Water Conservation Efforts
Unwittingly Leading to 'Dry Drains'

By Ron George, CPD,
President, Ron George Design & Consulting Services

Many experts agree there are a multitude of factors contributing to water shortages in many areas of the world. These factors include: global warming, increases in population, lack of proper water utility infrastructure, wasteful practices and underpriced water. We will never run out of water because water is constantly here in the hydrological cycle, evaporating, condensing into rain and falling to earth and flowing into the ground as groundwater. The run-off flows into streams, rivers and lakes for surface freshwater and into the ocean where it mixes with salt water. The key for us is to learn how to manage the fresh water resources we have and learn what those limits are in various arid or tropical regions of the world. The things that are occurring that are making water scarce are overdevelopment in arid regions, increases in population and lack of planning for infrastructure to keep up with population growth and shifting climate zones. With increases in population, we need to divide the fixed amount of fresh water available with each additional person and have a good understanding of that dynamic. In many cases proper pre-planning can allow additional reservoir capacity to store more fresh water, which requires acquiring land building dams, treatment facilities, pumping stations and water mains.

The United Nations conducted a study on the total amount of world water and it gave a breakdown of the freshwater resources. The study shows that 97.5 percent of the Earth’s water is saltwater and 2.5 percent is fresh water. They went on to break down the 2.5 percent freshwater to show about 70 percent of the fresh water is trapped in ice and snow cover in mountainous regions and polar ice caps. About 29.7 percent or 30 percent is in groundwater and the remaining 0.3 percent is available to us in the form of fresh surface water in rivers, lakes and streams. We actually have access to a significant percentage of groundwater and all of our surface water resources. Many areas of the world remove water from the groundwater reserve through water wells. Other areas with access to rivers, lakes and streams draw water from those resources. Troubled areas of the world are the arid parts of the world that get very little rain. The small amounts of rain they get could be managed better, or desalinization plants could be used to desalinate seawater with reverse osmosis treatment systems. This is not a very good option for areas way from the coast but many coastal areas could use seawater as a freshwater source, but few are willing to invest in the technology and energy required to do so. Just down the street from my office, there are two manufacturing facilities that make desalinization equipment. Their biggest customers are in the Middle East where there has been a building boom in arid regions such as Dubai and Saudi Arabia. If large reservoirs were constructed, it would be important to make the reservoirs deep and narrow to minimize the surface area of the water. Large surface areas would contribute to evaporation when there are long dry periods. Construction of covered storage facilities or deep surface water reservoirs in arid regions would require a significant infrastructure investment for arid regions, but could help catch the few rains they get each year.

Other concerns are maintaining a minimum water flow in a stream or river to maintain the aquatic life and vegetation downstream. As more water is captured for fresh water reservoirs, it affects the economies and environment downstream. I can see this issue becoming more political as rivers that flow across international boundaries are dammed and the resources become more important and more political. It might not be too far fetched to see a war fought over water in the not too distant future.
Water uses

According to a U.S. Geological Survey conducted by the Environmental Protection Agency, 87 percent of the water use in the United States is for non-residential water use. This includes agricultural, industrial and commercial uses. Industrial water uses include water used for fabrication, processing, washing, food production, cooling, and it also includes water used by smelting facilities, petroleum refineries and industries producing chemical products and paper products.

Large water users include the industries that produce metals, wood and paper products, chemicals, gasoline and oils. Just about every manufactured product uses water during some part of the production process. Other industrial water uses include: water used for such purposes as washing, diluting, cooling or transporting a product. Some uses incorporate water into a product, or for sanitation needs large amounts of water is used to wash down equipment, rooms and floors within the manufacturing facility in food processing plants, meat packing plants and dairy processing plants. Other industries that use large amounts of water produce such commodities as paper pulp for a variety of uses like diapers, facial tissue newspapers and other paper products. Water is used in chemical plants, for condensing towers in refineries and petroleum plants, or cooling water for primary metal processing plants. Irrigation water use includes water used for growing crops, frost protection, chemical applications, weed control and other agricultural purposes, as well as water used to maintain areas such as parks and golf courses. Other uses include private water wells, livestock, aquaculture, fish hatcheries and mining activities. Electric power accounts for a significant use of water withdrawals. Most of the water is derived from surface water and used for once-through cooling at power plants. In a few cases, lakes are built specifically for cooling water for power plants. The water in these lakes cannot always be used for other fresh water uses because the lake level must be maintained at a minimum pool elevation to allow for cooling the power plants.

Figure 2 shows that only eight percent (8%) of all water use in the United States is residential, yet this is where many of the federal laws dealing with water conservation have been focused. We need to focus more on conserving water in the commercial agricultural and industrial segments discussed above; there is a huge potential for water savings in these industries.

Global warming — Global warming has been attributed to increases in greenhouse gases from a variety of sources including burning of fossil fuels from industrial applications such as coal-fired electric power plants and other industrial processes in industrialized parts of the world. The greenhouse gases are contributing to an increase in global temperatures, which are melting the polar ice caps. Some experts say that the hot and arid parts of the world will expand as global warming increases.
Population increases — Increases in population place an increased demand on freshwater resources as each person needs water for: drinking; bathing; growing the crops they consume; processing the goods they consume; and making power that they use. We need to seriously consider limiting development in arid regions of the world or, simply raise water rates to discourage development and to help pay for the more expensive infrastructure costs to support the developments in arid regions.

Water utility infrastructure — Water utilities have not kept up with the increase in population growth for construction of new reservoirs and water storage facilities. I served on the water and sewer board for my township for several years and the water and sewer boards often have their hands tied when it comes to setting water utility rates. The process of raising rates is very political and takes a lot of work to justify the slightest increase in rates because most water and sewer boards are supposed to be non-profit entities. Long-range plans are needed to identify infrastructure needs and costs. Research needs to be done to look for the ideal reservoir locations and pay for the development of the reservoirs and associated water treatment facility and water distribution piping infrastructure.

Underpriced water — The price of water charged by most water utility systems does not reflect the actual value of the water — the price that water utility purveyors typically charge reflects only the costs of collection, treatment and distribution of the water. But water also provides society with many environmental benefits and those economic costs are hidden. We have the technical ability to solve the problem, we just need to do some research and adjust the water utility rates to provide money for long-term infrastructure improvements, and educate the politicians and developers to limit development in arid regions. This can be done with pricing structures of the water utility rates. Water rates could be significantly increased in dry or arid regions to support infrastructure improvements and deter development. And water rates could be kept low in areas with surplus water supplies.

It would require a significant investment in water reservoir and utility system upgrades for many areas to increase their capacity by harvesting the rainfall, and most current water pricing structures do not support the needed construction and improvements.

Wasteful practices — There are many wasteful practices that can be attributed to water being very cheap. Since water is so cheap, there is not much of an incentive for people to conserve water. The biggest users of water are agricultural, commercial and industrial users. They account for about 87 percent of all freshwater use. Water is often used in inefficient ways in agricultural, commercial and industrial uses, but with water rates so cheap there is no financial incentive to develop more efficient water uses. In residential applications, we have reduced water flow at each fixture to flow rates that are dangerously low levels, and, in some cases, we have gone too far. Currently there are many areas where there are drainline transport problems where solids are plugging up existing drainlines when more efficient plumbing fixtures are being installed on older plumbing systems with large drains installed at the minimum slope. I have heard many stories of the significant increases in sewer cleaning costs in recent years since the advent of the 1992 Energy Policy Act and lower flow fixtures. (If you know of an example or a story related to replacement of plumbing fixtures and an increase in drain stoppages, send an e-mail. I would appreciate hearing about it. I will forward it to the appropriate people. There is a new coalition called the Plumbing Efficiency Research Coalition (PERC) that will be addressing some of these issues. I will forward any information I receive on drain line transport problems to them.)

The ‘dry drains’ phenomenon

Recent water conservation and green building design initiatives have focused simply on reducing water flows and seem to have ignored health safety issues related to plumbing. Some voluntary programs that give points for water conservations and some states have looked to further reduce water use in plumbing systems by 20 percent. Currently, many areas are experiencing drainline transport problems with the reductions that were mandated by the federal government in the 1992 energy policy act, which required reductions from 3.5 gallons per flush to 1.6 gallons per flush and other similar reductions for various plumbing fixtures. Proposed legislation will reduce the maximum flushing volume for water closets to 1.28 gallons per flush.

In our rush to adopt water-saving legislation and technologies in residential commercial buildings, many green industry folks, building managers and owners failed to consider the consequences of significant reductions in water flows, particularly wastewater flows through building drain pipes. Faced with water shortages from over- development in arid regions, and, in some cases, the effects of climate change and the associated challenges of regional droughts governments around the world are pushing for water use reductions and focusing mostly on residential and commercial applications. They are not putting as much pressure on the biggest offenders which are the agricultural and industrial users. The unintended consequences of these residential and commercial water use reductions have been a significant rise in blocked drains and sewage overflows in buildings.

Plumbing and appliance manufacturers have begun to design and produce a wide range of water-saving appliances and fixtures, including dual-flush toilets, waterless urinals and low-flow showerheads.
There has been no comprehensive research done to verify if these new low-flow fixtures and appliances in conjunction with waterless urinals and greywater systems are creating health and safety problems from drain blockages in the name of water conservation. Continual reductions of water flows in the plumbing systems of buildings, however, have resulted in the phenomenon known as “dry drains,” where drain flows may be insufficient to effectively transport solids down the drain. I have always said, “There needs to be enough water in the river to float the boats.” If we reduce the drainage flow volume and leave the drain pipes the same size then the hydraulic depth of flow will be less. In older buildings there will likely be more problems than in newer buildings. In new buildings drain sizes can be designed smaller and the minimum slopes can be designed with greater slopes. The situation is further compounded with a trend to extract greywater from plumbing systems for reuse.

Dry drains is a relatively new phenomenon as it has only started to become a problem since the advent of global water conservation efforts and it seems to be more than just a drainline transport issue. Dry drains are a result of continual efforts to conserve water in many ways. Newer technologies such as high efficiency toilets (HETs) non-water using urinals and high efficiency urinals (HEUs), lower flow rate faucets and increasingly efficient water consuming appliances, reduce the amount of water discharged into sanitary waste systems. To compound the issue, when a greywater reuse system collects discharged water from lavatory basins, clothes washers, bathtubs and shower fixtures for reuse — for flushing water closets or sub-surface irrigation purposes — it is taking water away from the sanitary drainage system. (See Figure 3 and 4) The wastewater flow needs to be maintained at a level to keep the hydraulic depth of flow sufficient for proper water velocities and drain line transport.

Recent water use reduction efforts are creating an unhealthy environment and a non-sustainable condition for drainline transport, which is a serious health and safety issue. The arbitrary reductions in fixture flow rates without any technical justification for these reductions is placing drainline transport of solids wastes in serious jeopardy. Water use reductions seem to be out of balance with reality. The arbitrary 10 and 20 percent increment reductions in water usage seem to have no scientific basis. There has been no research into the water use reductions and the minimum amount of waste required for proper drainline transport. Research is needed to address the minimum water flow required for proper drain line transport without reverting to simple math for water savings that does not reflect the multiple flushes with poor performing fixtures and actual conditions in the drains. There are unique and dangerous hazards with arbitrarily reducing water consumption in plumbing fixtures without considering the consequences.

Studies show the reduction in drainline transport will be significant when reducing a 1.6 gallon per flush water closet 20 percent to flush with 1.28 gallons per flush in order to meet water use reduction quotas. This will reduce the drainline transport from about 36 feet average transport distance to about 23 feet on average. (See Figure 5). With lower flows, it will most likely be a challenge for larger horizontal buildings and drain blockages will become more common. In high-rise vertical buildings, it should be relatively easy to load a stack and have enough additional uses of water in the stack to provide sufficient drainline transport. In a remote restroom in a large horizontal building there will be drainline transport problems and an increase in drainline blockages. The cost of cleaning the drain lines, and cleaning up the spilled sewage from drainline blockages, and the increased health risks associated with the spread of bacteria and mold from drainline blockages, needs to be weighed against the few gallons of water that will be saved. The reality is, as drains block up on a regular basis people will be trained to flush twice or three times to ensure the waste goes down the drain. (I do not know what the final outcome will be, but I do know we need to research the issues and make sound decisions instead of arbitrarily picking percentages for water reductions.)

Horizontal branch connections

There has been research done overseas that addressed the fact that when drainline branches are connected horizontally they allow waste to divert or back-up into each branch as the waste flows by each branch, which lowered the hydraulic depth of flow in the main as the waste flowed past each branch. This illustrated the need to consider code requirements to roll up branches up on a 45- degree angle to prevent the waste from entering the branches and further reducing the drainline transport capacity for drains that are already at or near minimum flow rates for proper drainline transport for ultra-low flow fixtures. The research also confirmed a drain should not drop from directly overhead into a horizontal drain. Waste usually would be directed upstream from a vertical stack dropping into a horizontal drain. This allowed solids to settle in the horizontal pipe upstream of the connection and reduced the hydraulic depth of flow because of the diversion of waste. The stack should use a 45 and a Y fitting rolled to allow a rolled up 45-degree entry into the horizontal drain.

Some of these are already required in our codes and we should be more aware of using directional drainage pattern fittings as water closet flow rates are further reduced. An interesting thing of note is the fact that the minimum slope in Australia is 1.67 percent and in the U.S. the minimum slope is 1.0104 percent (1/8 inch per foot) because they generally use smaller drain pipes.

The solution is to increase the price of water

Water needs to be priced closer to its real value. Our goal should be to find ways of calculating the true economic value of water and other resources so this can be factored into social costs at the community, national, and international levels. Increasing water rates should encourage greater water conservation.
When people recognize the true economic value of water, there is an incentive to invest in products and technology that support efficient water use without mandating flows that are unrealistically low and do not allow the plumbing system to function as intended.

According to the United Nations Food and Agriculture Organization, more than eight billion people will inhabit the earth by the year 2030, requiring 60 percent more food and a significant increase in water over today’s capacities. Increased water rates will give us the funds to support the needed infrastructure improvements and provide incentives for water conservation. I also believe we should mandate research at technical data before allowing any politician to reduce water and waste flows to unrealistic levels.

Ron George is president of Ron George Design & Consulting Services. He has served as Chairman of the International Residential Plumbing & Mechanical Code Committee. To contact Ron, write to him at rgdc@rongeorgedesign.com.