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Peak Hour Water Demand

I'm a 2nd year engineering student doing a group project on building a well in Niger, I need to find what the peak hour water demand is, is there an equation I can use that will do this?

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## 2 Answers

The WHO published the seminal book on water and sanitation in the 1970s https://www.who.int/water_sanitation_health/dwq/monograph42.pdf Warford and Saunders of the World Bank also produced Village Water Supply a few years later. You gotta get both. The WHO book discussed a graphical way to calculate the size of a distribution tank on pages 195 - 201. Good luck. Lemme know if I can help. We've built hundreds of them...

## Comments

Thanks Bruce, I'll check them out now :) Where have you been building wells?

If V is the volume of the average container size (25L jerry can?), and q is the flow rate from your outlet then t=v/q is the time taken to fill a container. The number of containers that can be filled in one hour (N) from a single outlet is then N=60/t. In the absence of data on abstraction you will have to make some assumptions on which times water mot people will collect water. I would go with something along the lines that most households will collect water in the morning, say from dawn to 8:00, or in the evenings from 3:00 until dusk. If you multiply the total number of households by the design daily water demand per household you get the total volume that needs to be supplied during your peak collection times. Divide this by your assumed collection times to figure out your peak water demand. Use a factor of safety of 20-25% due to the sweeping nature of your assumptions. I assume that because this is a class exercise your tutours will be more interested in the logic applied in deriving the figure rather than it's actual accuracy. You could check on-line form your Water Ministry, I would be very surprised if abstraction patterns from village supplies are not available.

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Thanks John, it was one of those things that I couldn't quite get my head around. One of my tutors lent me his RedR book Engineers in Emergencies which has some great advice, think I might put it on my Christmas list :)

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**Nov 16 '17**

If V is the volume of the average container size (25L jerry can?), and q is the flow rate from your outlet then t=v/q is the time taken to fill a container. The number of containers that can be filled in one hour (N) from a single outlet is then N=60/t. In the absence of data on abstraction you will have to make some assumptions on which times water mot people will collect water. I would go with something along the lines that most households will collect water in the morning, say from dawn to 8:00, or in the evenings from 3:00 until dusk. If you multiply the total number of households by the design daily water demand per household you get the total volume that needs to be supplied during your peak collection times. Divide this by your assumed collection times to figure ...(more)