We live in a time when many parts of our planet are experiencing water shortages. The volume of water on this planet is finite while human population increases. As we gauge the depletion of our aquifers and the increase in population, we are able to predict serious water shortages in the near future.

Fresh, Potable, Drinking Water

To further compound the water problem on this planet, we have polluted and contaminated most of our easily accessible surface waters and are beginning to contaminate the more difficult to access aquifers beneath the surface of the our planet. This contamination happens because of the way conventional sewage systems operate.

catchwater cistern interior

The following calculations do not include landscaping, washing cars, etc. This only covers defined uses within the building to illustrate the fresh water use difference between a conventional building and a sustainable building. These ‘sustainable’ water using methods can be implemented while still providing all of the expected modern expectations relative to the use of the building.

Generally speaking, a sustainable building with the methods outlined uses about half as much fresh, potable, drinking water as a conventional building.

Textbook-Cover-3D-water
Catch Water Book: Drinking, Cleaning & Bathing. Digital Download.

Catch Water Book: Drinking, Cleaning & Bathing.
Digital Download.
click here. get it now.

($50 until November 30, get it now. normally $75.)

59 pages with graphs, charts, images and diagrams explaining ALL aspects of water. Drinking, Bathing & Cleaning with Water from the Sky with municipal water supply. Residential buildings and Commercial buildings and Government buildings. This is the pathway to total and complete water sustainability, way beyond LEED.

  • Steps to Reduce Water Use
  • Water Use Calculation
  • Catching the Water
  • Rain Water Harvesting Supply Calculation
  • Cisterns
  • W.O.M. – The Water Organizing Module
  • How to build the WOM
  • Drinking Water
  • Heating Water: Solar Hot Water

click here for the complete Table of Contents

Catching the Water

Water is caught from a roof with a potable surface. From the roof, the water is channeled through silt catches into cisterns. Cisterns are sized to the local climate and are best buried and completely protected from the sun. The water from the cistern is gravity-fed into a Water Organizing Module with a pump and filter. The pump pushes the water into a pressure tank to supply code required water pressure. The filters clean the water for consumption and cleaning.

catch water organizing module

Rain Water Harvesting Supply Calculation

Rainwater harvesting calculators are important for several reasons. They help to better balance the supply and demand so that a system can be sized correctly and so the user has adequate storage to get through long periods without rainfall. This calculation determines stored water volume over the course of three years and whether supplemental water is needed.

For every square foot of roof, about .6234 gallons of water can be caught from 1 inch of rain.

total rain precipitation per month: 6” (example)

total rain precipitation per year: 72” (example)

1 square foot with 1 inch of rainfall catches .6234 gallons of water

size of roof: 1,000 sf (example)

1,000sf x .6234gal. = 623.4 gallons of water caught per inch 1 inch of rainfall.

623.4gal. x 72 inches of rainfall = 44,884.8 gallons of rain water.

In this example, we now have 44,884.8 gallons of water caught and available to use in one year. This is a calculation based on forecasted number which are based on probabilities and statistics using data from decades and decades of weather logs and research. As long as the model remains consistent, these calculations should be accurate enough.

To determine how much water can be used on average per day, divide the total available gallons of water by 365 days.

44,884.8 / 365 = 122.9 gallons can be used per day.

The following comparison of water use with the calculated water available in the example is very telling. Both buildings provide sufficient design and amenities for modern day living. The sustainable home could be a more conducive environment for working. Regardless, both buildings are at least adequate. The contrast brings up some powerful issues considering the state of the world we live in today.

Using the fresh, potable, drinking water use calculation outlined, two people in a sustainable building use, on average, about 30 gallons of fresh, potable, drinking water per day. For this example, these two people would have, on average, about 92.9 gallons of water left over. This is good, and this example is in a very wet climate.

4 people use about 60 gallons per day, 32.9 gallons leftover

Using the fresh, potable, drinking water use calculation outlined, two people in a conventional building use, on average, about 118 gallons of fresh, potable, drinking water per day. For this example, these two people would have, on average, about 4.9 gallons of water left over. This is not good and is at a high risk for running out of water, and this example is in a very wet climate.

4 people use about 236 gallons per day, 113.1 gallons in deficit.

Cisterns

The cistern is an integral part of a sustainable building. The cistern can also perform as a heat-sink to help keep the building comfortable. Cisterns can also be designed inside with waterfalls.

Water is caught from a roof with a potable surface. From the roof, the water is channeled through silt catches into cisterns. Cisterns are sized to the local climate and are best buried and completely protected from the sun. The water from the cistern is gravity-fed into a Water Organizing Module with a pump and filter. The filters clean the water for consumption and cleaning. The pump pushes the water into a pressure tank to supply code required water pressure. Can have city water as backup.

Size the Cisterns Appropriately

Climates with large amount of time of no rain at all require cistern water storage capacity sized to hold and store enough water to get through the large amounts of time of no rain. Using the calculations outlined, cistern water storage capacity can be calculated. Cistern types and installation is covered in the cisterns section.

When does the rain fall? In some areas, all of the annual rain happens in six months and the other six months is completely dry. This must be accounted for.

Dry Climate

Large cisterns with big silt catches that do not overflow. Never waste any fresh, potable drinking water. Absolutely no potable drinking water overflows.

Wet Climate

Relatively smaller cisterns. It is ok to overflow as there is more rainfall. Smaller cisterns only save money and that is ok. Generally, in every situation, large cisterns are highly recommended. Water is critical, absolutely critical.

A minimum of 5,300 gallons total storage capacity 

Advised for sustainable buildings in climates receiving at least 10” if rainfall per year with no other source of fresh, potable, drinking water.

There are several different types of burial cisterns on the market. This sizing is based on annual rain fall in your area, how it is dispersed throughout the year, roof size and projected use.

Gravity Feed

The water from the cistern is gravity-fed into a Water Organizing Module with a pump and filter. Therefore the bottom of the cistern is at the same level as, or higher than the pump on the WOM. This helps the pump to perform more efficiently and last longer.

If the power goes out, you will still have water to the sinks and to flush the toilet.

When the power goes out.

  • The fresh water supply line valve under the toilet tank should be switched to the ‘on’ position.
  • The grey water supply line valve under the toilet tank should be switched to the ‘off’ position.

Textbook-Cover-3D-water

Catch Water Book: Drinking, Cleaning & Bathing.
Digital Download. click here. get it now.

($50 until November 30, get it now. normally $75.)

59 pages with graphs, charts, images and diagrams explaining ALL aspects of water. Drinking, Bathing & Cleaning with Water from the Sky with municipal water supply. Residential buildings and Commercial buildings and Government buildings. This is the pathway to total and complete water sustainability, way beyond LEED.

Table of Contents

  • Water
  • Steps to Reduce Water Use
  • Fixing Leaks
  • Fresh, Potable, Drinking Water Usage
  • Conventional home use calculation
  • Sustainable home use calculation
  • Catching the water
  • Rain Water Harvesting Supply Calculation
  • Roof, Slope and Gutters
  • Roof
  • Slope
  • Gutters
  • Silt Catch
  • Cisterns
  • Size the cisterns appropriately
  • Gravity feed
  • Types of Cisterns
  • Tire Cistern Construction/Installation
  • Plastic Cistern Installation
  • Plumb the Cistern
  • Insulate & Bury The Cistern
  • WOM: Water Organizing Module
  • the WOM
  • Installing the WOM
  • Plumbing in the WOM
  • WOM Electrical
  • Initial start up
  • Parts and Pieces: Assembly
  • Spin-Down and Sediment Trapper Filters
  • Plumbing for Potable Drinking Water
  • Drinking Water Filter
  • Distribution
  • Multi-Candle Filter Module
  • The Do It Yourself Water Organizing Module Costs.
  • Heating Water
  • Why Use Solar Water Heating?
  • How to Use Solar Water Heating
  • Get Started with Solar Water Heating
  • Active Solar Water Heating Systems
  • Passive Solar Water Heating Systems
  • Storage Tanks & Solar Collectors
  • Selecting a Solar Hotter Heater
  • Evaluate Your Site’s Solar Resource
  • Determining the Correct System Size
  • Building Codes and Regulations for Solar Water Heating Systems
  • Heat Transfer Fluids for Solar Water Heating Systems
  • Reduce Hot Water Use for Energy Savings
  • Water System Maintenance
  • Gutters
  • Silt catch
  • Cistern(s) maintenance
  • WOM Service And Maintenance
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