Tag Archives: Ultraviolet light disinfection

Rainwater Catchment

Building a Potable Rainwater Collection System

sun-11129_640There are several stages to building a successful, potable rainwater collection system. Here is an article originally published in June 2014, under the title Ultraviolet Light Disinfection For Rainwater Harvesting. (Also see “How to Build a Rainwater Collection System, parts one, two, three, four, five, six, seven and eight.)

The final stage of treatment for a potable rainwater collection system is ultraviolet light disinfection (UV). Effectiveness of the UV system is determined by a few factors.  First, pre-filtration, which includes a sediment filter and a carbon filter that need to be upstream of the UV. This will help ensure the clarity of water entering the UV chamber, enabling the UV rays to penetrate the water stream.

When UV energy is absorbed by the reproductive mechanisms of bacteria and viruses, the genetic material is “rearranged” and can no longer reproduce, with risk of disease eliminated.

There are 2 classifications of UV light determined by the dosage of the UV light itself, and a class “A” UV is the only class recommended for disinfection of rainwater collected from a rooftop.

The American Water Works Association describes a class A ultraviolet system as an effective method of disinfection for water that is not determined safe to drink. A class B ultraviolet system is only effective for water already deemed safe to drink – such as a water source already treated with chlorine.

An alarm and or solenoid valve for system fail safe is always a good idea to include with your UV system. This method will shut down the system or sound an alarm if a sensor determines the water turbidity (clarity) is not sufficient for proper UV absorption.

Ultraviolet light is a natural, cost effective environmentally safe method of disinfecting drinking water as long as it is properly maintained and the bulb is changed according to manufacturer’s recommendations.

As always, before you take on a rainwater harvesting project, know the rules in your state, county and municipality. It helps to work with a RWC pro who can help you through the process, saving you time and money along the way, while also ensuring that the result is a functioning and safe water collection system that will serve you for many years.

Commercial Rainwater Harvesting, Rainwater Catchment, Residential Rainwater Collection

Rainwater Collection is Ramping Up

In a recent article for Forester Network, about the growing rainwater collection industry, ARCSA president David Crawford says, “The field is really ramping up…”

The article goes on to explain, “There are a variety of methods of collecting rainwater – rain barrels, aboveground or underground cisterns, and other collection devices. Such harvested rainwater is frequently used for irrigation, but can also be a source of water for flushing toilets, washing vehicles, and, in some cases, for drinking water.”

Starting off the year by hitting the ground running, RainBank Rainwater Systems of Seattle is currently designing and building systems from Portland, Oregon to Whatcom County, Washington.

As the industry grows beyond a small niche market and becomes mainstream, RainBank has met the call for new steel water tank options in the Washington commercial and residential market with Contain Water Systems Inc – which carry a 20 year, industry high, warranty.

1-onequarter inch coarse filter_RainBankA dealer for Wisy products, Davey Pumps and Viaqua ultra violet disinfection systems – are all available from RainBank (contact us for more information). Additionally, RainBank recognizes the need for ease of ordering rainwater system components online from a local dealer and is continuing to build its website shopping cart.

RainBank Rainwater Systems has 15 years experience in the rainwater harvesting industry and is recognized by top engineering firms, architects and builders in the Pacific Northwest for consulting, design, and construction as the most knowledgeable, experienced, and trusted firm available. Contact RainBank today.

Rainwater Catchment

Is Rainwater Safe to Drink? What About Bird Poop?

RBRWC924155As an American Rainwater Catchment Systems Association (ARCSA) Accredited Professional and Inspector Specialist, I’m often asked,

“Is rainwater catchment water safe to drink? What about the bird poop?”

Which usually evokes my typical response “Certainly it is, with proper storage, filtration and ultraviolet disinfection (UV), your quality of water will more than likely exceed the quality of municipal and well water sources.” Rainwater is relatively clean to start with; it is what it comes in contact with, how it is stored, and how it is treated which determines its quality.

Wells, lakes, and rivers are the most common source of our municipal water supplies. “It’s the same bird that just pooped on my roof that just flew over the lake”, I exclaim, “and as for droppings questions about deer, raccoon, geese, and every other forest animal out there – I have yet to see a deer or goose on my roof.” I often am rewarded with an ever so slight chuckle, but it does get the attention of and makes sense to my new rainwater collection advocate.

Municipal, well, and private rooftop collection must address coliform and bacteria. Municipal water sources typically use chlorination and ultraviolet disinfection to achieve an expectable level set by the EPA. Well water that exceeds allowed bacteria and coliform levels are usually condemned.

Properly collected rainwater has relatively low levels of bacteria and coliform, lending itself to simple disinfection with ultraviolet light exposure. Advances in small ultraviolet light systems, designed and tested for household use, have made potable household use of collected rain virtually free of bacteria and coliform. Of course, filtration prior to disinfection needs to be addressed by municipal, private well, and private roof top collected water. Most private rainwater catchment systems mimic municipal water filtration techniques with sediment and carbon absorption filters, followed by disinfection. Unlike well water, there is never a concern with rainwater catchment for iron, hardness, salinity, or other constituents that would require additional filtration.

file0002019685404Any source of water, whether municipal, well, or rooftop collection, must be properly maintained and monitored. Private well maintenance is typically conducted by the owner – consisting of filtration changes as needed, and testing -being conducted at time of commissioning, or as a disclosure during the property sale. Municipal water sources are maintained and monitored by trained personnel, but allow for higher levels of constituents than a properly designed, constructed, and maintained rainwater catchment system. Once again, rooftop collected water is relatively clean to begin with, therefore requires a less aggressive approach to filtration and disinfection than that of a well or municipal water source. The homeowner easily maintains a rainwater collection system with periodic filtration changes, annual testing and simple monitoring. You become the purveyor of your water source; you are in charge, not leaving it to others.

With careful consideration of materials, techniques, and maintenance, rainwater is most certainly a viable source of clean, safe to drink, water.