Nodal Base Demand in Drinking Water Supply Network

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Dear members of The Water Network,

I am a Municipal Engineer working in Bangladesh. We are in process of optimising our water supply network.

I want to identify the leakage of pipe in water supply network.

Please explain: 

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6 Answers

  1. Nodal base demand can be determined by referring to “International Plumbing Code”. You will find various estimate of water consumption such as by bathtub, lavatory, shower head, etc. As mentioned before by some colleague in this thread, you can later use network model such as EPANET or Bentley to simulate your network and optimize production output.

    Meanwhile for leakage in pipes you can start comparing your daily production and total consumption between specific time frame. More complex method you can use District Metering Area (DMA) concept where you can calculate losses on each zone of service. Further step you will need step test method and track pipe using portable leak detector after you found specific area where lekage may occur.

  2. Nodal base demand can be estimated from lots contributing to that node. This can be verified by flow meter measurements over 24 hours during week ends and week days. A pattern can be generated for the 24 hours during week end and week days. The pattern and the average demand can be fed into the US EPANET. Bulk decay coefficient can be estimated by measuring residual chlorine at two outlets such as Hydrants. Leakage in a pipe can be modelled as orifice.

  3. You could collect and log demands at each nodes and feed to the cloud or web based on your IT infrastructure. Analysis of the networks can then be structured and utilized based on the end goals. You need a good physical representation of nodes water distribution network to get good results.

  4. I did not see an amount listed. As you know arsenic is an essential nutrient.  Responsible for all animal fertility, helps build strong bones in new born babies, very essential for the cardio system, help maintain normal mitochondrial cell membrane function in heart muscle cells.  The health range has been determined to be 12 to 50 mcgs.   Using the Archaea species will lock up any excessive amounts of this nutritional element.  This ancient process has been successful in tying up excessive salts (brine) at drilling site and natural desert brine areas.   Arsenic falls into the category of ice cream.  One ice cream cone in one hour is a desert. One ton of ice cream is a toxin to you.  Chemicals not really needed.  But it does keep people employed.

  5. Please allow an observation, and question, regarding water supply in Bangladesh, in general. My understanding has been that drinking water in Dhaka, for example, comes from the aquifer, and that this tends to be arsenic contaminated. Consequently, people get arsenic poisoning. As a result of this situation, I wonder at an alternative possibility that river water (from the Brahmaputra?) could be treated for pathogen reduction. We here, may be able to provide for this on a community by community, point-of-use basis.

  6. In my experience, in each node will be several base demands, each with it own demand pattern. In example, in each building can be same enterprieses, offices and inhabitants. Each category of previously mentioned consumer types have their own demand pattern. I do not think that it will be possible to measure the nodal base demand. At least in our city (Latvia, Riga) each building pay for consumed total water to city waterworks (where I am working) according water meter reading for whole house and data about demand is not divided between consumers. I in my model I take into account SCADA average data about total water delivered in each hour to city network and data about total average day sold water. From there I get average figure of leakage in day. In our city, we have around 20000 buildings. We have data about total average day sold water for each building. They are divided as inhabitants consumers, enterprise consumers and waterworks own consumption. Afterword I according available data about each enterprise character (office, school, supermarket) I developed around 30 different demand patterns. Therefore, in general I did not measure directly nodal base demand, but calculated it from available measurements (SCADA about delivered water and sold water to consumers).

    When I worked in Qatar, for approximate checking of remaining chlorine in network I used recommended in Qatar value for bulk reaction rate -0.7 mg/L 1/day for chlorine. It depends from temperature, and I assume that in Qatar and Bangladesh they could be similar for approximate calculations. Afterwards in same project for Qatar Petroleum we changed disinfectant from Chlorine to Chloride dioxide. Our chemical specialist suggested to use for Chlorine dioxide in Qatar in wintertime bulk reaction rate -1.8 mg/L 1/day and first order wall reaction rate -0.08 m/day