[pct-l] How much water would you bring for a 20 mile day?

[Jon Danniken]

Assume a 20 mile day in the Cascades in mid August, temps between 60F and
80F, mostly in direct sun, hiker acclimated to the temps and activity level,
with  elevation gain over the course totalling 1000 feet (this in the last
eight miles).

Would you consider six liters to be a reasonable ballpark amount to bring,
assuming a water source that night at the end of the journey?  Too much/too
little?

Thanks,

Jon