1. The problem statement, all variables and given/known data in order for a well to supply 4.5 million litres of drinking water per day, at a minimum total hardness of 60mg l-1 as Ca, calculate the daily throughput of the reverse osmosis plant assuming that 30% of the feed to the plant comes out as reject. 2. Relevant equations a table provides the following info: total hardness (as mgl-1 CaCO3) at feed is 660 but at permeate it is 4 3. The attempt at a solution i suspect i must break down CaCO3 into its constituents however i cant remember how to do this. Iwould be very grateful for a pointer in the right direction.