Either way. Cheaper per liter still.
SevenTrent are charging us "£2.41" per 1000L of water. I was paying £2.29 at ECP so even with the 20-30L I had to flush through the system to prep it I am less than a quarter the price already (excluding the system setup and running costs).
In our location if you are on a meter we are charged per cubic Mtr for water from the meter and then get a bill for the same amount for putting in down the drain.