Water Demand Calculations

I've had numerous questions about water demand calculations. I provided this information to two of the ENE students. I'm sharing this to all now.  I wish I had more precise values, but I've checked with an engineer who has been in the field for many years and he thought this is reasonable.

I've been trying to wrap my head around this too as we've been given so little information.  I would say that if there are 50 trucks in use, then you likely have 100 employees (2 people on a truck) out in the community at any one time.  I'd assume they arrive, put on their uniforms, perhaps use the restroom, and head out on the road.  Come back at lunch time to eat in the lunchroom, then leave and return at the end of the day, change out of their uniforms, perhaps use the restroom, head home. If this is the case then you would likely have a peak usage of water in a short time (you could make an assumption of number of flushes, if you wanted to go down to that level).

Let's say that each truck is in the "shop" for repairs one week per year. That means that at any one time there are perhaps 2 vehicles in the shop for repairs. (This doesn't include vehicle washing).  Perhaps there are 10 mechanics onsite for repairs.

Let's say every truck is washed twice per week. That means that we have 140 washes over 5 days, perhaps 6 hrs/day.  So about 3 washes at one time. Three people per wash = 9 people. Round to 10.

I'd assume the remaining people are working in the office.

Typically peak hourly demand is 5.3 x the average daily demand (as per the Davis book).  You could also make some assumptions, i.e., that X% of the office workers work 8-5 pm so the usage is based on the building being essentially empty for 2/3 of the day. 

2.2 x average daily demand = max daily demand.