This is a question that more and more people are asking as water becomes more scarce and more expensive. The answers are wide and varied in scope depending on specific details such as who is collecting it, where is it being collected and for what purpose.
So, for instance, it may be a city who is looking to collect rainwater to turn it into drinking water, or perhaps a homeowner wanting to minimize his city water bill by collecting and using water for non-drinking purposes.
All across the spectrum, there are companies developing collection/reuse technologies, and there are individuals coming up with their own engineering ideas. The answers to this question are literally limitless. However, here are a few standard thoughts and ideas.
Rainwater or stormwater is it is called when it goes into sewers is typically what we talk about collecting and reusing. For the homeowner downspouts running into 55-gallon drums are the most common method of collecting water. Many have used this for gardening or other non-drinking applications.
The limited size of the collection barrels and the surface area of the home limits just how much water can be collected. So the first option is that a homeowner could perhaps tie all his downspouts into an underground tank of larger capacity and then engineer a treatment system to reuse it, even to the point of making drinking water. Local codes and EPA rules need to be heeded, however.
Next, one could use what is called permeable concrete which allows water to filter through and be collected underneath. Once collected it can be pumped into storage and then into a filtration system. Once again, the surface area limits how much water can be collected. A small driveway is not going to pass very much water. Some communities are putting this permeable concrete everywhere and designing their own water utility based on rainwater and filtration.
At the end of the day, the answer to this question is always the same. It is very, very, extremely expensive to reuse water. he cost of collection, storage, pumps, purification technology and the legal issues such as insurance liability, EPA testing, OSHA and local health codes all come in to play.
In all honesty, there are only two options for the homeowner to reuse water.
- The traditional barrel at the end of the downspout
- For the wealthy who do not care about cost, they can indulge themselves
In general, the cost per gallon of collected/reused/ filtered and redistributed rainwater ranges between $1.00 for the best technology, to as much as $3.50 per gallon for the smaller volumes/less efficient technology.
The national average cost for city drinking water is $1.50 per 1,000 gallons or less than a penny per gallon. Why would anyone want to run their own water recycling plant and pay $3.50 per gallon, when the city charges, six-tenths of a penny per gallon? Plus the cost for a personal recycling plant can easily cost $20,000. Add to that unless it rains the entire system is useless.
So the real question to ask is not what are the most clever, but instead, are any of them economical compared to municipal tap water.