ISH displays common-sense rainwater and gray-water systems that stretch potable water supplies.
BY DAVE YATES
SPECIAL TO CONTRACTOR
Potable drinking-quality water comprises just one-half of 1% of the earth's available water! Millions of people throughout the world will go without a single source of clean drinking water today. We're seeing areas of our own country that have reached, or are already in, the beginning stages of a full-blown water crisis.
Large-scale desalination plants are being tested and built to generate potable water. If you live in a home with a roof over your head, you have a natural conduit for gathering, maintaining and utilizing nature's hydraulic cycle — rainwater!
Rain on the roof
At the ISH trade show in March in Frankfurt, Germany, numerous vendors displayed "regenwasser" collection, storage and use systems. They run the gamut from decorative columns to plain-Jane tanks for above-grade systems; to underground storage vessels designed for direct burial that incorporate man-ways for accessing components.
A common theme seen with each manufacturer's presentation are the following construction details: screening out organic debris and man-made objects such as tennis balls, which are ejected via a side debris chute — while allowing uninterrupted free passage of the water; gentle entry of collected water to promote settling; pumps with screened floating suction-intake to draw water from the most sedimentfree upper layer while preventing any large particles from entering; and filtration and ultraviolet sterilization, which are typically utilized just ahead of entering the home's distribution system. Chlorination is discouraged due to the presence of organic material, which can combine to create chlorinated hydrocarbons, a carcinogen.
A quick rule-of-thumb for rainwater collection for system-wide plumbing use is to size the container for 30- to 55-gal.-per-day-per-person (using 1.6 gpf water closets). In order to calculate the vessel's volume, you'll need to gather average rainfall data for your area and measure your roof's square footage. The roof's pitch will cause the volume of runoff to increase as pitch increases due to rain often being wind-driven. For example, a 4/12 pitched roof has a multiplier of 1.05.
Another quick rule-of-thumb for collection capacity is to take half of the roof's square footage and multiply that by the average annual rainfall. National rainfall maps can be utilized (http://www.noaa.gov/climate.html), but your local TV stations will likely have accurate data that may be a bit more precise. An average rainfall in excess of 24 in. will be adequate for you to be self-sufficient if your storage vessel is large enough to tide you over between storms. Virtually all of the eastern half of the United States and many parts of the West have annual rainfall in excess of the minimum.
Roof materials can be a concern. Wood shingles can leach chemicals; asphalt shingles can release petroleum products; metal roofing may be coated with lead-based paints (lead is readily adsorbed through skin during bathing); and there is always the issue of animals such as squirrels and birds leaving deposits behind that will be mixed into the collected water. Materials other than metal can support and foster mold, bacterial and algae growth too.
More advanced rainwater collection systems have built-in features to "waste" the first bit of roof runoff to greatly reduce contaminate collection. Metal roofing sheds more rain than do any of the other materials (about 10% to 15% more).
Local plumbing code authorities may have reservations about your use of rainwater for a primary or secondary potable source, which may be partially driven by a perceived loss of revenue as many sewage treatment bills are based upon gallons delivered via the municipal water meter reading. Other concerns may center on issues about maintaining potability.
You may want to point out that all potable water began its journey to your home as rainwater. With filtration and UV sterilization built into these modern automatic systems, the only remaining issue (beyond roofing products) should be standardizing maintenance and that's an area ripe for maintenance contracts. Well-maintained systems that are properly designed and installed by professionals will not pose a threat to the potability or our customers' health.
If local code bodies are worried about water quality with rainwater systems, wait until they have to face the issue of recycling gray water! The notion that every flush of a water closet utilizes drinking-quality potable water has always gone against the grain of common sense. As water becomes a more precious resource and expensive commodity, alternative sources will inevitably become widely accepted and utilized.
While at ISH, I visited with Pontos and had an opportunity to discuss gray-water recycling issues. According to Pontos (www.pontos-online.de), a subsidiary of Hansgrohe, gray-water (free of any fecal matter) collection from residential use more than adequately meets demand for flushing toilets, washing clothes, watering gardens and washing vehicles. The Pontos motto "Use your water twice — it's the smart way!" certainly makes sense to me. Pontos coupled a rainwater and graywater modular collection system to serve a residence and beauty salon, which was chosen for its higherthannormal demand for flushing toilets and almost-constant use of clothes washers. Pontos' combination recycling system was awarded the ISH 2005 Innovation Award for Architecture and Engineering!
My first concern was regarding odors from collecting and storing wastewater, but that's handled through natural bacterial processes without the use of chemicals. I next inquired about solids, soaps, grease and hair as they're all going to be a naturally occurring issue in any gray-water system. No problem — they're collected and rejected to the home's black-water drainage system. Bacteria in the delivery "polished" water stream? That too is dealt with by UV sterilization.
In fact, the delivery water is in full compliance with the European Union directive for bathing water (http://europa.eu.int/water/water-bathing/directiv.html). Well, OK then, the expense has got to be a real deal-killer, right? Wrong again.
"Currently, the annual savings after deducting the low operating and maintenance costs for the AquaCycle system is 570 Euros ($730 U.S.)," according to Pontos. "This means that considering all of the factors, the purchase of the system will, in all probability, have paid for itself in only seven years."
Keeping up with demand isn't an issue either as Pontos has models ranging from 238 to 3,302 gal. per day recycling capacity. One advantage gray water holds over rainwater is that it's not dependent upon weather patterns.
Pontos has tracked costs for plumbing the drainage to separate gray-from black-water lines and has seen a historical average of 400 to 600 Euros ($512 to $769 U.S.). All water lines carrying recycled water must be clearly marked " not drinking water" and made discernable along their entire length by a distinct color.
As plumbing contractors, we share an obligation to protect not just the health of the nation but also the environment. Our code bodies will need to readjust their stance on gray-water recycling systems as this newer technology enabling clear, clean, odor-and bacteria-free water emerges.
Conservation of natural resources, reduced demands placed on sewage treatment and delivery of municipal potable water, plus working in concert with Mother Nature — that's about as good as it gets. Even Mr. Natural would be striding along with a smile on his (by now) grizzled face!
Dave Yates owns F.W. Behler Inc., a contracting firm in York, Pa.