The concentration is calculated on the volume of water that is in the well. The concentration must be at least 200 milligrams of chlorine per litre of water present in the well and must be left in the well for at least 12 hours to ensure any bacteria present are.
idles; idled; idling. Learner's definition of IDLE. 1. of an engine or vehicle: to run without being connected for doing useful work. [no object]. She left the engine idling for a few seconds before she turned it off. The cars idled in traffic.
1. countable noun. The engine of a car or other vehicle is the part that produces the power which makes the vehicle move. He got into the driving seat and started the engine. ...an engine failure that forced a jetliner to crash-land in a field. Synonyms: machine, motor, mechanism, generator More Synonyms of engine.