Dangerous goods: Any solid, liquid or gas that can harm people, other living things or the environment.
Detention time: The calculated time required for a small amount of water to pass through a tank or pipe at a given flow rate or the actual time a small amount of water stays in a tank or basin or a reservoir.
Design parameters: Key performance
levels associated with a process establishing high, low and normal
operating levels. These are set when the process is designed and establish
normal operating levels (eg. Max, min flow rates).
Diarrhoeal: Substances that can produce a diarrhoea, usually by ingesting certain pathogens spread through water.
Diffuse source pollution: Pollution that comes from a wide range of points, usually widely dispersed.
Diffusers: Devices that assist in spreading substances out widely, used to spread out and slow down influent water as it enters from a pipe to a wide basin.
Diffusion plates: Plates, usually porous, that aid in diffusion.
Disinfectant: Antimicrobial substances applied to non-living objects to destroy micro-organisms.
Disinfection (DIS-in-FECK-shun): The process of using a disinfectant to destroy micro-organisms.
Disinfection by-product: A by-product formed when disinfection is carried out.
Dissolved organic carbon: Very fine organic particles that are dissolved into water causing colour. Organic molecules that are small enough to be dissolved in water, which can alter the colour of the water.
Distribution system: A system to
distribute water which may include valves, pumps, pipes, storage tanks,
meters, etc.
Distribution: The movement of water from one part to another part of the water treatment process and then to customers.