Water Reclamation and Reuse

‘Wastewater reclamation’ is the treatment or processing of wastewater to make it reusable, while ‘wastewater reuse’ is using wastewater in a variety of beneficial ways. In addition, ‘reclamation’ or ‘reuse’ of water frequently implies the existence of a pipe or other water conveyance facilities for delivering the reclaimed water.

Wastewater Reuse and reclamation:

• Water reuse: Water reuse involves taking what was once wastewater, treating and disinfecting it, then using the resulting high-quality reclaimed water for a beneficial use, such as irrigation for golf courses, parks, highway medians, playgrounds and residential properties. The degree of treatment depends on what purpose the water will serve. Irrigation is the most common type of reuse.
• Water reclamation: Reclaimed water is wastewater that has been thoroughly treated to remove harmful organisms and substances, such as bacteria, viruses and heavy metals, so it can be reused. By using reclaimed water, communities can conserve traditional freshwater supplies and provide an environmentally responsible alternative to disposal of wastewater. Reclaimed water can be safely used for a wide variety of purposes, including landscape irrigation for golf courses, parks, highway medians, playgrounds and residential properties. Reclaimed water also is used for agricultural irrigation; decorative ponds and fountains; groundwater recharge; industrial uses such as cooling; fire protection; and wetlands creation, restoration and enhancement.
• Water recycling: Recycling generally means reuse of wastewater back in the same cycle where it is generated.

Is reclaimed water safe to drink?

The water is clear, odorless and safe, but usable for only nondrinking or non-potable water purposes.

Reclaimed water is permitted for many non-potable uses, including landscape and commercial agricultural irrigation, groundwater recharge; industrial uses such as cooling, process or wash waters; fire protection; wetlands creation; restoration and enhancement.

Reclaimed water is used in commercial agricultural operations including irrigation of edible food crops such as citrus, corn and soybeans. The use of reclaimed water for raising edible crops by the general public is not permitted. It is necessary to provide public education on appropriate uses of reclaimed water. Water users must understand that reclaimed water cannot be connected to potable water plumbing systems and should not be consumed. Reclaimed water service providers also need to monitor their systems to ensure that there is no cross connection with their potable water systems.

Municipal Reuse

Many cities have integrated reuse plans into their water management strategies. In addition to sending reclaimed waters to farms for irrigation purposes, cities themselves reuse wastewater to irrigate parks, playgrounds, greenbelts, cemeteries, and golf courses, and for other non-potable uses such as toilet flushing, fire protection, street cleaning, and fountains.

Water is used in many industrial processes, for cooling, washing, and incorporation into products. Industry accounts for almost a quarter of worldwide water use, and this figure will increase as economic development advances. In the more advanced economies, industry accounts for between 50 and 80 percent of total water demand. Most of this water is used for activities that heat or pollute water, but that do not consume it the way irrigation does. Thus, much potential exists for recycling and reusing industrial water. More than 40 percent of reclaimed water in Japan goes to meet industrial water use needs. In California, only 6 percent is applied to industrial uses.

Direct Potable Reuse

In direct potable reuse, the liquid waste or sewage of a wastewater treatment plant is sent directly into the intake of a drinking-water treatment and distribution plant. Although this process involves the most technologically advanced water treatment processes, and the water that enters the distribution system must meet drinking-water standards, it is the one most argued against by community citizen groups, calling it “toilet-to-tap”. It is presently used only in water-critical situations, such as those that frequently occur in drought areas.

Indirect Potable Reuse and Non-potable Reuse

Indirect potable reuse is the addition to a water supply of reclaimed water derived from pre-treated municipal wastewater. This often is done through the medium of an existing stream or river and, as a result, the wastewater generally is diluted significantly. Many communities use this method inadvertently because their drinking-water intake lies downstream of the collective discharges of other municipalities’ wastewater plants. Indirect potable reuse also is called non-potable reuse because the technologies used for each are the same.