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Age analysis - Tank empty

Dear All,

I attached my water model for reference. the issue is, i am not getting correct result for age analysis "Age (maximum) (hours)"

In the model you can see "ADD + 10% for Age with reservoir" and "ADD + 10% for Age with tank and reservoir" as two scenarios for age analysis. Basically, the difference between scenario is water source as one scenario analysis with directly from reservoir and other with tanks.

I showed the results to client with "ADD + 10% for Age with reservoir". Since, there is no notifications in it. Further, u can see other scenarios apart from these scenarios. All those are worked with tank as water source. You can see the change in the active topology. these scenarios are working well.

Now, the problem is client needs the age analysis with tanks as water source as actual existing. So i tried, but notification shows all tanks are empty. (Note: all the tank details are actual as built). hence i inserted a reservoir for permanent source of water. After, introducing the tank, the notification says some times, tanks full or empty. since, i was not able to fix the elevation of reservoir.

Hence, how to fix this age issue with tanks. Further, I attached 2 squilte files one "Islandwide prposed 150mm and Without FF at existing SB area.wtg" is the one all iterations i done. other one "Original shown to client" is the one i shown to the client. the main difference we can see is the pumping station header main. I faced problem with the original for age in commmon discharge pipes with out flow. so i connected all the discharge pipes at one point.

expecting the Solution.


  • Hey Dan,

    These three tanks are constructed for 1 day storage volume. If any maintenance works carried out in the transmission main, these tanks will take care of supply. Further, age analysis will be dependent on the distribution system. Since, what ever the fluctuation in the tank, pumps are going to pump the  same  flow. There is no fluctuations in the pumps. In the analysis all the demands are fixed.  Supply to the distribution system is not intermittent. it is continuous supply. Problem wat i am facing here is how to provide a proper continuous supply to tank . I was not able to solve the age analysis with tanks. If there is any option let us know.



  • Hello RSP,

    Take a look at the following Wiki articles. The first is about Modeling Fixed Inflow from a Marginal source. This may help you figure out how to model the continuous supply to the tanks. There are a couple of very good options.

    Modeling Fixed Inflow from a Marginal Source

    Concerning Tanks, If two tanks are close to one another (e.g. on the same lot connected by a large pipe)

    Water in the model can essentially "slosh" between them even though this does not occur in the real system. It is best to represent two tanks as a single tank with the same effective area.

    Please let me know if you have any questions or comments.