Consider it another way.
Wetting, filling and hanging the Millbank bag, 30 seconds.
Placing a pot under the bag when water level drops to the line, 10 seconds.
Hanging the pot over the fire when full, 10 seconds.
Taking the pot off the fire when boiled, 10 seconds.
Although there is a lot more time between these actions the only time it really costs you is the time you are actually
Result? Two litres of water filtered and treated for 1 minute of action, faster than any hand pumped filter I know of.
If you want your water cold simply leave it to cool until the morning.
Another source of water that can sometimes be utilised is rainwater collected from your shelter tarp or fly sheet. This can be used with very little treatment in most places.