Monthly Archives: February 2015

Infrastructure, Rainwater Catchment

Harvested Rainwater Reduces Energy Consumption

Ancient Istanbul Water SystemUtilizing the rain that falls on the roof of a building is a simple concept that has provided water to buildings for centuries, and continues as the primary source in many locations in the United States and around the world.

In places such as Bermuda and the US Virgin Islands, the harvesting of rainwater is required by local codes for all new construction. Also, states such as Hawaii and Texas have or are developing design guidelines for rainwater harvesting systems. Additionally, San Juan County in Washington State has been issuing building permits with rainwater as the sole source of water for several years.

Harvested rainwater is free of most of the pollution typically associated with surface water runoff. Furthermore, using harvested rainwater both reduces peak storm water discharge velocities associated with impervious surfaces and reduces the draw on aquifers and municipal water supplies.  Collected rainwater does not have to be pumped up from a well or be conveyed from a distant central treatment facility. This reduces energy consumption, reduces the use of chemical treatment and disinfection as well as it is less disruptive to the natural hydrologic cycle.

On October 12, 2009 the Washington State Department of Ecology issued an Interpretive Policy Statement clarifying that a water right is no longer required for roof top collection. Since January 25, 2011, King County has adopted rainwater harvesting for potable use in single family residences as a supplemental water source. Other Washington State Counties have since adopted rainwater collection for potable use in single family residence as well.

Ancient Istanbul Water System courtesy of David Malloy

Infrastructure

Would You Drink Poop Water?

From Poop to Potable

Bill Gates challenged a group of engineers to come up with an affordable way to get rid of disease-spreading sewage in developing countries where getting rid of waste is too costly.  The engineers rose to the occasion and developed a process called Omniprocessor, which makes drinking water from sewage.

Gates says “The water tasted as good as any I’ve had out of a bottle. And having studied the engineering behind it, I would happily drink it every day. It’s that safe.”

Watch as Bill Gates gets Jimmy Fallon to drink water made from poop.

How-to, Rainwater Harvesting Education

How to Keep Collected Rainwater Clean

Gutter screening, first flush devices, vortex filters – which is best suited for my rainwater collection system?

Cottage without gutter screen
Without gutter screen

If you have been following my last few posts, you can start to understand the need to be sure that your collected rainwater is clean before it goes to storage. Keeping it clean will help keep tannins to a minimum, prevent debris from entering your cistern, and will also mean less demand on your filtration and disinfection systems.

With Gutter Screen
With gutter screen

Gutter screens are the first line of defense to keep your collected rainwater clean before storage. It is well worth the expense to purchase quality gutter screens to start with. Typically, an aluminum frame with stainless steel meshing works the best. They are expensive, but will make maintenance of your system much easier. Stay away from the low density foam insert types, they only clog up with debris and turn septic quickly. Light sheet metal type framing for screens tends to bow in the middle from the weight of the water. So spend some money up front and you won’t need to clean gutters.

A first flush device, or vortex filter is the second defense against debris from entering your rainwater system cisterns.

first flush device
First flush device

A first flush device is a vertical 3” or 4” vertical pipe that has a ball inside that will float to the top of the pipe as the initial water fills. When the ball gets to the top of the pipe, it closes off the vertical pipe and allows the water to move horizontally through a “t” and sends cleaner water to the cistern. The water at the cistern should go through a screen basket before entering the cistern for added protection.

vortex filterThe vortex filter is more of a hands-free device instead of the first flush and for most applications, this designer/installer prefers it. The vortex filter works on a centrifugal theory, where the water enters the top side of the filter from the tight line and is directed into a channeled side which swirls the water horizontally, passing through a screen, then towards storage. Residual water along with the debris falls through the center and towards waste. Only occasional cleaning of the screen is needed for maintenance, making this system as hands off as can be.

Things to consider when choosing a pre-screen system are:

  • Are my gutters hard to get at, are they second story?
  • Do I have a large amount of trees that shed needles and leaves to my roof or gutters?
  • Are my downspout lines connected to tight lines which convey water to the cisterns, or do they gravitate into the top of the cistern?
  • Am I willing and able to care for my first flush devices by maintaining their cleanliness?
  • Do I live in an area that is prone to sub-freezing temperatures?   

 If you have questions, or would like a specific topic covered, let me know in the comments.