Unintended Consequences

Arbitrarily lowering flow rates can result in unintended consequences causing discomfort or having a negative impact on sanitation and safety. To avoid these consequences, Plumbing Manufacturers International (PMI) members consider many factors when designing products, especially products that use less water. Among the questions they ask are:

  • Is there enough water moving through the toilet to remove waste efficiently?
  • Is there enough water flow in a showerhead or faucet to rinse shampoo from hair?
  • Is your shower valve compatible with the flow rate of your showerhead? Having this compatibility is important to avoid thermal shock—a dramatic and unexpected change in water temperature.

Just as manufacturers consider the effects of water flow on the entire plumbing system when designing products, regulators and policymakers should consider these effects before setting lower flow rates. It’s important to understand how low flow may produce unintended consequences with an adverse impact on health and safety.

PMI can be a valuable partner and resource when changes to flow rates are being considered. We can help to create an understanding of the impact flow rates may have on plumbing systems and advise on the feasibility of proposed changes. Lower flow isn’t always better.

It’s easy to forget that the number one job of plumbing is to protect public health and safety. Because of its positive impact upon sanitation and hygiene, plumbing has saved more lives than modern medicine and has dramatically increased our life expectancy.

Plumbing manufacturers have already done a tremendous amount. They spend thousands of hours engineering and testing products to achieve optimal water efficiency and performance. These products help to save water while also protecting health and safety. Manufacturers voluntarily participate in the U.S. Environmental Protection Agency’s WaterSense program, demonstrating their commitment to developing water-efficient products.

Together with PMI, these manufacturers proactively consider consumer behavior, potential unintended consequences, and health and safety concerns when developing new products. The good news: these considerations have already been addressed in existing products, and any new product bearing the WaterSense label will meet high water-efficiency and performance standards while protecting public health and safety.

Reducing flow rates may have unintended consequences, both on in-home plumbing and on “drain line carry,” which measures how far waste moves through the pipes away from the toilet after flushing. A significant concern in the design and engineering of today’s toilets, drain line carry has been the subject of extensive research within the plumbing products manufacturing industry. PMI looks to work with government agencies to ensure the highest overall system performance possible without undesirable side effects.