Water age just increase in some nodes during the simulation

Hello everybody,
I’m running a water quality simulation using water age as parameter, the issue is that in some nodes it doesn’t reach a stable condition and the more extended is the simulation time the more the water age just increases. In particular, the low values remain the same, while the peaks of the cycle become higher and higher. I’m using schematic networks, as Anytown, and they all have the same problem.

Does anyone know why and how to fix it?

Best regards,
Claudia

Welcome, @claudiaq - would be helpful if you could post the inp file as a dropbox link or equivalent. That way we could run the system and discuss the particulars. But in general, water age can take quite some time to evolve into a stable range at the extremities of the system - depends on tank retention time, dead-end demands, etc.

The initial “burn-in” can sometimes be reduced by setting a global water age as an initial condition, but some allowance should be made for that initial period of evolution regardless. Ideally should account for the total system retention including effects of tank mixing. In practice, I’ve seen some networks that need several weeks of simulation backfill to reach “stability” in water age predictions.

Welcome @ claudiaq

Please send the inp file, just to see the network behavior closely. Water age some time can be reduced by changing the path between sources or tanks and demand nodes.