By Melissa Lubitz
Within the last five years water scarcity has been, and will continue to be, a topic of the highest priority. Do we have enough water? Are we consuming it at an alarming rate? Where do go for more when it’s gone? What are our alternatives?
One prevalent method of bringing drinking water to the people of the world where conventional water systems do not meet their needs is the use of rainwater collection catchments. Rainwater catchments have been used for many years all over the world and can simply be described as the gathering and storage of rainwater.
This collection method, however, can only be effective if adequate water treatment is applied, especially if the water is being used as a drinking water source. Utilizing rainwater catchments can also aid in expanding our water resources even in areas of the world served by conventional systems.
Photo 1 – Residential catchment
Although rainwater harvesting has been practiced for thousands of years, it has now become a necessary solution due to global water shortage concerns. Catchments are used all over the world, with Israel starting the trend more than 2,000 years ago.
Due to the success of catchments in countries like Germany, regulations have been passed for such systems in order to ensure that consumers are protected from possible bacterial contamination when a catchment is used as potable water source. In some areas of the Caribbean, new houses are required to install catchment. And it has been reported that to date, Gibraltar has one of the largest rainwater collection systems in existence.
In the US, Hawaii is currently developing regulations for catchments, as they are being used increasingly across the islands due to the amount of rainwater that can be captured. There is a long established tradition of rainwater collection in some parts of Alaska. The city of Austin Texas now offers rebates for homes that utilize catchments.
Photo 2 – Residential catchment
Collecting rainwater for household use is quite efficient if the proper catchment has been installed. There are, however, some important considerations.
It has been shown that much of an average household’s water needs can be met by collecting rainwater without further purification. When it is being used for drinking water, proper water treatment methods must be implemented.
Although rainwater does come from the sky, catchment water should not simply be considered pure and safe to drink. During collection rainwater picks up dust and gas contaminants from the atmosphere. It also can become contaminated by contaminants of the rooftops from which it is collected and from storage containers where the water eventually ends up.
Extra attention must be paid to the storage of the water. Consumer must also consider turbidity from debris (leaves, dirt particles), taste and odors that may arise from catchment water storage.
Any exposure to the elements could elevate the contaminant level, specifically bacterial. Micro organisms may be present from possible animal droppings, inadvertent contaminants or elevated temperatures during times of storage.
Photo 3—Balehouse catchment
When researching different methods of water treatment, simple and inexpensive treatments can be considered based upon the amount of water that will be accessible to the home. When considering treatment of the catchment water, there are only four primary elements that come into play.
- The probability of high levels of bacteria, or Cryptosporidium (a major consideration in terms of treatment efficacy; is carried by birds and much harder to inactivate than bacteria.);
- Chemicals picked up from the atmosphere and rooftops, and what treatments will be needed to address them;
- Taste and odor of the water;
- And, turbidity levels.
When researching different methods of water treatment, this can be very simple and inexpensive. This is especially true when considering the amount of water that will be accessible to the home.
To eliminate turbidity, consumers will need some form of filtration. A simple search on the Internet will show the many types of filtration available.
Filtration for larger particles would merit a filter with a high rating of approximately 20 to 50 microns. Filtration for medium-sized particles (which are not visible to the naked eye) would require a standard-sized filter with a rating of approximately five microns. Fine filtration (ultrafiltration) will remove contaminants as small as viruses.
It is best in treating water from catchments that turbidity removal be handled separately from taste and odor removal. Taste and odor can be addressed with carbon filtration, but remember that particulate and carbon filters need to be replaced regularly.
For a residential application a simple, safe method of disinfection is also desirable. Ultraviolet disinfection is often the most viable solution. UV equipment can inactivate all micro organisms that may be present in the catchment water. This includes bacteria (E. coli, fecal coliform), viruses and protozoan cysts (Giardia and Cryptosporidium).
Catchment water treatment equipment should be plumbed as the water enters the home or facility so that all water in the system is as free from contaminants as possible. The consumer can consider installing the three main pieces of treatment equipment separately, or there are some manufacturers that do offer all equipment within one single device, making installation and maintenance simpler.
FIG 1 – SC320 installation
Filters in these types of systems typically need to be replaced every three to six months, depending on the level of debris and the taste/odor issues. The home owner will be able to easily recognize when it is time to replace the filters due to drops in water pressure, increases in odor and poor taste from the stored water.
It is very important to pay close attention to the filter change-outs, as filters are not only cleaning the water but also protecting the UV system. This ensures that UV lights are able to penetrate the water and reach all micro organisms present, ultimately rendering them inactive.
The UV system must be maintained on an annual basis with quartz sleeve cleaning and lamp replacement. This depends on the model of UV system installed and the manufacturer’s lamp replacement recommendations.
Photo 3 – Combined treatment system
A typical North American family of four uses 1,500 liters (400 gallons) per day of water for regular usage. Over a year this can add up to 550,000 liters (146,000 gallons) of water.
By utilizing rainwater, that volume remains in our water system, allowing for possible expansion of fresh water resources. In places of water scarcity this method of water collection can be vital for survival but only if it is safe for consumption.
As a water treatment dealer or a company dealing with water treatment equipment there is a tremendous opportunity in areas that utilize rainwater catchments. Although rainwater harvesting does not offer the possibility of replacing all sources of drinking water, it will be able to ease the pressure on surface water and groundwater usage as the primary source of drinking water.
As this water resource process is becoming common practice for residential homes, water treatment needs to be a prime consideration. While it is essential that applicable regulations and regulatory requirements also be met for residential catchment systems, having the knowledge of what is needed for safe, clean drinking water is the only tool required.
About the author
Melissa Lubitz, B.Sc., C.E.T., CWS-VI works as a Business Analyst with the Innovation Group at VIQUA, a Trojan Technologies company, in Guelph, Ontario. Lubitz started with R-Can Environmental eight years ago, heading up the technical support team, prior to the company becoming VIQUA. She is involved with corporate training, validation coordination, regulatory compliance as well as market research and strategic planning.
About the company
VIQUA is the newly formed organization of Trojan Technologies residential water service and R-Can Environmental. VIQUA represents over 50 years of service as a respected, leading provider of UV water treatment technologies. Leading brands Sterilight®, TrojanUVMAXTM and Advanced Water ProductsTM are still backed by the same skilled group of water treatment professionals.
- Photo 1 courtesy of ersson.sustainabilitylane.com/rainwater.htm.
- Photo 3 courtesy of AB-Pacific Blue.
- Graphic 1 courtesy of www.rainwatercollection.com.