What Water is Right for What Use?


by Doug Pushard

Water in the Desert: Abiquiu Lake, New Mexico

 

Water, water everywhere but what is right for me?  With water we do have lots of choice and not all are created equal. You are probably wondering what I am talking about.  What choices, what water?

Of course there is city water that most of us utilize abundantly.  But we also have rainwater, greywater,  and blackwater.  All of these are potential sources of water that could be used to drive our net water use to zero or better; help us to become a net producer of water.

Each one of these waters has different characteristics that make it well suited for a primary, secondary and tertiary use. Each type of water has different upfront costs and varies on impact of net water use. For example, city water has chlorine added to it to help keep it disinfected on route to our homes from the distribution plant.  This same chemical may create healthy water for us, but over the long-term is not healthy for plants.  It creates salt build-up in the soil that rainwater and fertilizers help offset. 

So city water is a good primary source of potable water, but should be secondary or tertiary when it comes to landscape water use.  Below is a summary of the characteristics of each source of water.
 

  City Water Rainwater Greywater Blackwater
Drinking Water Quality X      
Nutrient Rich     X X
Bacteria   X X X
Chlorine X   X X
Mineral/Salts X   X X
pH¹ 6.5 – 8.5 5.6 – 6.0 5.3 to 10.8 6.5 – 8.5
Pharmaceuticals X   X X

Of course, the advantage of city water is that is plumbed to almost every house and it is cheap.  The disadvantage is that is not great for all uses.  Looking at the sources of water without considering costs would result in a much different water use pattern. For example, if all homes were plumbed for water storage and had water filtration systems, we would use the best water for the right use to minimize or eliminate our water footprint.

CURRENT WATER USE PATTERN
 
  City Water Rainwater Greywater Blackwater
Drinking Water Primary Waste Water Waste Water Waste Water
Toilet Flushing Primary Waste Water Waste Water Waste Water
Clothes Washing Primary Waste Water Waste Water Waste Water
Landscaping –Subsurface Primary Waste Water Waste Water Waste Water
Landscaping – Above ground Primary Waste Water Waste Water Waste Water

 
Looking at our water use from this perspective then our water use pattern might look something like the following. 
 
  City Water Rainwater Greywater Blackwater
Drinking Water Primary Secondary    
Toilet Flushing Tertiary Primary Secondary  
Clothes Washing Tertiary Primary Secondary  
Landscaping –Subsurface   Tertiary Primary Primary
Landscaping – Above ground   Primary Tertiary Tertiary
Landscaping – Gardens   Primary Tertiary Tertiary
Pools/Water Features Secondary Primary    
 
Blackwater, greywater and rainwater all require some form of onsite treatment to be able to use as depicted in the chart above.  These technologies exist today and are very feasible. 

If implemented in this fashion our water footprint would drop significantly. One local Santa Fe area resident that has mirrored this water use pattern is using just 15 gallons per day per person (GPCD). Compare this to our city wide average of 90 gallons!  This does not require a lifestyle change it only requires a change of how we think about water. All water is precious and life giving, versus tap water is FREE and all other water is waste.

Besides the obvious benefits of saving water and extending our water supplies well into the 22nd century; our plants and soils would be healthier producing more fruit, vegetables, flowers and shade at a much lower water cost than today. Our need to be taxed to secure future water sources and build new filtration plants would be all but eliminated for the foreseeable future.

We have vast amounts of wasted water today.  We must view this water not as waste, but precious and irreplaceable.  With this mind set again we will begin to change our behavior and secure our water security for decades to come.

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