All posts by Ken Blair

A rainwater collection systems designer and consultant, Ken has designed and installed residential and commercial systems, primarily in the northwest United States for more than 10 years and, in 2014, began consulting and managing builds in other states. Ken is an accredited ARCSA Professional Designer / Installer and Life Member, the Northwest Regional ARCSA representative and advisor to its education committee and is available to speak about Rainwater Collection Systems design and builds. Ken is a United States Navy veteran, having served on active duty during the Vietnam War era. A career entrepreneur, Ken created a new business focus with a commercial dive company in Hawaii in the mid 1980′s to respond to and clean up oil spills, oil spill equipment training, service and maintenance for the oil co-op service industry. Ken is passionate about having a positive impact on the environment and is also a founding director of BANK-ON-RAIN (2011-2014), whose mission is to create grassroots solutions for rainwater collection for consumption and agriculture in developing areas of the planet.
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.

Rainwater Catchment, Rainwater Harvesting Education

What Causes Discoloration in My Water?

organic matter in waterTannins in drinking water are caused by natural decaying of organic matter. Leaves or pine needles in the gutters are generally the cause in a rainwater collection system.  A faint yellowing of water generally occurs at .5 parts per million or PPMs with .5 – 2.0 PPMs looking like the color of ginger ale, and 3.0 – 5.0 PPMs would take on the appearance of dark tea. The tannins may cause a yellow color of the water, yellow staining on fixtures, and yellow staining in laundry.

Although aesthetically displeasing, tannins generally pose no real health risk, but may affect the performance of the UV system by not allowing the UV light to penetrate thoroughly through the water column.

Therefore, it is very important to minimize tannins before storage of collected rainwater. Organic matter must be kept from accumulating in gutters, down spouts, and screen baskets. Gutter screens are an effective method of prevention of organics in gutters and down spouts. Both gutter screens and screen baskets should be inspected and cleaned as needed to prevent tannins from occurring. Since the discoloration is in solution, removal can be difficult and expensive. Ozone, ion exchange, and activated carbon can help with removal of tannins to some degree. If you do end up with tannins in your water, it is best to drain the cisterns, rinse and start collection again, however the best solution is diligence in maintenance.

Residential Rainwater Collection

How to Achieve Potable Harvested Rainwater with UV Disinfection

file0002019685404UV disinfection is the most common method used in residential rainwater collection systems.

UV light is generated by  supplying voltage across a mixture of gas, causing a discharge of photons, disrupting the DNA of microorganisms which prevents them from reproducing.  If the microorganism cannot replicate, it cannot infect, so viruses, bacteria, Cryptosporidium and Giardia cyst threats are effectively reduced.

A residential UV system typically consists of a power supply (ballast), a UV lamp housed in a Quartz sleeve inside a stainless steel chamber. The flow is directed close to the UV light while passing through the chamber. Effects of turbidity or clarity of the water before entering the chamber must be reduced by proper filtration upstream. Sediment and carbon filtration is used to reduce solids and solution contaminants, which can reduce the effects of UV disinfection. Filtration and UV bulb most be routinely changed in order for all to work effectively. It is recommended to follow manufacturer’s instructions closely, and filters should be changed out as needed.

Some UV systems offer an alarm or sensor with solenoid shut down if the UV system is not working properly. A class “A” UV is the only system considered to purify water that has NOT been deemed “safe to drink”, therefore caution is recommended in the use of a class “B” filter which maybe more tempting to use because of price. The difference between the two is the dosage of the UV light; the lower dose is not as effective in disinfecting. If a more advanced filtration system is used prior to disinfection, you can increase the effectiveness of the class “B”, but caution must be taken for proper results.

UV disinfection provides a relatively low cost, dependable, efficient, chemical free method of water purification that the homeowner can operate to disinfect his or her water supply.

With proper design, installation, and maintenance, clean, safe, and dependable potable water can be achieved from UV disinfection and rainwater collection.