilet is commonly known as a flush toilet which use a special cistern and siphonage design to remove waste and use less of water. This toilet is designed specially to less in water use than a full-flush toilet. Basically, the low-flow toilet required less than 6 or litres of water to remove for urine only and it can operate by using gravity and vaccum. During previous research (Stauffer, 2018), the user needs to use two or more flushes in order to clean the bowl which is precisely they need a large volume of water. For this case, they have decided to modify the passageways in toilet bowl to reduce amount of water use which it can provides a different volume of flush to solid waste and liquid waste contains two button for each uses. For now, they also use and automatic low-flow toilet that can provide
In order to further improve the performance efficiency and economic of industrial center for water service in future, a strategic design approach water use have been constructed in this report. Based on the explanation above, the design have been focusing on how the distribution of cold water supply and hot water supply for small low-rise residential building which are more into total usage of waters by users in property and the quality of water. It is important to control the usage of water as it can minimize the cost to regain water supply. For water quality section, the water have to go through various water treatment. The water must be undergoes a few process such as pre-chlorination, aeration, coagulation, sedimentation, filtration and disinfection. However, for domestic uses, the water will be in softening process (ion exchange) to disinfect and removes large metal ions.
Hall, F. (1987). Building services and equipment. Volume 1. 2nd ed. Harlow, Essex: Longman, pp.1-16.
Noy, E. (1994). Building surveys and reports. 2nd ed. Blackwell Publishing Ltd, pp.227-246.
Seeley, I. (1987). Building maintenance. 2nd ed. Basingstoke: Palgrave, pp.177-180.
Fang, Y. (2018). Domestic Cold Water. Coventry: Dr Yueping Fang, pp.28-30.
Stauffer, B. (2018). Low-flush Toilets | SSWM – Find tools for sustainable sanitation and water management!. online Sswm.info. Available at: https://sswm.info/water-nutrient-cycle/water-use/hardwares/toilet-systems/low-flush-toilets Accessed 2 Nov. 2018.
Architects, Z. (2018). Blog · Ziger/Snead Architects. online Zigersnead.com. Available at: http://www.zigersnead.com/current/blog/post/waterless-urinals-how-do-they-work/12-15-2007/555/ Accessed 3 Nov. 2018.
PIPELINE (2000): Alternative Toilets Options for Conservation and Specific Site Conditions. Morgantown: National Small Flows Clearinghouse Accessed: 8 Nov. 2018