Hi Mick, Understand that you ...

Hi Mick, Understand that you are talking about the potable water supply here, however the increase in population would also lead to the increased waste water flows as well. Are you talking about gradual natural increase in population over say 5 -20 years or a seasonal one like in the tourist areas where influx of transient population arrive at certain times every year? In any case - you should look at both storage and treatment as one, rather than separate items. Some treatment design can accommodate 10-25% variance in flow rate, some can not. There is also a min retention time required for the raw water depending on its source, however it also can be (temporarily) reduced with some adjustments to the primary/secondary treatment at your TP. In the worst case scenario - you might need to upgrade some parts of you TP to accomodate the increase in peak flows. That should be balanced with the increase in the storage lagoons volume - the best solution will be determined by the land availability/costs, TP design, operational rational, seasonality, population projections etc. Not much of the answer - I know - bit still my 5 c worth... Regards, Iouri