This metric is based on the Global Reporting Initiative (GRI) Standards Guidelines (see details on indicators here). It covers one of the requirements of the indicator under Disclosure 306-1 Water discharge by quality and destination. The full indicator covers the following:
a. Total volume of planned and unplanned water discharges by:
ii. quality of the water, including treatment method;
iii. whether the water was reused by another organization.
b. Standards, methodologies, and assumptions used.
The amount and quality of the water discharged by the organization is directly linked to ecological impact and operational costs. By progressively improving the quality of discharged water or reducing volumes, the organization has the potential to reduce its impact on the surrounding environment. Unmanaged discharge of effluents with a high chemical or nutrient load (principally nitrogen, phosphorous, or potassium) can have a significant impact on receiving waters. This, in turn, can affect the quality of the water supply available to the organization and its relationship with communities and other water users.
Water effluents can be discharged to subsurface waters, surface waters, sewers that lead to rivers, oceans, lakes, wetlands, treatment facilities, and ground water. Discharge of collected rainwater and domestic sewage is not regarded as water discharge.
Biochemical Oxygen Demand (BOD) is a measurement of the amount of dissolved oxygen needed by anaerobic organisms to break down organic material in a water sample at a certain temperature over a certain period of time. This measurement can be used to assess the degree of organic pollution in water discharge and is used as an indicator of water quality. BOD can be reported in tonnes of organic material or in kilograms per tonne of product produced.
This metric is looking for the amount of organic material in tonnes (may be labelled as "Biological Oxygen Demand" or "Biochemical Oxygen Demand") contained in the company's water discharge.
Search the report for the GRI Standard code 306-1 or do a keyword search of 'BOD' or 'oxygen demand' or 'water discharge'. If found, add the BOD value in tonnes and include a comment documenting exactly where within the source you found the information (page number) and include details of simple or complex calculations or conversions made to determine the metric value.
If the BOD value is reported in kilograms per tonne of product produced (kg/t.p.), you will need to convert this value into tonnes. To do so, find the tonnes of product produced in the report (if possible) and multiply the kg/t.p. by this value. Then convert the answer from kilograms into tonnes. Make sure you explain your working in the comments section.
If you cannot find the BOD value in the company's report or cannot convert the value as reported, check the 'Unknown' box, and add any relevant comments before hitting submit.
Companies may use an earlier G4-EN22 code to report this indicator.