We talked about water recycling quite recently, but it’s in the news again as California continues down the dangerous road towards severe water shortages. A succession of dry years means the state’s traditional water reserves are running low, and unless there’s a long stretch of wet weather (and plenty of winter snow) water rationing is almost inevitable across huge areas. Government figures now show that all of California is in drought conditions, while 80 percent is experiencing a severe drought and over half “exceptional”. Analysis of tree ring data suggests it’s the driest period n at least 1,200 years.
As well as being bad news for the state’s residents the situation is also potentially disastrous for the vital agriculture industry. Because of the dry climate California farmers rely heavily on irrigation for most crops and a drought leads to restrictions on what they can grow; if it continues long enough many could be forced out of business altogether, and there may even be irreparable damage to the land itself. Meanwhile cities need water for homes and businesses as well as essential public services, like the fire department. That makes it essential to use water as efficiently as possible and recycling has to play a major role there.
Water recycling is something that needs to be done at all levels, from the state through utility companies down to individuals. California is one of the world’s leading recyclers, with over 250 waste water processing plants currently operating – and that number’s set to grow. Currently up to 580,000 acre-feet of waste water is recycled every year, three times the amount processed in 1970, and by 2030 it’s likely to have quadrupled again. The main use of waste water is for irrigation; it’s much easier to treat it to this standard than to make it fit for drinking, while using it reduces the demand on natural water resources like reservoirs and aquifers.
Of course consumer demand puts pressure on resources to, but new recycling technology means it’s now much easier to make potable water from waste. Orange County’s Groundwater Replenishment System uses microfilters, reverse osmosis and UV disinfection to purify conventionally treated drainage water, which is then pumped into pools to refill the Santa Ana aquifers. This program treats 70 million gallons a day – enough to supply half a million people.
Recycled water can also be used in industry. Many industries use huge amounts of water; often it’s contaminated and needs treatment before it can be discharged, and other times it needs to be pure water. There are many other uses though, such as coolant. Cooling water doesn’t need to be potable and isn’t heavily contaminated in the process, so waste water that’s had a standard treatment can be easily used. Again this reduces demand on fresh sources.
While recycling will stretch water supplies as far as possible it can’t fully compensate for a lack of rainfall, so as long as droughts are a possibility it’s also vital that we look for ways to reduce consumption. One controversial issue is the cultivation of rice in California. Rice needs huge amounts of irrigation and many people say it’s not a suitable crop for a dry area; local food advocates disagree. This is just one of many issues that needs to be solved if we’re going to preserve our water supplies for the future.