“Annual precipitation is in the region of 400 billion cubic meters, of which 70% or 280 bcm evaporates,” Qasem Taqizadeh Khamesi was quoted as saying by IRNA Sunday.

Due to its geographical proximity, 1% of the country’s area receives 1,000 millimeters of rain and snowfall. This is while annual precipitation in 28% of the land is less than 100 millimeters per year, Financial Tribune quoted him as saying.

Given the limited (fresh) water resources in many countries, people are forced to use the precious resource prudently by adopting a variety of ways, one of which is tapping into unconventional sources like greywater.

This method, however, remains a far cry in Iran.

“Using greywater can help reduce extraction of underground water by up to 40%,” he said, adding that 80% of urban wastewater can be treated and reused.

Greywater is defined as any domestic wastewater produced, excluding sewage. The main difference between greywater and sewage (blackwater) is the organic loading. Sewage has a much larger organic content compared to greywater. Greywater is captured from household sources like sinks, hand-basins, showers, etc.

With proper treatment, greywater can be put to good use, ranging from toilet flushing to farming. Treated greywater can be used to irrigate both food and non-food production units. Nutrients in greywater (phosphorus and nitrogen) are an excellent food source for plants.

Khamesi argues against the use of high quality and costly potable water for purposes that do not require such water, like irrigation. 

“Reusing greywater helps curb demand for expensive-to-treat potable water.”

It costs the government 25,000 rials (19 cents) to produce one cubic meter of water,  whereas consumers pay 40% of the total cost (10,000 rilas or 7 cents), which partly explains why the rapidly dwindling resource is taken for granted.

Referring to the experience of other countries, the Abfa official said  Japan treats at least 345,000 cubic meters of greywater a year, of which 230,000 cubic meters is used for urban green spaces.

The reuse of greywater is being increasingly practiced in many countries, namely the US, Australia, Cyprus, the UK, Germany and Jordan.

Located in one of the world's most water-stressed regions, Iran suffers from low rainfall and excessive consumption plus high levels of water loss because of aging infrastructure and outdated and prohibitive farming practices.