Catching up to the 21st century, part 10...soft water

February, 2007

My well water is very hard. I would prefer to use well water only for fire suppression (sprinklers) and irrigation. I would prefer all fixtures in the home to be supplied with low or medium hardness water. I do not want to use a conventional water softener because salt (or potassium) is added to:

1. the water as a result of normal use
2. the environment as a result of filter regeneration

What is an unconventional water softener, you ask? Mother nature will drop about 23,000 gallons of rain on my rooftop during an average year. A rainwater harvesting system has the potential to store about 18,000 gallons of this free, soft water. The stored water can either be kept separate and treated for domestic use. Or, it can be mixed with well water, treated for domestic use and supply fire sprinklers. Mixing the water is a little simpler than having separate storage systems for sprinkler and domestic use. Mixing soft rainwater with very hard well water will result in a hardness somewhere between the two extremes. The primary green features of rainwater harvesting are:

• free water softening - without using salt or potassium
• reduced fixture maintenance from hard water scale when mixing treated rain water with well water for domestic use
• preserving groundwater supply by reducing well usage
  

Catching up to the 21st century, part 9...Pyrolox well water filter

January, 2007

Our well water has a barely acceptable level of Iron (Fe) and a barely unacceptable level of manganese (Mn). Capitola Pump, the well installer on our land, recommended an ozonator from Triple O to treat the well water. Ozonators reduce Fe, Mn, hydrogen sulfide (H2S - rotten egg smell) and kill bacteria too. The Triple O is set up with a recirculation pump to continuously filter water in the storage tank resulting in drinking quality water. I heard from people I trust that these units perform well. However, I was concerned with periodic filter and bulb maintenance and continuous electricity use. In a green home design, I think all purchases should strive to reduce initial material use as well as ongoing maintenance and power usage. I decided to use the ozonator as my baseline and try to find a greener solution for my specific application.

A little research on well water treatment comes up with Pyrolox iron filters. These filters reduce Fe, Mn and H2S by catalyzing a reaction which causes the contaminants to precipitate out of the water as Fe, Mn and H2S oxides. Periodic backwashing with water removes the oxides from the filter and rejuvenates the Pyrolox filter media. How often to backwash depends on the quality and quantity of filtered water. More contamination or water use requires more frequent backwashing. Note that Pyrolox filters do not reduce bacteria levels.

I estimated that a Pyrolox filter alone could reduce our Mn to acceptable levels. Two important things are required for a Pyrolox filter to adequately remove Fe, Mn and H2S without additional filtering systems.

1. Contaminant levels must be low enough for Pyrolox to work alone. If levels get too high (>10ppm Fe, >5ppm Mn or >3ppm H2S), another oxidation system like chlorination or aeration must be used along with the Pyrolox. Our Fe level was 0.29ppm (<0.3 required), and our Mn level was 0.089ppm (<0.05 required).
   
   
2. The well pump must produce a high enough flow rate in gallons per minute (gpm) to effectively backwash the filter. High backwash flow rates allow adequate precipitate removal and long filter media life. Our well pump produces 15gpm which meets requirements.
   

A Pyrolox filter backwash valve timer continuously uses electricity, but only about 1/3 that of the Triple O ozonator. With our low contamination levels, the Pyrolox filter media should last at least 15 years (probably much longer). The final factor that settled my decision was that the Pyrolox filter cost 1/2 that of the Triple O ozonator. In my opinion, the Pyrolox filter was a greener solution than an ozonator for Mn reduction in my specific application.

We purchased our Pyrolox filter from Clean Water Store in Santa Cruz. After installation, water quality testing showed that the Pyrolox filter reduced Fe to <.05ppm (a factor of 6 reduction) and Mn to <.o1ppm (a factor of 9 reduction). I have the money saved from this purchase to apply towards a bacteria filter to get equivalent performance of an ozonator. I'll cover that in a future post. Thanks for reading! Your comments are appreciated.