Code requirement is maximum 1/16” debris screen (10 mesh) before tank.
Code requirement is 100 micron screen after tank.
E. coli is a subgroup of the fecal coliform group. Most E. coli bacteria are harmless and exist in the
intestines of people and warm-blooded animals. However, some strains can cause illness. The
presence of E. coli in a drinking water sample usually indicates recent fecal contamination. That
means there is a greater risk that pathogens are present.
Total coliform bacteria are common in the environment (soil or vegetation) and are generally harmless.
Water quality of system could be improved by adding redundant debris screen (gutter guards) on gutters.
Turbidity is a measure of water clarity how much the material suspended in water decreases the passage of light through the water. Suspended materials include soil particles (clay, silt, and sand), algae, plankton, microbes, and other substances. These materials are typically in the size range of 0.004 mm (clay) to 1.0 mm (sand). Turbidity can affect the color of the water.
NTU =NTU = Nephelometric Turbidity Units
With only 276 ft2 of catchment surface, 4.4” of rain is needed to satisfy monthly demand of 687 gallons, and 6” of rain is needed to fill the cistern. Dec-March are the only months of the year when average rainfall exceeds 4.4”. The size of the cistern only provides a 37 day supply. Options to improve water savings are to increase catchment surface area, increase storage capacity, or invest in a higher efficiency clothes washer.
Live Oak Residence uses a total of 4.25ccf/month for indoor uses, or 51 ccf/year (38,148 gal/year).
Note that water savings from greywater system is not counted in rainwater system savings because landscape irrigation is not normally not necessary during the rainy season (Dec-March), with the exception of winter drought. However, 687 gal/month of greywater is available during the 6 month irrigation season (April-October). The clothes washer greywater system provides an additional 4,122 gallons of water savings when greywater replaces potable water for irrigation. Total materials cost for the clothes washer greywater system is $150.
$0.68/gallon = year one, Installed cost based on total average annual rainwater use of 2,748 gal (3.67 ccf)
In 2015, City of Santa Cruz Water Dept. delivered water in Tier 1 for $2.42/ccf (outside City limit)
With rainwater supplying 3.67ccf, annual savings = $8.69/year
Payback period = 209 years.
With a rebate incentive of $0.50/gal of storage, the payback period is reduced to 164 years, assuming the price of water remains the same.