Water purification turns wastewater into drinking water

The North City Water Reclamation Plant in San Diego, US, may have found a way to make wastewater and sewer water drinkable. A two-year study has been looking into ways to purify wastewater enough so that it can be used as drinking water, meaning less water has to come from natural resources.

The City Council voted to take the purification process forward and work towards turning 15 million gallons of wastewater into drinking water, every day. The idea was previously termed 'toilet to tap' and was not popular with the majority of people living in the city. However with recent results showing just how pure the water becomes, 73 per cent of people living in San Diego are now in support of the process going ahead.

The water that is produced has been proven to be purer than the drinking water the city is currently using. Nine thousand individual tests into the water quality show that it upholds all of the federal and state drinking water standards. Once the water has been treated it contains lower levels of dissolved salts and organic contaminants than water being sourced from aqueducts or the current drinking water.

The process has several different levels, ensuring that the water is entirely safe for consumption once it has gone through the final stage. It begins with microfiltration, which uses plastic tubes that have hollow membranes inside. The microscopic pores on their surfaces filter microbes and other contaminants. The water then goes through the process of reverse-osmosis. This is the high pressure filtering designed to remove salts and other solid matter. About 80 per cent of water ends up becoming filtered.

If plans are to be approved a purification plant and pipeline is set to be built. It is estimated that the building work will cost around $369 million (£240 million). The pipelines will transport purified water.