detention time detention time drogones12 (Civil/Environmental) (OP) 23 May 17 17:43 How to calculate the time that will take a drop of raw water becoming a finished water in a conventional water treatment plant? Is there a formula for it? All input will be appreciated. RE: detention time MartinLe (Civil/Environmental) 24 May 17 06:51 Mean detention time is water Volume in the plant devided by flowrate. Flowrate will vary significantly over time depending on time of day, weather, etc. Volumne would be the volume of all tanks, channels etc. that take part in treatment. Things get more complicated when you consider that part of the water leaves the plant not as cleaned wastewater but as part of the sludge. OTOH, you could ignore the volume of the channels etc. and just add up the detention times the different processes where designed for - this will be plant dependent. RE: detention time bimr (Civil/Environmental) 24 May 17 13:40 There is no such thing as conventional treatment. The retention time will vary from as little as 15 minutes for chlorination only to as long as 2-3 hours for a complicated treatment. Storage times will be much longer.