We don’t have enough water where we need it. If we don’t learn to deal with drinking toilet water, we’re going to be extremely thirsty. Only 2.5 percent of the water on the Earth is fresh water, and less than 1 percent of that is usable and renewable.
Taking the salt out of ocean water sounds like a good idea, but it’s economically and environmentally far more expensive than toilet water recycling. It also uses more energy and produces more greenhouse gases.
The recycled toilet water sounds dirty. But seawater, like other non-recycled water, is at least as dirty as whatever comes through a toilet-to-tap program. When you know how dirty all this water is before treatment, recycling toilet water doesn’t seem like a bad choice. Hundreds of millions of tons of toilet water enter rivers and oceans.
Water in lakes and rivers used for drinking is cleaned along with rest of our water supply. But no treatment system will ever be 100-percent reliable, and people who worry about pathogens (病原体) in toilet water should worry about all drinking water. Super-treated wastewater is clean enough to drink right after treatment. Recycled water is often of better quality than existing drinking water. And although putting water into the ground, rivers, or lakes provides more filtering (过滤) and opportunities for monitoring quality, the benefits are largely psychological(心理上的).
Unless we discover a new source of clean drinking water, we’ll have to consider projects to make wastewater a reusable resource. The costs for getting a system in place and educating the public may be high, but it would save us the expense, both economic and environmental, of finding another river or lake from which we can get water.
64. What percentage of the water on the earth is fresh, usable and renewable?
A. 2.5 percent. B. 1 percent.
C. 75 percent. D. 0.025 percent.
65. ________ is the source of drinking water most recommended by the writer.
A. Recycled toilet water B. Treatment of seawater
C. Fresh water in rivers and lakes D. Water put into the sea
66. Compared with recycled toilet water, treatment of seawater__________.
A. produces less greenhouse gases B. does less harm to the sea
C. costs much more D. is more friendly to the environment
67. The best title for this passage might be “___________”.
A. It’s Time to Drink Toilet Water B. Water Is Scarce
C. Seawater Treatment D. Rivers, Lakes and the Ocean