Im having trouble with this flow map?

okay so i need help im not sure how to make this into a flow map okay i need to turn this paper on the steps of how water treament plants clean the water so its safe for us and everything so like if the first one was " surface water is pumped from the river to the resovoir, then on to the treatment plant" how would that be converted to a flow map by the way a flow map is a map that have big boxes going from side to side and these big boxes have the main ideas and then under each box is two small boxes on details for that main idea...... can anyone help me with an example please???