Toilet To Tap
In Orange County, California, they are about to turn on a new facility to recycle sewage into potable water. Regulations prohibit the direct reuse of the water, so it will not go directly into the drinking water system. Instead, the treated water will be injected into the ground, feeding aquifers and proving a freshwater barrier to block the infiltration of seawater into the aquifers.
But on Nov. 30, for millions of people here in Orange County, pulling the lever will be the start of a long, intense process to purify the sewage into drinking water — after a hard scrubbing with filters, screens, chemicals and ultraviolet light and the passage of time underground.
On that Friday, the Orange County Water District will turn on what industry experts say is the world’s largest plant devoted to purifying sewer water to increase drinking water supplies. They and others hope it serves as a model for authorities worldwide facing persistent drought, predicted water shortages and projected growth.
The process, called by proponents “indirect potable water reuse” and “toilet to tap” by the wary, is getting a close look in several cities.
The San Diego City Council approved a pilot plan in October to bolster a drinking water reservoir with recycled sewer water. The mayor vetoed the proposal as costly and unlikely to win public acceptance, but the Council will consider overriding it in early December.
Water officials in the San Jose area announced a study of the issue in September, water managers in South Florida approved a plan in November calling for abundant use of recycled wastewater in the coming years in part to help restock drinking water supplies, and planners in Texas are giving it serious consideration.
Here's the website for the so-called "Groundwater Replenishment System." They have animations that show how the process works. I know a lot of places down in Florida use some form of recycled water for landscaping. I don't know if this is going to catch on or not, But when you really think about it, how clean is "natural" water?
By feeblemind, Tuesday, 27 November , 2007 @ 7:45 am
This is probably a good idea. The problem is the ‘ick’ factor.
By martian, Tuesday, 27 November , 2007 @ 9:14 am
They are doing exactly what the natural processes would do - they’re just shortening the time involved. To answer Gaius’ question “how clean is “natural” water?” - the answer is, not very clean at all. “Natural” water contains all kinds of waste products (feces, urine, etc.) from animals, fish and people, pollutants from the surrounding environment, etc. That’s why we spend so much effort to purify and chlorinate “natural” water before we use it in the first place. In fact, recycling human sewage may actually start the process with water that has less pollutants than “natural” water. However, feeblemind is right - there is an “ick” factor involved here because we KNOW exactly where that water is coming from in contrast with “natural” water that we can ignore the origins of because it’s “natural”.
By sam, Tuesday, 27 November , 2007 @ 1:10 pm
It makes sense to inject the treated wastewater into the aquifer rather than just letting it run into the ocean. I assume the “ick factor” is that they are drawing water from the same aquifer to supply the potable water for the area. If the injection site is far enough away from the extraction site, then it shouldn’t be a problem. Sort of like the old rule of not siting an outhouse within a hundred feet of a well or a stream.
By sam, Tuesday, 27 November , 2007 @ 1:17 pm
The website notes that the water would replace water from the Colorado River. Since upstream cities along the Colorado River discharge treated sewage back into it, and agricultural irrigation drainage flows into it as well, the water quality is probably not that good anyway. I’m glad I live in an area where much of the water comes from protected mountain watersheds. Better to be upstream than downstream.