Reclaimed Water and the Codes
While it is recognized that potable water is an increasingly fragile resource in the United States, the issues of water-conservative fixtures, rainwater harvesting, water recycling and reclamation are only just starting to be addressed by codes and regulations. The recent surge in green building is bringing the issues into focus as plumbing engineers and building and code officials attempt to i...
While it is recognized that potable water is an increasingly fragile resource in the United States, the issues of water-conservative fixtures, rainwater harvesting, water recycling and reclamation are only just starting to be addressed by codes and regulations. The recent surge in green building is bringing the issues into focus as plumbing engineers and building and code officials attempt to interpret existing code language to accommodate new system technologies and water-conservative fixture designs. Global warming adds additional uncertainty.
One thinks it's just water, but the issues of water chemistry, including chemical and biological aspects, are complex and all water is not created equal. Everything ends up in the water at some point. Water is polluted by sewage and agricultural runoff, industrial waste, mine and landfill leachates, acid rain, erosion sediment, and asphalt runoff. Water carries salts, metals, and minerals, dissolved organic and inorganic chemicals and pollutants, organic materials and waste, algae, simple organisms, bacteria, viruses and parasites. Depending on its chemistry, water must be treated to different degrees before it can be used for any application.
Potable water, which is highly treated, disinfected and filtered, is the only water suitable for consumption and agriculture, and for many institutional and industrial processes that require reliable water chemistry. However, typical uses range from sanitary conveyance (flushing) through the sewer systems, to cooling steam condensate, maintenance or other industrial procedures where non-potable water might suffice.
Recycled or reclaimed water is wastewater that has been treated and disinfected to tertiary standards, which is the same as water treated by municipal sewage treatment plants. It is suitable for discharge into rivers or into groundwater, but is not potable. EPA guidelines, state departments of environmental protection and municipal health departments prescribe the uses of non-potable water. The basic approach with recycled water is to prevent the public, livestock, plants and foodstuffs from coming into direct contact.
In buildings, the Uniform Plumbing Code Appendix J permits reclaimed or recycled water usage for toilets, urinals and trap seal primers that must be piped as a separate system from potable water with suitable precautions against cross-contamination. Reclaimed water is wastewater that has been treated to tertiary standards. The latest International Plumbing Code 2006 Appendix C (part of the International Building Code) addresses graywater usage for water closet and urinal flushing, as well as subsurface irrigation. Graywater is defined as wastewater discharged from lavatories, bathtubs, showers, clothes washers and laundry trays. Graywater may not be stored for greater than 72 hours when used for flushing, and 24 hours when used for subsurface irrigation and must be disinfected with chlorine, iodine, ozone or ultraviolet irradiation. It must also be dyed to differentiate graywater from potable water and suitable precautions must be taken against cross-contamination.
Water may be reclaimed from graywater, sanitary or black water, HVAC condensate, process or rainwater. On-site building treatment systems, such as ultrafiltration can filter down to virus levels, and “living machines” or engineered reed beds can be designed to filter industrial or sanitary wastes, resulting in tertiary level reclaimed water. For any additional usage in the building beyond toilet flushing, including cooling tower makeup, irrigation or sidewalk cleaning, where the public might come into contact with the reclaimed water, it must be further treated and disinfected using chemical treatment and methods such as reverse osmosis (RO) to insure potable quality water. In addition, reclaimed water derived from sanitary waste tends to build up salt content through multiple reclamation cycles, which would interfere with cooling tower water chemistry, irrigation, or maintenance uses.
Rainwater harvesting has not yet been addressed by national or state codes. A vegetated roof can capture close to 50% of the volume of rain that lands on the roof surface, which reduces the strain on municipal stormwater systems, but the remainder is still stormwater. If the rainwater is collected for use within the building, local officials may consider it through the alternate materials and methods section. However, it is typically considered to be recycled, and falls under the usage guidelines of the national and state codes, which limit its use to toilet flushing and subsurface irrigation. In some instances, local health requirements may be more stringent, not allowing use of non-potable water for irrigation.
While at first it may seem nonsensical that what was just moments before considered rainwater is now recycled water that cannot be used to wash the sidewalk, the rainwater has potentially picked up soot, bird and rodent droppings, insects and chemicals from roofing products. Once stored for future use, the water could cultivate bacteria and viruses, unless disinfected and filtered, so the reclaimed designation is appropriate.
A number of states whose water supplies are at greatest risk, due to high demand, climate or decreasing supplies— with California, Florida, Texas and Arizona leading the way—are developing regulations that define levels of water quality, treatment and when and how reclaimed water can be used. They are also adapting plumbing codes to recognize emerging water conservation technologies for fixtures, such as dual-flush toilets, ultra-low flow pressure assisted toilets, low-flow shower heads, low-flow and waterless urinals, and low-flow faucets. But even states with plentiful water supplies, including Oregon, Pennsylvania, New York and New Jersey, are in the process of defining their reclaimed water regulations to protect and conserve their most precious resource. It also makes practical sense, since non-potable water can potentially be less expensive to produce and distribute.
Over the next few years, as the demand and stresses on our water resources continue to grow, we can expect to see better defined regulations and codes for water conservation and the use of recycled or reclaimed water, including rainwater harvesting. It is also likely that the rising costs of potable water will make reclaimed water an attractive business option. In some areas, notably California, highly purified recycled drinking water is being introduced for public consumption. We will all have to get over our psychological “yuck” reactions, and realize that the alternatives are far worse.
Desalination Through Reverse Osmosis
The reverse osmosis (RO) method of water treatment will be used on a large scale in a recently announced desalination project for South Carolina. Earth Tech, Long Beach, Calif., a business unit of Tyco Intl. Ltd. and a global provider of consulting, engineering and construction services, has been awarded a $5.5 million design-build contract by the Hilton Head Public Service District, the drinking water and reclaimed water utility for the north- and mid-island areas of Hilton Head Island, S.C., for the development of a new desalination facility that will increase access to affordable fresh water in the community.
Saltwater intrusion in the local aquifer has forced the utility to purchase almost half of its water from its wholesale surface water supplier in recent years. Earth Tech will design and build a new treatment facility, which will use reverse osmosis to treat up to 3 million gallons per day (mgd) of brackish water from the 600-ft.-deep Middle Floridan Aquifer, a new drinking water source for the island.
“Ensuring a reliable source of drinking water is an issue that many communities face,” said Bill Webb, executive vice president of Earth Tech's Global Consulting & Engineering business. “Our global expertise in designing water facilities, combined with our treatment technologies, will help Hilton Head meet the drinking water needs of its residents for years to come.”
Earth Tech's scalable design will allow the capacity of the plant to be doubled to meet future needs of the region. It will take approximately 18 months to design and build. The RO system will be constructed by Water & Power Technologies, a division of Earth Tech.
Earth Tech Inc. provides a full suite of engineering, construction and operations services to the international water/wastewater, environmental, transportation and facilities markets and employs some 7,000 people, delivering services to customers in 15 countries. Founded in 1970, the firm can be found on the Internet at
Tyco International Ltd. is a global, diversified company that provides vital products and services to customers in four business segments: Electronics, Fire & Security, Healthcare and Engineered Products & Services. With 2006 revenue of $41 billion, Tyco employs approximately 250,000 people worldwide. More information on Tyco can be found at