Dood! Dave and I were talking about that at dinner last night, a gigantic-ass pipeline. He told me that back during the drought of the 70s the county of Marin had to do that, they went completely dry.
That doesn't make any sense to me. The waste water is considered 'brine.' I mean, maybe it can go back through the RO, but it'd tax the hell out of the membranes.
Disadvantages
Household reverse osmosis units use a lot of water because they have low back pressure. As a result, they recover only 5 to 15% of the water entering the system. The remainder is discharged as waste water. Because waste water carries with it the rejected contaminants, methods to recover this water are not practical for household systems. Wastewater is typically connected to the house drains and will add to the load on the household septic system. An reverse osmosis unit delivering five gallons of treated water per day may discharge between 20 and 90 gallons of waste water per day.
[18]
Large-scale industrial/municipal systems recover typically 75% to 80% of the feed water, or as high as 90%, because they can generate the high pressure needed for higher recovery reverse osmosis filtration. On the other hand, as recovery of wastewater increases in commercial operations, effective contaminant removal rates tend to become reduced, as evidenced by product water
total dissolved solids levels.
Due to its fine membrane construction, reverse osmosis not only removes harmful contaminants present in the water, but it also may strip many of the good, healthy minerals from the water. A number of peer-reviewed studies have looked at the long-term health effects of drinking
demineralized water.
[19] However, demineralized water can be remineralized and this process has been done in instances when processing demineralized water for consumption. An example of this process is
Dasani, which adds sodium chloride (salt) and potassium chloride to its water for "taste", according to the company.
[20]
